Chapter 3 Chemistry, Biochemistry, and Cell Physiology
1) Which of the following types of energy is strictly potential energy?
A) mechanical energy
B) radiant energy
C) chemical energy
D) electrical energy
Answer: C
Page Ref: 40
2) Once the activation energy has been transferred to a molecule,
A) it has reached the transition state.
B) it will always return to the substrate conformation.
C) it will always move on to the product conformation.
D) both A and C
Answer: A
Page
3) Ref: 42
What is the correct relationship between chemical reactions and temperature?
A) All chemical reactions are endothermic, and therefore require warmer temperatures.
B) Warmer temperatures provide the activation energy required to start chemical reactions.
C) Warmer temperatures allow more energy to be released during a chemical reaction.
D) Chemical reactions are not dependent on temperature at all.
Answer: B
Page Ref: 42
4) Which of the following bonds are classified as weak bonds?
A) hydrogen bonds, ionic bonds, van der Waals forces
B) hydrogen bonds, ionic bonds, disulfide bonds
C) ionic bonds, van der Waals forces, ester bonds
D) peptide, bonds, disulfide bonds, ether bonds
Answer: A
Page Ref: 43
5) Which of the following types of bonds is not based on attraction of one molecule for the other, but instead is based on an uncharged molecule's inability to form a bond with water?
A) van der Waals interactions
B) hydrogen bonds
C) ionic bonds
D) hydrophobic bonds
Answer: D
Page Ref: 44
6) The correct term(s) for the most abundant liquid in which other molecules are dissolved is/are
A) solvent.
B) solute.
C) solution.
D) both A and C
Answer: A
Page Ref: 45
7) Diffusion of a solute through a solution is decreased by an
A) increased concentration gradient.
B) increased size of molecule.
C) increased diffusion coefficient.
D) increased diffusion area.
Answer: B
Page Ref: 46
8) What is the osmolarity of a solution containing 3 M MgCl2 and 2 M glucose?
A) 5 OsM
B) 8 OsM
C) 11 OsM
D) 10 OsM
Answer: C
Page Ref: 47
9) Two compartments are separated by a membrane that is permeable to water and urea. Compartment I contains 1 M NaCl. Compartment II contains 2 M urea. Which of the following is a correct statement of their relationship based on the initial conditions?
A) Compartment I is isosmotic to Compartment II.
B) Compartment I is hyposmotic to Compartment II.
C) Compartment I is hypertonic to Compartment II.
D) both A and C
Answer: D
Page Ref: 48
10) pH is a measure of
A) [H+].
B) [OH-].
C) ratio of [H+] to [OH-].
D) ratio of [OH-] to [H+].
Answer: A
Page Ref: 49
11) Which of the following statements is true for a strong base?
A) It has a low pK.
B) It has a high pK
C) It easily donates [H+].
D) It dissociates slowly.
Answer: B
Page Ref: 49
12) Some of the most common buffers in animal cells are effective because
A) they have a pK value that is close to the normal pH of the cell.
B) they can bind with H+ in a chemical reaction, forming a new product that can be eliminated from the body.
C) they have very low pK values.
D) both A and B
Answer: D
Page Ref: 51
13) Metabolic pathways that include synthetic reactions are called
A) anabolic
B) catabolic
C) amphibolic
D) both A and C
Answer: D Page Ref: 51
14) Free energy (ΔG) represents the amount of energy
A) available for use from a reaction.
B) required to start the reaction.
C) that could potentially be released from a reaction.
D) that goes to randomness.
Answer: A
Page Ref:52
15) Km in the Michaelis-Menten equation represents
A) the maximum amount of substrate that can be catalyzed by the enzyme.
B) the amount of substrate required for the initial velocity to be half of the maximal velocity.
C) the amount of substrate required to start an enzymatic reaction.
D) a set constant used for all enzymatic reactions.
Answer: B Page Ref: 54
16) How can environmental conditions such as salt concentration, temperature, and pH physically affect the enzyme itself?
A) Ions can bind to the active sites of enzymes, preventing the binding of substrate.
B) Changes in temperature change the rate at which molecules interact with the enzyme.
C) All these factors can disrupt the weak bonds that hold the enzyme in its active conformation.
D) These factors affect only the substrate.
Answer: C
Page Ref: 56
17) Which of the following types of regulation involves binding to the active site?
A) competitive inhibition
B) allosteric regulation
C) covalent modification
D) both B and C
Answer: A
Page Ref: 56
18) Why is ATP an important molecule?
A) It links major pathways that release energy with those that require energy.
B) It is an energy source that is found in high concentrations in cells.
C) It is an energy source that is always available in large quantities.
D) all of the above
Answer: A
Page Ref: 58
19) The __________ structure of proteins involves interactions of amino acids that are found on different subunits.
A) primary
B) secondary
C) tertiary
D) quaternary
Answer: D
Page Ref: 59-60
20) Which of the following carbohydrates is a monosaccharide?
A) sucrose
B) lactose
C) glucose
D) maltose
Answer: C
Page Ref: 60-61
21) Which of the following pairs is correctly matched?
A) monosaccharides / glucose, fructose, sucrose
B) disaccharides / lactose, maltose, galactose
C) polysaccharides / glycogen, starch, chitin
D) glycosylation / addition of lipids to macromolecules
Answer: C Page Ref: 60-61
22) Which of the following polysaccharides performs a structural role?
A) amylose
B) glycogen
C) chitin
D) amylopectin
Answer: C Page Ref: 62
23) __________ is the metabolic pathway that synthesizes glycogen.
A) Gluconeogenesis
B) Glycogenesis
C) Glycogenolysis
D) Glycolysis
Answer: B Page Ref: 62
24) Glycolysis is an important metabolic pathway for the production of ATP because
A) it can proceed with or without oxygen.
B) it can produce ATP quickly.
C) it can be used to metabolize fats and carbohydrates equally well.
D) both A and B
Answer: D Page Ref: 63
25) All of the following are lipids, EXCEPT
A) steroids.
B) glycogen.
C) triglycerides.
D) phospholipids.
Answer: B Page Ref: 66
26) Which of the following statements correctly describes fatty acids?
A) Volatile fatty acids are the longest fatty acids
B) Saturated fatty acids are linear in structure and have one or no double bonds.
C) Medium-chain fatty acids are produced by ruminants when cellulose is fermented.
D) Double bonds in fatty acids create bends/kinks in the chain, thus altering membrane structure.
Answer: D Page Ref: 66
27) Glycerol molecules connected to three fatty acids are termed
A) monoacylglycerides.
B) diacylglycerides.
C) triglycerides.
D) cholesterol.
Answer: C Page Ref: 68
28) Cells within the adipose tissue that store lipids are called
A) adipocytes.
B) fat bodies.
C) hepatopancreas.
D) blubber.
Answer: A Page Ref: 69
29) Lipids used as a major component of biological membranes include
A) phospholipases.
B) sphingolipids.
C) free fatty acids.
D) both A and B
Answer: B Page Ref: 70
30) __________ enters the TCA cycle and forms NADH and FADH2, which can then be used for ATP production.
A) Acetyl CoA
B) Glucose
C) Pyruvate
D) A fatty acid chain
Answer: A Page Ref: 71
31) Cells can regulate the rate of the TCA cycle using all the following ways, EXCEPT
A) controlling the concentration of the substrate.
B) controlling the concentration of the required enzyme.
C) controlling the amount of energy the cell must expend for survival.
D) controlling the catalytic activity of the required enzymes.
Answer: C Page Ref: 71-72
32) Electrons can enter the electron transport system via many paths. The first point of commonality in the ETS for all these paths is
A) complex I.
B) complex II.
C) cytochrome c.
D) ubiquinone.
Answer: D
Page Ref: 72
33) Production of ATP by the mitochondrial ATP synthase is increased by
A) high levels of ATP.
B) high levels of ADP.
C) low levels of physical activity.
D) low proton motive force.
Answer: B
Page Ref: 73
34) Which of the following is a benefit of using phosphocreatine to store energy (as compared to ATP)?
A) Phosphocreatine can be used by almost any process requiring an input of energy.
B) Phosphocreatine can diffuse more easily to areas needing energy.
C) Phosphocreatine allows muscles to stop using ATP, conserving it for other uses.
D) Phosphocreatine is produced during periods of high muscle activity.
Answer: B
Page Ref:74
35) What is the advantage of storing energy as glycogen rather than as lipids?
A) It contains more energy per unit mass.
B) It does not prevent physical functions of a cell.
C) It can be mobilized very rapidly.
D) both A and B
Answer: C
Page Ref: 75
36) High concentrations of __________ indicate that a cell has plenty of energy.
A) ADP
B) AMP
C) NAD+
D) Acetyl CoA
Answer: D Page Ref: 76
37) When an ion crosses the membrane and binds to a protein to accomplish this feat, it is using
A) passive diffusion.
B) facilitated diffusion.
C) active transport.
D) either B or C
Answer: D
Page Ref: 78-79
38) Ion channels that open or close based on changes in the membrane potential are called
A) voltage-gated channels.
B) ligand-gated channels.
C) mechanogated channels.
D) porins.
Answer: A Page Ref: 79
39) Which of the following statements is true concerning secondary active transporters?
A) A symporter can bind only one particle.
B) An exchanger/antiporter will always be electroneutral.
C) Electrogenic carriers generate a charge difference across the membrane.
D) The direction in which charged particles are transported across the membrane does not affect the electrical gradient.
Answer: C Page Ref: 81
40) The main reason the interior of the cell is negative at rest is because
A) the membrane is more permeable to Na+ than any other ion.
B) the membrane is more permeable to K+ than any other ion.
C) the Na+/K+ pump is electrogenic.
D) it contains a much higher concentration of Cl-
Answer: B Page Ref: 82
41) The cytoskeleton is composed of a variety of fibers, including
A) macrotubules.
B) large filaments.
C) microfilaments.
D) all of the above
Answer: C Page Ref: 85
42) Vesicles that are produced by the ER-Golgi network may be released from the cell using the process of
A) exocytosis.
B) endocytosis.
C) phagocytosis.
D) both B and C
Answer: A Page Ref: 85
43) The extracellular matrix performs a variety of functions, including mediation of interactions between cells. __________ is a glycosaminoglycan (GAG), which provides protection and acts as a shock absorber.
A) Collagen
B) Chondroitin sulfate
C) Hyaluronan
D) Fibronectin
Answer: C Page Ref: 87
44) __________ are the sections of DNA used to encode RNA.
A) Chromosomes
B) Exons
C) Introns
D) Genomes
Answer: B
Page Ref: 91
45) Which of the following statements correctly describes the relationship between DNA, RNA, and transcription factors?
A) There is only one transcription factor for each region of DNA encoding RNA.
B) Transcription factors must always bind close to the transcription start site.
C) Phosphorylation is one way of regulating interactions between proteins required for transcription of DNA.
D) Transcription factors carry out the process of transcription themselves.
Answer: C
Page Ref: 92
46) Proteins may be degraded by proteosomes because
A) they have become damaged.
B) they are labeled with ubiquitin.
C) they are proteins which are rapidly degraded as part of the cell's control of protein levels.
D) all of the above
Answer: D
Page Ref: 93
47) Variations in proteins can arise from a SINGLE gene using
A) alternative splicing.
B) different alleles.
C) duplication of genetic material during crossover.
D) mobile elements or jumping genes.
Answer: A
Page Ref: 93
48) The second law of __________ says that the universe is moving from a state of order to one of disorder.
Answer: thermodynamics
Page Ref: 39
49) The energy of movement is termed __________ energy.
Answer: kinetic
Page Ref: 39
50) Transmembrane gradients are often referred to as____________________ gradients.
Answer: electrochemical
Page Ref: 41
51) The term that describes a macromolecule that has unfolded as a result of an increase in temperature is _________.
Answer: denatured Page Ref: 60
52) The __________ is formed by water molecules that surround water-soluble molecules in a solution.
Answer: hydration shell Page Ref: 46
53) Molecules that can be positive or negative, depending on the pH of the solution, are called __________.
Answer: zwitterions Page Ref: 50
54) All metabolic pathways in a cell, tissue, or organism can be referred to as the __________.
Answer: metabolism Page Ref: 51
55) Reversible enzymatic reactions eventually reach the point of __________, where the reactions in the forward and reverse directions are occurring at the same rate.
Answer: equilibrium Page Ref: 54
56) Energy is stored temporarily in reducing equivalents such as __________, and then released later in oxidation reactions.
Answer: NAD or NADP Page Ref: 57
57) In order to ensure that some proteins are properly folded, the cells use __________, such as heat shock proteins.
Answer: molecular chaperones
Page Ref: 60
58) The products of glycolysis are ATP, NADH, and __________.
Answer: pyruvate Page Ref: 63
59) Fatty acids with no double bonds are termed __________, and have a linear structure. Answer: saturated Page Ref: 66
60) __________ is the process of forming acetoacetyl CoA from two acetyl CoA molecules. Answer: Ketogenesis Page Ref: 68
61) Steroid hormones use __________ as a precursor molecule. Answer: cholesterol Page Ref: 70
62) The ratio between oxygen consumption and carbon dioxide production is termed the __________.
Answer: respiratory quotient
Page Ref: 75
63) The __________ describes how phospholipids, proteins, and other biological molecules come together to form a flexible cell membrane.
Answer: fluid mosaic model
Page Ref: 78
64) An __________ protein is one that spans the entire membrane or is fixed in it.
Answer: integral membrane
Page Ref: 78
65) When the potential of a cell membrane becomes less negative, or gains more positive charges, the term __________ is applied.
Answer: depolarized
Page Ref: 84
66) Winding DNA around __________ serves two major purposes: protection and compression.
Answer: histones
Page Ref: 91
67) RNA is degraded by enzymes called __________.
Answer: RNases
Page Ref: 92
68) Your book refers to the process of diffusion and mentions that both chemical and electrical gradients may influence this process. Explain why Na+ would be influenced by both chemical and electrical gradients, but glucose would not.
Answer: Diffusion allows molecules to form random distributions based on parameters such as charge and chemical concentration. A charged molecule such as Na+ will move into this distribution based on electrical and chemical relationships. Because glucose is not charged, it will not be influenced by other, charged, molecules.
Page Ref: 40-41
69) A water molecule is held together by polar covalent bonds. Because the electrons are not shared equally in this arrangement, water exhibits many unique characteristics that are beneficial for life (e.g. high surface tension). Discuss several of these characteristics and explain how they are beneficial to living organisms.
Answer: High surface tension results from attractive forces between water molecules. Smaller organisms can travel across the surface of the water if they don't break these weak bonds. Water has a lower density when frozen, which means that it will float, insulating aqueous habitats. Its high boiling point/heat of vaporization means that animals can utilize it for cooling. Heat/energy from the animal is transferred to the water, which then evaporates. Water is also an excellent solvent for charged molecules such as Na+, K+, and Cl-. The concentration of these solutes can then be used by the organism to generate electrochemical gradients. They may also be used to alter the
freezing point or osmotic pressure of an organism's internal environment.
Page Ref: 45-46
70) Temperature and pH can have profound effects on the ionization states of molecules. Explain how they can cause these effects and why ionization is important physiologically.
Answer: Molecules are frequently connected to each other via weaker or less stable bonds. The ionization state of molecules frequently is dependent upon weaker bonds. Generally, lower temperatures make bonds more stable, and higher temperatures destabilize the bonds by decreasing or increasing molecular movements. pH also changes bond strength by changing the concentration of hydrogen ions available to interact with molecules. Changes in ionization of proteins can change their folding, and therefore their function. Since proteins are integral to cell performance, disrupting their functionality will also disrupt normal processes in cells, causing possible harm to the organism.
Page Ref: 50, 55
71) Proteins, carbohydrates, and lipids all perform vital functions for an organism. Discuss some of these vital functions and what could happen to an animal if one of these biological molecules were removed from their diet.
Answer: Proteins play important roles in the structure of cells, as well as function. Receptors, transporters, and enzymes are just a few of the functional roles proteins play. Carbohydrates are important structurally and as an energy source. Carbohydrates can be used as a rapidly accessible form of energy, or they can be stored for later use. Lipids are critical for membrane formation, chemical signaling, and energy sources. Without lipids, isolation of the intracellular and extracellular components would be impossible.
Page Ref: 53-58, 60-61, 66
72) What is the role of molecular chaperones?
Answer: Form and function are important concepts in physiology. Proteins can form primary, secondary, tertiary, or quaternary structures; and these structures are critically important for the proper function of the proteins. All cells contain different molecular chaperones. Under stress, such as high temperature, proteins may unfold or denature, and denatured proteins cannot carry out their specific functions. Molecular chaperones bind to denatured proteins and refold them into the predenatured structure. For example, during heat stress, molecular chaperones called heat shock proteins (Hsp) help refold denatured proteins.
Page Ref: 60
73) Release of energy from many biological molecules requires oxygen, and yet some species are able to survive in conditions having little or no oxygen (hypoxia or anoxia). What adaptations allow them to do this?
Answer: The most obvious means is to decrease the energy requirements by slowing metabolic reactions in all or part of the tissues. This extends the supply of fuel that can be utilized without oxygen. Animals can also store more of their energy as glycogen, which can be metabolized by anaerobic glycolysis. Lastly, some animals have modified glycolytic pathways that produce end products other than lactate. These end products are less toxic, or can be removed easily from the body so they do not stop glycolysis.
Page Ref: 65-66
74) We know that fatty acids are an important source of energy for tissues. List the ketone bodies and explain why fatty acids sometimes need to be converted to ketone bodies before they can be used. Briefly summarize the two main steps in ketone metabolism.
Answer: Ketone bodies, such as acetone, acetoacetate, and β-hydroxybutyrate, are an important source of fuel for tissues that cannot use fatty acids directly. For example, brains of mammals use glucose as an energy source, however, under conditions of starvation, glucose levels are diminished. With little or no glucose available, the brain needs to obtain an alternative source of energy. Since the brain cannot use fatty acids directly, the liver converts the fatty acids to ketone bodies, which are then delivered to the brain and oxidized.
Ketogenesis is the first step that synthesizes ketone bodies. In ketogenic tissues such as the liver, Acetyl CoA is converted into the ketone bodies, acetoacetate, and βhydroxybutyrate. These ketone bodies travel via the blood and are taken up by the brain (ketolytic tissue) where through the process of ketolysis, Acetyl CoA is resynthesized.
Page Ref: 68
75) Organisms typically release more CO2 during periods of high activity. Based on your knowledge of the TCA cycle, explain how this occurs.
Answer: If activity is increased, there is an increase in the need for ATP. In order to increase ATP production, there will be an increase in the rate of TCA cycle reactions. This leads to an increase in the amount of NADH and FADH2 produced, which will go through the electron transport system to provide energy for ATP production. Another byproduct of the TCA cycle is CO2. Thus, when the rate of the TCA cycle increases, so does the rate of CO2 production.
Page Ref: 71-72
76) There are multiple ways that particles may cross a cellular membrane. Discuss the salient features of passive diffusion, facilitated diffusion, and active transport.
Answer: Passive diffusion implies that no aid is given by a protein; therefore, only molecules that are lipid soluble can cross. Passive diffusion also does not require direct energy input, so substances can move only from areas of high to low concentration. Facilitated diffusion has the same energy parameters as simple diffusion, but utilizes a protein to enable charged molecules to cross the lipid membrane. Active transport requires that molecules or ions bind to the protein and that energy will be utilized. Because energy is consumed in this type of transport, it can be used to generate gradients (i.e., "uphill" transport).
Page Ref 78-80
77) The Na+/K+ ATPase pump plays only a minor role in directly generating the resting membrane potential. (The electrogenic contributions are minimal.) However, the cell's membrane potential would not be possible without it. Explain how this can be true.
Answer: Although the electrogenic properties of the Na+/K+ ATPase pump cannot account for the resting membrane potential, it does generate a large concentration gradient for both Na+ and K+. Because of this, when a K+ channel is open, K+ is able to move through the channel and down its gradient. The movement of the charge is a major contributor to the resting membrane potential.
Page Ref: 82
78) Proteins form enzymes, transporters, channels, and many other critically important components of cells. Thus, it is essential that cells be able to regulate the amount of each protein that is available for use. What mechanisms are available to the cell for this regulation of protein levels?
Answer: Cells may increase or decrease the rate of transcription and translation. Transcription provides a "copy" of the instructions (mRNA) on how to produce a protein, and translation is the process that assembles the primary chain of amino acids from the directions on the mRNA. Cells can also remove existing proteins by enzymatic digestion. The protein is labeled by ubiquitin and then taken to a proteosome for destruction.
Page Ref: 90-93
Chapter 4 Cell Signaling and Endocrine Regulation
1) Which of the following statements is true of any communication system?
A) Neurons are always involved.
B) The endocrine system is always involved.
C) A signal must always be sent and received.
D) Signals can be sent only in electrical form.
Answer: C
Page Ref: 98
2) Which of the following choices is not a basic feature of cellular communication?
A) The signal must be produced.
B) The signal can be produced only by a eukaryote.
C) The signal must be transported to a target cell.
D) The target cell must respond to the signal.
Answer: B
Page Ref: 99
3) It is possible for cells to communicate directly (via a connection of the cytoplasm) with each other by using
A) gap junctions.
B) paracrine signaling.
C) endocrine signaling.
D) autocrine signaling.
Answer: A
Page Ref: 99
4) Which of the following statements provides inaccurate information?
A) In paracrine communication, the target cell receives chemical messenger from signal cell via diffusion.
B) A neurotransmitter is a chemical messenger that had been converted from an electrical signal.
C) Endocrine messengers are hormones.
D) Allelochemicals are chemical messengers released into the external environment by individuals of the opposite sex but of the same species.
Answer: D
Page Ref: 100
5) When chemical signals are sent between two animals, __________ communication is being used.
A) neural
B) endocrine
C) autocrine
D) exocrine
Answer: D
Page Ref: 102
6) Gap junctions are formed by
A) groups of 8-12 connexons making a pore in one cell.
B) groups of 4-6 innexins or connexins forming a pore in one cell.
C) connexons from adjacent cells connecting with each other to form a cytoplasmic bridge.
D) both A and C
E) both B and C
Answer: E
Page Ref: 101
7) When indirect signaling is used, the target cell responds to the signal when that chemical
A) binds to an enzyme.
B) binds to a receptor.
C) binds to a gene.
D) binds to the nuclear membrane.
Answer: B
Page Ref: 102
8) Neural signaling is different from other types of long-distance signaling because
A) it involves the release of chemical signals.
B) it involves the use of receptors.
C) the signal is contained within a single cell as it travels the long distance.
D) it relies on the blood to carry the signal from one cell to the next.
Answer: C
Page Ref: 102
9) A chemical is termed a neurohormone when it is
A) released by a neuron, but travels in the blood like a hormone.
B) released by an endocrine gland, but binds to receptors on a neuron.
C) released by neurons and endocrine glands.
D) known to be involved with communication, but scientists have not concluded which system uses it.
Answer: A
Page Ref: 102
10) Exocrine secretions are used to communicate between different animals and
A) to digest foodstuffs.
B) to aid in locomotion.
C) in trapping prey.
D) all of the above
Answer: D Page Ref: 103
11) Peptide hormones (chains of 50 or fewer amino acids) are first synthesized as
A) the hormone itself.
B) prehormones.
C) prohormones.
D) preprohormones.
Answer: D Page Ref: 104
12) The portion of the transmembrane receptor that binds to hydrophilic messengers is termed the
A) receptor-binding domain.
B) transmembrane domain.
C) ligand-binding domain.
D) intracellular domain.
Answer: C
Page Ref: 105
13) The vertebrate hormones involved in water and electrolyte balance in the body are called
A) mineralocorticoids.
B) glucocorticoids.
C) ecdysteroids.
D) reproductive hormones.
Answer: A Page Ref: 106
14) __________ is a generalized carrier protein that plays a major role in vertebrate blood.
A) Globulin
B) Albumin
C) Hemoglobin
D) Cholesterol
Answer: B Page Ref: 107
15) Which of the following compounds are endocrine disruptors?
A) tributyltin, polychlorinated biphenyls, tyramine, and anabolic steroids
B) polychlorinated biphynels and tyramine
C) anabolic steroids, tributyltin, and polychlorinated biphenyls
D) anabolic steroids, polychlorinated biphenyls, and tyramine
Answer: C
Page Ref: 108
16) Why do steroids take so long to generate change when they bind to intracellular receptors?
A) The intracellular receptors have very slow kinetics.
B) The bound receptors affect gene transcription rates.
C) The steroid receptor complex activates signal transduction pathways.
D) The steroid receptor complex must then exit the cell to exert its effects.
Answer: B
Page Ref: 109
17) The biogenic amine, __________, is important for invertebrates as a neurotransmitter.
A) epinephrine
B) norepinephrine
C) thyroid hormone
D) octopamine
Answer: D
Page Ref: 109
18) In the thyroid hormones, T3 and T4, the 3 and 4 refer to the
A) relative half-life (3 or 4 hours).
B) number of tyrosine molecules linked together.
C) number of iodines which are found on the hormone.
D) number of enzymes required to synthesize the hormone.
Answer: C
Page Ref: 110
19) Eicosanoids are NOT effective as hormones because
A) they are hydrophobic and cannot dissolve easily in the blood.
B) they have a very short half-life and would degrade before reaching the target cell.
C) the signaling cell cannot regulate when they diffuse through the membrane.
D) all of the above
Answer: B
Page Ref: 111
20) Antagonists are compounds that
A) prevent synthesis of new receptors.
B) prevent synthesis of hormones.
C) bind to a receptor, activating it.
D) bind to a receptor, but do not activate it.
Answer: D
Page Ref: 113
21) The response of a cell to a particular chemical messenger is determined by the
A) ligand-binding domain.
B) transmembrane domain.
C) functional domains.
D) chemical messenger itself.
Answer: C Page Ref: 113
22) Up-regulation of receptors
A) results in increased sensitivity to its ligand.
B) results in decreased sensitivity to its ligand.
C) occurs when a ligand has been present at high levels.
D) both B and C
Answer: A Page Ref: 114-115
23) A receptor that binds to a ligand at very low concentrations has a A) high dissociation constant.
B) low Ka
C) high affinity for the ligand.
D) low affinity for the ligand.
Answer: C Page Ref: 115
24) The signal transduction cascade acts as the __________ of a transducer.
A) receiver
B) transducer
C) amplifier
D) responder
Answer: C Page Ref: 118-119
25) Which of the following statements is correct?
A) Ligand-gated ion channels change the ion permeability of the membrane, which results in a response by the target cell
B) Intracellular receptors interact with hydrophilic chemical messengers
C) Receptor enzymes activate extracellular enzymes
D) G protein–coupled receptors interact with hydrophobic chemical messengers
Answer: A Page Ref: 119
26) Which domain of intracellular receptors binds to responsive elements in the nucleus?
A) DNA-binding domain
B) transactivation domain
C) ligand-binding domain
D) membrane-binding domain
Answer: A Page Ref: 119-120
27) Once a ligand binds to a receptor-enzyme,
A) the catalytic domain interacts with extracellular components.
B) the catalytic domain interacts with intracellular components.
C) the ligand-binding domain is phosphorylated.
D) the ligand-binding domain is dephosphorylated.
Answer: B Page Ref: 121-122
28) What is the correct relationship between receptor tyrosine kinases and Ras proteins?
A) Phosphorylated Ras proteins activate the tyrosine kinase.
B) Phosphorylated Ras proteins pair with a tyrosine kinase to activate other proteins.
C) Tyrosine kinase dimers phosphorylate the Ras proteins directly.
D) Tyrosine kinase dimers use GAPs and GNRPs to regulate Ras proteins.
Answer: D Page Ref: 123
29) The G-protein-coupled receptors are a diverse family with this common feature.
A) They are activated when a kinase molecule phosphorylates them.
B) They are activated when GTP is released from the G protein.
C) They are activated when GTP binds to the G protein.
D) They are activated when the α subunit binds to the β and γ subunits.
Answer: C Page Ref: 124
30) Which of the following is NOT a second messenger utilized by G proteins?
A) Ca2+
B) Na+
C) cyclic GMP
D) phosphatidyl inositol
Answer: B Page Ref: 126-127
31) Phospholipase C cuts membrane phospholipids into
A) PIP2 and DAG.
B) PIP2 and IP3.
C) Ca2+ and DAG.
D) DAG and IP3.
Answer: D Page Ref: 127
32) Which of the following is different between stimulatory and inhibitory G proteins in the cyclic AMP pathway?
A) α subunit
B) β subunit
C) γ subunit
D) all of the above
Answer: A Page Ref: 129
33) In a feedback loop, the portion that brings the variable back to its normal value is the
A) effector.
B) set point.
C) integrating center.
D) sensor.
Answer: A Page Ref: 133
34) In a __________ feedback loop, both the endocrine and nervous systems can be involved.
A) first order
B) second order
C) third order
D) both B and C
Answer: D Page Ref: 134-135
35) The organ that is connected to the hypothalamus by neurons is the A) anterior pituitary.
B) posterior pituitary.
C) adenohypophysis.
D) thyroid.
Answer: B Page Ref: 135-136
36) The posterior pituitary is
A) one of the most important endocrine organs.
B) an organ producing (not just secreting) neurohormones.
C) just a physical extension of the hypothalamus.
D) a very small thin sheet in adult mammals.
Answer: C Page Ref: 135-136
37) The hypothalamic-pituitary portal system transports blood and neurohormones between the
A) hypothalamus and the heart.
B) hypothalamus and the pituitary gland (after returning to the heart).
C) hypothalamus and the posterior pituitary.
D) hypothalamus and the anterior pituitary.
Answer: D Page Ref135-136
38) Tropic or trophic hormones
A) are found in tropical organisms.
B) have the ability to cause other hormones to be released.
C) are secreted only from the hypothalamus.
D) both B and C
Answer: B Page Ref: 136
39) Insulin is produced by
A) Islets of Langerhans in the pancreas.
B) walls of the intestines.
C) acinar cells of the pancreas.
D) red blood cells to help maintain glucose levels.
Answer: A
Page Ref: 138
40) Insulin release is NOT stimulated by
A) CCK.
B) stretch of the gut.
C) low blood glucose levels.
D) high blood glucose levels.
Answer: C
Page Ref: 138
41) When two or more hormones are __________, then the response of all the hormones when applied at the same time is greater than the sum of the responses to each hormone applied individually.
A) antagonistic
B) additive
C) synergistic
D) agonistic
Answer: C Page Ref: 139
42) Epinephrine and norepinephrine are secreted by the
A) adrenal cortex.
B) chromaffin cells.
C) heart.
D) kidneys.
Answer: B
Page Ref: 143
43) What endocrine gland secretes ACTH?
A) anterior pituitary
B) posterior pituitary
C) hypothalamus
D) adrenal medulla
Answer: A
Page Ref: 143
44) __________ are a group of steroid hormones found in all vertebrates.
A) Estrogens
B) Androgens
C) Glucocorticoids
D) All of the above
Answer: D Page Ref: 145
45) The communication and interspecies relationship between the Hawaiian bobtail squid, Euprymna scolopes, and the bacteria, Vibrio fischeri, is one of _____________. Answer: mutualism Page Ref: 98-99
46) A signaling cell's message may affect itself as well, in a process known as __________ signaling. Answer: autocrine Page Ref: 99
47) Chemical messengers used by the endocrine system are referred to as __________. Answer: hormones Page Ref100
48) In the nervous system, chemical messages cross a __________, a short distance between the signal and target cells. Answer: synapse Page Ref: 102
49) The three main classes of chemicals that act as hormones are __________, amines, and steroids. Answer: peptides Page Ref104
50) The term __________ is used for chains more than fifty amino acids long, while the term peptide is reserved for shorter chains. Answer: protein Page Ref: 104
51) The term__________ refers to any molecule that binds specifically to a protein. Answer: ligand Page Ref: 105
52) __________ is a biogenic amine used in immune responses and allergic reactions. Answer: Histamine Page Ref: 110
53) Nitric oxide is one of three gaseous chemical messengers and is produced by the enzyme __________.
Answer: nitric oxide synthase (NOS) Page Ref: 111
54) When all available receptors have ligand bound to them, we say the receptors are __________.
Answer: saturated Page Ref: 114
55) A signal of one type may be changed to another type of signal using a __________. Answer: transducer Page Ref: 118
56) When ligand-gated __________ open, ions move in or out of the cell, affecting the membrane potential.
Answer: ion channels
Page Ref: 121
57) A G protein with no known ligand or function is termed an __________.
Answer: orphan receptor
Page Ref: 126
58) The protein __________ binds four calcium molecules and then interacts with other proteins in the cell, including CaM kinases.
Answer: calmodulin
Page Ref: 126
59) __________ is the major hormone secreted by the pineal gland and is involved with circadian and seasonal cycles.
Answer: Melatonin
Page Ref: 131 (Table 4.4)
60) __________ is a hormone that is frequently involved with reproductive processes that is also part of a positive feedback loop.
Answer: Oxytocin (or Estradiol)
Page Ref: 133
61) In a __________ feedback loop, the endocrine cell acts as the sensor and integrating center.
Answer: direct
Page Ref: 134
62) Insulin and __________ are two hormones, produced by the pancreas, with antagonistic control of plasma glucose levels.
Answer: glucagon
Page Ref: 138
63) There are multiple ways in which two cells in an organism can communicate with each other: gap junctions, paracrine and autocrine signals, endocrine signals, and neural signals. Discuss the advantages and drawbacks for each of these types of signals.
Answer: Gap junctions allow direct communication, which is very fast, and allows hydrophilic signals to pass through the aqueous channel. They can be used only with cells that are adjacent to each other. Paracrine and autocrine signals are rapid, but can be used only over short distances because they rely on diffusion. Neural communication is very rapid over long distances, but the signals will not remain effective for a long period of time. Endocrine signals travel more slowly because they rely on a circulatory system for transport, but they remain active for a longer period of time.
Page Ref: 99-103
64) The chemical properties of messengers affect how they are able to communicate with the target cell. Hydrophobic and hydrophilic messengers have many differences in the way they function. Discuss these differences and how they relate to the hydrophobicity/philicity.
Answer: Hydrophobic messengers dissolve easily in lipids. Therefore, the membranes are not
barriers to them. As a result, they are able to diffuse into a cell and use intracellular receptors, and must be made on demand because they cannot be stored in vesicles. They may also use transmembrane receptors, resulting in more rapid effects. In addition, they must be transported by protein carriers over longer distances because they cannot be dissolved in the blood at high concentrations. Hydrophilic messengers, on the other hand, dissolve easily in the blood and cytosol, but cannot pass through cell membranes. Therefore, they must use transmembrane receptors and can be made ahead and stored in vesicles. They are then exocytosed when it is time for release. Because they bind to transmembrane receptors, their effects are rapid, but many are short-lived.
Page Ref: 103-104
65) If steroid hormones must be bound to protein carriers to travel through the blood, how are they able to bind to intracellular receptors? (The protein carriers cannot diffuse through the membrane.)
Answer: Steroid hormones are bound reversibly to their protein carriers, and they are soluble in low concentrations in the blood. When the steroid hormones are produced, there is such a high concentration released that they bind to the protein carriers. For the typical steroid hormone, the majority binds to the protein carrier, but a small amount remains unbound. When the blood passes by the target cell, the free steroid hormone diffuses into the cell to bind to the receptor. This creates an area of decreased concentration of the hormone, so a small amount releases from the carrier protein and is dissolved.
Page Ref: 107, 109
66) What are endocrine disruptors and how do they affect wildlife populations? Provide two examples to support your answer.
Answer: Endocrine disruptors are chemicals that interfere with the endocrine or hormone systems in animals and disrupt normal cell metabolism. Human sewage, which contains chemical pollutants, enters streams, rivers, or lakes, and can negatively affect wildlife populations. Researchers in England discovered that fish living close to the source of the sewage (outfall) had a higher percentage of intersex fish (fish that had both female and male characteristics). High levels of estrogens in the sewage feminized male fish and made them sterile. Industrial chemicals, such as tributyltin in paint (which is used to keep barnacles from attaching to painted surfaces), are also endocrine disruptors. Tributyltin has been shown to cause a condition called imposex in species of mollusks. Imposex female snails develop a penis that blocks the opening of the oviduct. If most of the eggs cannot pass out via the oviduct, reproduction is hampered, and if there is total blockage, the snail dies. In both examples, the endocrine disruptors interfere with fertility and disrupt reproduction of the species.
Page Ref: 108
67) Hormones are chemicals that are released into the blood and travel all over the body where they can have effects on their target cells. Discuss the mechanisms that allow only the target cells to respond and how target cells may have very different responses to the same hormone.
Answer: In order for a target cell to respond to a hormone, it must have a receptor. The receptor will have a ligand-binding domain that is specific for certain ligands. (Not all ligands can bind to all receptors.) Thus, only certain hormones will be able to affect a cell. Each receptor also has a functional domain that interacts with the intracellular
compartments. Two receptors could have the same ligand-binding domain, which allows them to bind to the same hormone, but have different functional domains. Thus, when the ligand binds the receptor, it will generate the effect associated with its functional domain.
Page Ref: 112-114
68) Once a ligand has bound to a receptor, it will continue to generate its response. In order to stop that response, the ligand must be removed or inactivated in some way. Describe the different ways this may be accomplished, along with features of each method.
Answer: One way in which ligands will leave their receptor is if the surrounding concentration decreases. This can be achieved by having the ligand leave via the blood where it can be degraded by the liver or kidneys, or by having adjacent cells take up excess ligand. If using the blood, this process will take a little longer. Using adjacent cells is certainly more rapid, but these cells may not always be located in close enough proximity. A third method for reducing local concentrations uses enzymes to digest any free ligand. Again, this is more rapid, but does require the enzymes to be present. Alternatively, the whole receptor-ligand complex can be endocytosed and digested within the cell. It is also possible to inactivate the functional domains of the receptor so that the effects of the ligand are no longer occurring intracellularly.
Page Ref: 115-118
69) There is a tremendous variety of signal transduction pathways with a wide range of functions. However, all these pathways have some things in common. Discuss some of these common features. Answer: All signal transduction pathways start with a ligand, the chemical message, binding to a receptor. The receptor will change its conformation because the weak bonds that hold the protein in one conformation change when the ligand binds. This leads to the activation of an intracellular substance, which may activate another substance. This cascade of events allows a very small original signal to amplify the signal in its target cell.
Page Ref: 118-119
70) Define hormones and briefly summarize their function. Provide an example to support your answer.
Answer: Hormones are chemical substances or signaling molecules of the endocrine system that regulate the activity of cells. Hormones regulate many physiological processes, such as reproduction, development, growth, metabolism, and behavior. Endocrine tissues produce hormones. Before a substance can be classified as a hormone, it must accomplish four functions: 1) have a signaling function, 2) be transported via the circulatory system, 3) bind to a specific receptor, and 4) exert its effect at low concentrations. One hormone may influence several physiological responses. For example, somatostatin hormones regulate blood glucose and other nutrients, and also affect growth and metabolism. Interaction between hormones plays an important role in physiological regulation. In glucose metabolism, we see that insulin and glucagon both regulate blood glucose levels. Hormone levels in the blood are tightly regulated and the regulation is accomplished via feedback loops.
Page Ref: 130-133
71) Compare and contrast positive and negative feedback loops.
Answer: All feedback loops have some similar parts. A sensor or receptor senses the environment. This information is relayed to an integrating center, which compares the sensed
information to the set point. The response of the integrating center will be sent to an
effector, which will carry out the response of the system. This is where the similarities end. In a negative feedback loop, the effector works to bring variables back into the set point range. In a positive feedback loop, any changes will be amplified because the effector will work to ensure that the variables will continue to move away from the set point.
Page Ref: 133-135
72))Under stressful or dangerous situations, organisms enter into the "flight-or-fight" response. This response has both neural and endocrine components. Discuss the functions of each component and how they interact with each other.
Answer: The sympathetic division of the nervous system becomes very active in response to stressful or startling stimuli. While the animal's motor neurons are stimulating skeletal muscles to contract in running away or fighting, the sympathetic drive is increasing heart rate and breathing rate. Additionally, blood vessels going toward skeletal muscles will dilate to ensure an adequate supply of oxygen and nutrients. At the same time, the sympathetic drive stimulates the adrenal medulla to release epinephrine into the bloodstream. This will also increase heart and respiratory rates. The nervous system also stimulates glucagon release and inhibits insulin release to maintain high plasma levels of glucose. The high plasma glucose levels will be enhanced by the release of glucocorticoids from the adrenal cortex.
Page Ref: 140-143
Chapter 5 Neuron Structure and Function
1) The squid served as an ideal model system to study neurophysiology because
A) squids are invertebrates and invertebrates have a simpler nervous system than vertebrates.
B) the large diameter of the squid’s neurons enabled researchers to make recordings from inside of a nerve cell.
C) fast electrical communication is a unique feature of squids.
D) squids are active predators and therefore have many nerves that can be easily studied.
Answer: B
Page ref: 154-155
2) Which of the following statements is true of nerves?
A) They are composed of groups of neurons.
B) Neurons are composed of groups of nerves.
C) They act as pipes in the body, transporting fluid.
D) Signals generated in nerves can travel only short distances.
Answer: A Page Ref: 155
3) Which of the following properties of action potentials is unique to animals?
A) They are a type of electrical signal.
B) They travel at very rapid speeds.
C) They may travel via intracellular connections.
D) They allow the organism's cells to communicate with each other.
Answer: B
Page Ref: 155
4) Axons are found in the __________ region of a neuron.
A) signal reception
B) signal integration
C) signal conduction
D) signal transmission
Answer: C
Page Ref: 156-157
5) The Goldman equation can be used to determine the resting membrane potential. It accounts for all the following factors EXCEPT
A) concentration of an ion outside the cell.
B) concentration of an ion inside the cell.
C) concentration of all ion channels in the membrane.
D) permeability of the membrane for the ions.
Answer: C Page Ref: 159
6) A cell will most likely hyperpolarize when __________ enters it.
A) Cl-
B) Na+
C) Ca2+
D) both B and C
Answer: A
Page Ref: 160, 164
7) If the sodium-potassium pump was inhibited by a drug, such as digitalis, what would happen to the membrane potential of the cell?
A) The membrane potential would slowly decrease.
B) There would be an instant loss of membrane potential.
C) There would be an instant decrease followed by an increase in membrane potential.
D) The leak channels would be disrupted.
Answer: A Page ref: 160
8) Which of the following conditions could allow a cell to become depolarized?
A) [X+]i > [X+]o
B) change in permeability to [X+]
C) membrane potential = equilibrium potential
D) all of the above
Answer: B
Page Ref: 160-161
9 If a cell is at rest (-70 mV) and ligand-gated Na+ channels open, there will be a net movement of Na+ into the cell until
A) there are no more Na+ in the extracellular fluid.
B) the Na+ channels close.
C) the membrane potential reaches the equilibrium potential for Na+ .
D) either B or C
Answer: D
Page Ref: 161-162
10) Which of the following statements is true of graded potentials?
A) They travel over long distances.
B) They have different amplitudes.
C) They are typically found in axons.
D) They travel without decrement.
Answer: B
Page Ref: 163
11) What is the correct relationship between graded potentials and action potentials?
A) Graded potentials are used to generate action potentials.
B) Action potentials are used to generate graded potentials.
C) Graded potentials and action potentials are two terms for the same phenomenon.
D) All graded potentials increase the likelihood of an action potential.
Answer: A
Page Ref: 164
12) When considering spatial summation of graded potentials, it is important to keep in mind
A) how far the potential may have traveled.
B) the initial amplitude of the potential.
C) the polarity of the potential.
D) all of the above
Answer: D
Page Ref: 165-166
13) Which of the following graded potentials will be most likely to generate an action potential?
A) a subthreshold potential
B) a suprathreshold potential
C) a hyperpolarizing potential
D) an inhibitory potential
Answer: B
Page Ref: 164-166
14) Movement of Na+ through its channels is primarily responsible for the __________ of an action potential.
A) depolarization phase
B) repolarization phase
C) hyperpolarization phase
D) after-hyperpolarization phase
Answer: A
Page Ref: 168-169
15) What mechanism causes the voltage-gated Na+ channels to close during an action potential?
A) The activation gate is voltage sensitive and closes close to the equilibrium potential for Na+ .
B) The activation gate is sensitive to K+ and closes when its intracellular concentrations drop.
C) The inactivation gate has a time-dependent closure.
D) The inactivation gate is voltage sensitive and closes close to the equilibrium potential for Na+ .
Answer: C Page Ref: 168
16) Which of the following statements is true about voltage-gated K+ channels?
A) They are triggered to open at voltages near the Na+ equilibrium potential.
B) They are triggered to open at voltages near the resting membrane potential.
C) They are triggered to open at voltages near the threshold potential.
D) They are triggered to open at voltages below the resting membrane potential.
Answer: C
Page Ref: 170
17) The relative concentrations of Na+ and K+ remain constant during a single action potential, despite movement of these ions across the membrane, because
A) they cross back immediately through recovery channels.
B) they are pumped back across using the Na+/K+ ATPase pump.
C) they are forced back across the membrane as the action potential moves away.
D) the refractory periods do not end until all ions have been returned to their original areas.
Answer: B Page Ref: 172
18) Action potentials are able to travel over long distances without decaying because
A) the axons are perfectly insulated, so no current is able to leak out.
B) the action potential uses completely different ions than graded potentials.
C) once the electrical signal has passed threshold, it is impossible for the signal to decay.
D) one action potential generates the next one in an adjacent area of membrane.
Answer: D
Page Ref: 172
19) Conduction of action potentials along an axon is termed saltatory conduction because the action potential
A) is dependent on the ions Na+ and K+, portions of salts.
B) appears to leap or jump from node to node.
C) is named after Johan Saltare, who first discovered it.
D) moves very rapidly down the axon.
Answer: B
Page Ref: 174
20) Which of the following statements correctly describes the nodes of Ranvier?
A) They are areas of myelin-covered axonal membrane
B) They are surrounded by lipid-rich Schwann cells
C) They are often referred to as internodes of the axons.
D) They contain a high density of voltage-gated channels
Answer: D
Page ref: 174
21) During the absolute refractory period, what is the state of the gates of the sodium channel?
A) Both activation and inactivation gates are closed.
B) Both activation and inactivation gates are open.
C) The activation gate is open and the inactivation gate is closed.
D) The activation gate is closed and the inactivation gate is open.
Answer: C
Page Ref: 175
22) In a neuromuscular junction, the muscle is the
A) presynaptic cell.
B) postsynaptic cell.
C) synaptic cell.
D) synapse.
Answer: B Page Ref: 176
23) What role does Ca2+ play in synaptic transmission?
A) Ca2+ is released into the synapse, transmitting a signal to the postsynaptic cell.
B) Ca2+ causes the release of vesicles from the readily releasable pool.
C) Ca2+ causes vesicles to move from the storage pool to docking proteins.
D) both B and C
Answer: D Page Ref: 177
24) During synaptic transmission,
A) the frequency of the action potential is directly correlated with neurotransmitter release.
B) the frequency of the action potential is inversely correlated with neurotransmitter release.
C) the intracellular concentration of Ca2+ remains stable because of intracellular buffers.
D) the concentration of Ca2+ is inversely related to the amount of neurotransmitter released.
Answer: A Page Ref: 177-178
25) The strongest postsynaptic signal would be achieved by which of the following combinations?
A) Low concentrations of neurotransmitter and postsynaptic receptors.
B) High concentrations of neurotransmitter and degrading enzymes.
C) Low concentrations of postsynaptic receptors and high concentrations of degrading enzymes.
D) High concentrations of neurotransmitter and low concentrations of degrading enzymes.
Answer: D Page Ref: 179
26) Neurons are capable of detecting and transducing incoming signals such as
A) light.
B) pressure.
C) environmental chemicals.
D) all of the above
Answer: D Page Ref: 180
27) A motor neuron is an example of a type of
A) afferent neuron.
B) efferent neuron.
C) interneuron.
D) sensory neuron.
Answer: B Page Ref: 180
28) __________ neurons have many dendrites, but only one axon.
A) Multipolar
B) Bipolar
C) Unipolar
D) Pseudo-unipolar
Answer: A
Page Ref: 180-181
29) All the choices below are examples of glial cells, but which one is NOT associated with the central nervous system?
A) microglia
B) astrocytes
C) schwann cells
D) oligodendrocytes
Answer: C
Page Ref: 182-183
30) A voltage-gated K+ channel that is also a delayed rectifier will
A) open very quickly in response to changes in membrane potential.
B) make it very difficult to start an action potential.
C) delay the start of an action potential.
D) open slowly, increasing the length of the action potential.
Answer: D
Page Ref: 184
31) Which of the following combinations of voltage-gated channel densities would most easily allow an action potential to be generated?
A) high density of K+, low density of Na+
B) low density of K+, high density of Na+
C) high density of K+ and Na+
D) low density of K+ and Na+
Answer: B
Page Ref: 184-185
32) Which of the following statements is correct concerning the variation of voltage-gated ion channels?
A) Na+ channels have much greater diversity than K+ channels.
B) Typically, a more complex nervous system also contains a greater diversity of channels.
C) There is a great diversity of channels, but within a single organism, only one isoform of a channel can exist.
D) There is a large diversity of channels, but they show no physiological significance.
Answer: B
Page Ref: 185
33) Given the information below, the neuron with the characteristics listed in choice __________ would have the fastest conduction velocity.
A) myelinated, 50 μm diameter
B) myelinated, 10 μm diameter
C) unmyelinated, 50 μm diameter
D) unmyelinated, 10 μm diameter
Answer: A Page Ref: 185
34) When looking at a small patch of axonal membrane, the __________ and __________ are arranged in parallel with each other, allowing current to flow through both of them if possible.
A) Rm; Ri
B) Ri; Cm
C) Rm; Cm
D) Cm; Re
Answer: C Page Ref: 185-188
35) A membrane's length constant will be greatest when
A) Rm is low.
B) Ri is low.
C) Rm is high.
D) both B and C
Answer: D Page Ref: 189
36) What is the benefit of using action potentials for conductance of electrical signals, rather than simply using electrotonic spread?
A) Action potentials have a greater speed.
B) Action potentials can vary in amplitude to convey more information.
C) Action potentials can travel over longer distances.
D) both A and C
Answer: C Page Ref: 189
37) A capacitor can store more change when it has a
A) large surface area and thick insulating layer.
B) small surface area and thin insulating layer.
C) large surface area and thin insulating layer.
D) small surface area and thick insulating layer.
Answer: C Page Ref: 190-191
38) Squid benefit from having axons of multiple sizes that innervate their muscle fibers in the mantle because
A) squid need larger diameter axons to innervate larger groups of fibers.
B) the larger diameter axons innervate fibers that are farther away because the signals are conducted more rapidly through them.
C) smaller fibers are not energetically efficient.
D) larger fibers generate larger action potentials, which allows for more neurotransmitter release.
Answer: B
Page Ref: 191
39) Increasing axon diameter decreases membrane and intracellular resistance, so it seems the two might cancel each other out in terms of their effect on the conduction speed. Yet, conduction speed is increased by increasing diameter size. Why?
A) Membrane resistance doesn't really affect conduction speed that much.
B) Intracellular resistance doesn't really affect conduction speed that much.
C) Membrane resistance decreases linearly while intracellular resistance decreases by the square of the radius.
D) Intracellular resistance decreases linearly while membrane resistance decreases by the square of the radius.
Answer: C
Page Ref: 191-192
40) Myelination increases the speed of conduction by decreasing the time constant and increasing the length constant. It achieves this by
A) increasing membrane resistance and decreasing capacitance.
B) increasing both membrane resistance and capacitance.
C) decreasing membrane resistance and increasing capacitance.
D) decreasing both membrane resistance and capacitance.
Answer: A
Page Ref: 193
41) Which of the following is a true difference between electrical and chemical synapses?
A) Electrical synapses are found in the central nervous system.
B) Electrical synapses are the most common type of synapse.
C) Electrical synapses typically send information in one direction (presynaptic cell to postsynaptic cell).
D) Electrical synapses are much faster.
Answer: D
Page Ref: 194
42) The synapse formed by __________ in the peripheral nervous system are similar in morphology to the __________ in the central nervous system.
A) terminal boutons; axon varicosities
B) axon varicosities; en passant synapses
C) en passant synapses; spine synapse
D) spine synapse; terminal boutons
Answer: B Page Ref: 195
43) Axodendritic synapses are composed of __________ for the presynaptic cell and __________ for the postsynaptic cell.
A) axons; axons
B) dendrites; axons
C) axons; dendrites
D) axons; cell somas
Answer: C Page Ref: 195
44) Neurotransmitters are composed of a variety of different chemicals, including
A) amino acids.
B) neuropeptides.
C) biogenic amines.
D) all of the above
Answer: D Page Ref: 196
45) Metabotropic receptors typically generate a response by
A) becoming an open channel as soon as the ligand binds.
B) activating gene transcription.
C) opening an ion channel via signaling from a second messenger cascade.
D) both B and C
Answer: D Page Ref: 198
46) Which of the following neurotransmitters is typically NOT classified as a biogenic amine?
A) acetylcholine
B) serotonin
C) epinephrine
D) dopamine
Answer: A Page Ref: 199
47) Neurons can produce and release different neurotransmitters. It is hypothesized that the type of neurotransmitter released is determined by
A) the amplitude of the action potential.
B) the frequency of the action potential.
C) the neurotransmitter that is available.
D) random chance.
Answer: B Page Ref: 201
48) __________ is a type of synaptic plasticity that results in a decrease of neurotransmitter release after repeated action potentials.
A) Synaptic facilitation
B) Post-tetanic potentiation
C) Synaptic depression
D) Presynaptic depression
Answer: C
Page Ref: 201
49) Post-tetanic potentiation at a synapse is generated by a
A) high frequency of stimulation.
B) long period of time between stimuli.
C) high frequency of stimulation followed by a short break.
D) low frequency of stimulation followed by a short break.
Answer: C
Page Ref: 201
50) The action potential of Chara, an algae species, is generated by
A) Cl- efflux via voltage-gated channels.
B) Cl- efflux via channels opened by second messenger pathways.
C) Ca2+ influx via channels opened by second messenger pathways.
D) Ca2+ efflux via voltage-gated channels.
Answer: B
Page Ref: 204
51) Hodgkin and Huxley, who first showed electrical current was generated by selective permeability of the membrane to ions, used the __________ as a model system.
Answer: giant squid axon
Page Ref: 154
52) The electrical signal produced by neurons, called an __________, is capable of traveling over long distances.
Answer: action potential
Page Ref: 156-157
53) A __________ transmits signals from the central nervous system to skeletal muscles.
Answer: motor neuron
Page Ref: 156
54) When a cell __________, the charge difference between the intracellular and extracellular fluids decreases.
Answer: depolarizes
Page Ref: 160
55) When ligand-gated receptors open channels in dendrites, the resulting electrical signal is called a __________.
Answer: graded potential
Page Ref: 163-164
56) When a graded potential arrives at the axon hillock before an earlier graded potential has died out, the two potentials can be added in a process known as __________ __________.
Answer: temporal summation
Page Ref: 165
57) The channels that generate an action potential are triggered to open by a change in membrane potential because they are __________ channels.
Answer: voltage-gated
Page Ref: 167
58) The area of the axon covered with myelin and found between the nodes of Ranvier is known as an __________.
Answer: internode
Page Ref: 174
59) Oligodendrocytes and Schwann cells wrap themselves around neuronal processes, forming __________, a substance that increases conduction rates and decreases current leak.
Answer: myelin
Page Ref: 174
60) Vesicles found in the axon terminals that contain neurotransmitter are called __________.
Answer: synaptic vesicles
Page Ref: 177
61) Neurotransmitter is packaged in vesicles that are released in response to an action potential. This leads to a "steplike" increase in the amount of neurotransmitter being released (one step for each vesicle), termed __________.
Answer: quantal release
Page Ref: 177
62) __________, or afferent neurons, are capable of sending information about the environment (internal and external) to the central nervous system.
Answer: Sensory
Page Ref: 180
63) Most neurons show __________, such that one end of the neuron receives a signal and the other sends a signal. The cnidarians are an exception to this principle.
Answer: polarity
Page Ref: 182
64) The membrane of an axon acts as a resistor and a __________ because it resists the flow of current and can store an electrical charge.
Answer: capacitor
Page Ref: 187-188
65) The distance a membrane potential can travel before reaching 37% of its original value is termed the __________.
Answer: length constant
Page Ref: 188
66) Synapses where pre- and postsynaptic cells are directly connected so that current can pass from one cell to another are called __________.
Answer: electrical synapses
Page Ref: 194
67) Neurotransmitters are synthesized in the cell body, then transported in vesicles to the axon terminals using __________.
Answer: fast axonal transport Page Ref: 197
68) Inhibitory neurotransmitters generally cause ________________, and the changes in membrane potential are referred to as inhibitory postsynaptic potential. Answer: hyperpolarization Page ref: 198
69) Muscarinic ACh receptors are an example of a __________ receptor, which eventually lead to the opening of an ion channel.
Answer: metabotropic Page Ref: 198-199
70) __________ receptors bind both epinephrine and norepinephrine. Answer: Adrenergic Page Ref: 199
71) A decrease in neurotransmitter release with repeated action potentials is termed .
Answer: synaptic depression Page Ref: 201
72) Neurons have four functional zones, and each performs a task required for communication. What are these four zones and what structural features found in each allow it to perform its function?
Answer: The four zones are those for signal reception, signal integration, signal conduction, and signal transmission. The first zone contains the dendrites, and frequently the cell body. Both structures contain receptors that are activated by a chemical, mechanical, electrical, or other signal and transduce that signal into an electrical one. The second zone, signal integration, is a common point for all signals received in the reception zone. It contains the axon hillock and forms the junction between the reception zone and conduction zone. Thus, it is an excellent point for integrating or summing signals from the dendrites and cell body. The third zone allows for signal conduction. It contains an axon and its branches, or collaterals. It is often covered with a myelin sheath to help insulate the signal and improve conduction along the axon. The last zone is used for signal transmission. In this zone, the axon terminals closely approach another cell, forming a synapse. The axon terminal has the ability to transduce the electrical signal into a chemical one by triggering the release of neurotransmitter stored in the terminals.
Page Ref: 155-157
73) When membrane potential changes, we use the terms depolarization, hyperpolarization, and repolarization. Explain what is happening to the membrane potential in relation to the extracellular fluid during depolarization and hyperpolarization and how each phase could be achieved by negatively charged ions. Next, explain how it is possible for the membrane to be in both hyperpolarization and repolarization at the same time.
Answer: The terms depolarization and hyperpolarization describe the relationship in the potential difference between the intracellular and extracellular fluid. The intracellular fluid is typically negatively charged compared to the extracellular fluid when the cell is at rest. If that potential difference becomes greater (i.e., more negative), the cell is hyperpolarizing. This can be achieved when negatively charged ions move into the cell. When the potential difference decreases, (i.e., becomes less negative), the cell is depolarizing. This occurs when negatively charged ions leave the cell. The term repolarization is used when the cell membrane potential is returning to the resting membrane potential. Thus, after a depolarization, the membrane must hyperpolarize to return to the resting membrane potential (repolarization).
Page Ref: 157-161
74) Neurons use both graded and action potentials to carry electrical signals from one point to another. Describe the similarities and differences between these two types of signals that could be seen within an individual neuron.
Answer: Both signals are electrical, which means that both rely on channels opening and ions flowing through the channels to generate the changes in membrane potential. There are some significant differences. Many of these differences are generated because of the types of ion channels that are used to create the potential. Action potentials rely on voltage-gated Na+ and K+ channels. Graded potentials are generated by ligand-gated or mechanically gated channels. As a result, graded potentials are created by a much larger range of ions flowing through them, allowing them to have different magnitudes and durations, as well as being depolarizing or hyperpolarizing. Graded potentials can also be summed at the axon hillock. Action potentials are always depolarizing (Na+ always flows in), are always the same magnitude and duration, and cannot be summed. Graded potentials will decay over distance, while action potentials are regenerated, allowing them to travel over long distances.
Page Ref: 163-172
75) Briefly state the importance of voltage-gated Na+ channels. Explain why the tetrodotoxin (TTX) found in California newts (Taricha torosa) does not kill the newts. Would you expect garter snakes (Thamnopis sirtalis), which are predators of newts, to die once they consume the toxic newts?
Answer: Voltage-gated Na+ channels are important for the depolarizing phase of an action potential and thus for transmission of electrical signals. California newts, which contain the toxin TTX (TTX blocks voltage-gated sodium channels), have a mutation in one of the voltage-gated Na+ channels that does not allow the TTX to bind, and therefore, the newt is immune to the toxin. If garter snakes consume TTX-containing newts without dying, then these garter snakes must also have mutations that make their voltage-gated Na+ channels insensitive to TTX. Garter snakes and other predators without the mutation would most likely die if they consumed the toxic newts.
Page ref: 170 (Applications 5.2)
76) The absolute and relative refractory periods of an action potential determine other parameters of action potentials such as causing unidirectional conduction and limiting their frequency. Describe what is happening during each of the refractory periods. Then use this information to describe how the different periods affect conduction and frequency.
Answer: Action potentials have both absolute and relative refractory periods. During the absolute refractory period, the inactivation gate is closed and will not be reset until the membrane has repolarized sufficiently. During the relative refractory period, many, but not all, Na+ channels have been reset. Additionally, the membrane is typically hyperpolarized below the resting membrane potential. This means it would take a stronger than normal stimulus to bring the potential to threshold and recruit enough Na+ channels to generate a new action potential. When action potentials are traveling along, the depolarization spreads in both directions (electrotonically), but can only activate channels that are not in the absolute refractory period (i.e., in front of the AP.)
Channels in the relative refractory period can be opened, but by the time the current spreads to them, it has decayed enough that it is no longer able to be the stronger than normal stimulus required to generate a new AP. Thus, the AP can move only in the forward direction. The frequency of action potentials is also limited by the absolute refractory period. It is impossible for another action potential to be started until the channels have reset from the first one; thus, there is a limit to the frequency (number of action potentials per unit time).
Page Ref: 169-175
77) You have isolated two neurons, joined by a synapse, in a Petri dish. You have stimulated the first neuron at the axon hillock and successfully generated an action potential. However, there is no response by the postsynaptic neuron. Describe possible malfunctions in synaptic transmission that would prevent the postsynaptic neuron from responding as it should. Answer: There are a number of reasons for failure of synaptic transmission. Starting with the presynaptic cell, it is possible that Ca2+ is not able to enter the axon terminal (either the channels are not opening, or there is too little Ca2+ in the extracellular fluid). If Ca2+ cannot enter, then it will not signal the readily releasable pool of neurotransmitter (NT) to be exocytosed. If the Ca2+ is able to enter, perhaps it is not interacting with the storage pool of neurotransmitter. In this case, after the initial release, there is no more NT on the docking proteins. Other problems may occur in the synapse itself. The NT may be degraded by enzymes before it has a chance to bind to receptors on the postsynaptic neuron, or it may diffuse away too quickly. Finally, the receptors on the postsynaptic membrane may be malfunctioning. If they are unable to bind to the NT, or cannot transduce the signal into an electrical one, there will be no detectable response by the postsynaptic cell.
Page Ref: 176-179
78) Glial cells were originally thought to play a very minor role in the nervous system. In fact, their name is derived from the Greek word for glue. However, recent findings have demonstrated a number of functions for these cells. Discuss these functions and their importance in allowing neurons to function.
Answer: Glial cells are known to play a number of roles in the nervous system. In the peripheral nervous system, Schwann cells form the myelin, or insulation, around the axons of motor or sensory neurons. They are also capable of helping to repair damage to these neurons. In the central nervous system, oligodendrocytes generate the myelin sheath. Astrocytes are found throughout the CNS, even wrapping around synapses. They regulate the extracellular environment and can help control levels of neurotransmitters at the synapse. Microglia also help maintain neurons by removing debris and dead cells from the CNS. Lastly, ependymal cells are found lining the ventricles of the brain, and use their cilia to move the cerebrospinal fluid through the cavities of the brain.
Page Ref: 183
79) A high speed of conduction along axons is very important for the survival of organisms, particularly when quicker response times allow escape from a predator. Many factors affect speed of conduction, including temperature, myelination, and the diameter of the axon.
Discuss how myelination and diameter affect the cable properties of a neuron and affect conduction speeds.
Answer: To understand how myelination and axon diameter affect conduction speeds, it is important to understand the basics of how current flows along an axon. Positively charged particles enter the cell via channels during an action potential. They then flow through the intracellular fluid up and down the axon. Outside the axon, positive charges are also flowing, but in the opposite direction. To complete the circuit, it is necessary for some charges to cross the membrane, flowing out of the cell. To achieve the greatest speed of conduction, it is important to have low resistance to flow inside and outside the cell, and high resistance across the membrane. This means most of the charge will flow down the axon, rather than out of it. Additionally, we have to think about capacitance. When charges flow across a membrane, they first build up on opposite sides of the membrane, then are able to flow across. If it takes a long time to store up the charge, it will take a longer time for the current to continue flowing down the axon. A large diameter axon will provide a very low internal resistance to flow. A myelinated axon will have a very high resistance to flow across the membrane, and also a very small capacitance. This allows for very high speeds of conduction. Page Ref: 185-193
80) Describe the differences between electrical and chemical synapses in terms of mechanisms and functional characteristics of transmission
Answer: Transmission across an electrical synapse is very fast because there is no synaptic delay, just an electronic current spread. In electrical synapses, flow of information occurs in either direction because ions can easily travel via the gap junctions that connect cells.
In a chemical synapse, the flow of information is in one direction, from the presynaptic cell to the postsynaptic cell. The presynaptic cell’s electrical signal is converted to a chemical signal via neurotransmitters There is also docking and fusion of synaptic vesicles and diffusion across the synapse. The receptors in the postsynaptic cell convert the chemical signal to an electrical signal All these steps result in a relatively slower transmission rate of information compared to electrical synapses. However, due to the presence of numerous
neurotransmitters, these neurotransmitters have diverse effects on the postsynaptic cells.
Page Ref: 194 (Fig. 5.32)
81) There are some neurotransmitters, such as acetylcholine, that are used extensively throughout the nervous system. Yet a single type of neurotransmitter can have multiple effects. How is this possible?
Answer: For neurotransmitters to generate their effects in other cells, they must bind to a receptor. It is possible for a neurotransmitter to bind to a variety of receptors, which are typically made up of multiple protein subunits. Each of these subunits may have several isoforms. As a result, there are many combinations of neurotransmitter/receptor bindings, each of which can generate its own unique response in the cell.
Page Ref: 198-202
Chapter 6
Cellular Movement and Muscles
1) Which of the following is a motor protein?
A) myosin
B) microtubules
C) microfilaments
D) intermediate filaments
Answer: A
Page Ref: 209
2) Which of the following types of movement may NOT require use of a motor protein?
A) muscle contraction
B) flagellar movement
C) vesicle transport
D) amoeboid movement
Answer: D
Page Ref: 209
3) Microtubules are strings of tubulin proteins that are formed from a
A) dimer of α-tubulin.
B) single string of α-tubulin.
C) dimer of one α-tubulin and one β-tubulin.
D) hexamer of α-tubulins and β-tubulins twisted together.
Answer: C
Page Ref: 212
4) Microtubule growth will stop if
A) concentration of tubulin drops below a critical point.
B) cholchicine binds to free tubulin.
C) GTP on the β-tubulin is hydrolyzed.
D) all of the above
Answer: D Page Ref: 213-214
5) The microtubule disruptor, vinblastine
A) is derived from the autumn crocus.
B) kills dividing tumor cells by disrupting the mitotic spindle.
C) kills cells that line blood vessels, thus cutting off blood flow to tumors.
D) B and C
Answer: D Page Ref: 215
6) __________ vesicles are transported to the membrane by the motor protein __________.
A) Filled; kinesin
B) Filled; dynein
C) Empty; kinesin
D) Empty; dynein
Answer: A
Page Ref: 216
7) Kinesin-associated proteins have the ability to do all of the following EXCEPT
A) affect kinetics of movement.
B) affect the type of cargo binding to kinesin.
C) affect the isoforms used to build kinesin.
D) affect the ATP hydrolysis rate.
Answer: C
Page Ref: 216
8) Dyneins generate movement in cilia and flagella by
A) the dynein moving along its own microtubule, pulling the cell membrane with it.
B) the dynein on one side of the flagella moving along its neighbor's tubule.
C) all dyneins moving along their neighbors' tubules in a synchronized fashion.
D) the dynein pushing on the neighboring tubules, generating movement.
Answer: B
Page Ref: 216
9) The microfilament __________ is commonly used with its motor protein, __________.
A) actin; dynein
B) nexin; dynein
C) actin; myosin
D) nexin; kinesin
Answer: C
Page Ref: 217
10) What is the function of capping proteins?
A) to prevent increased growth of microfilaments
B) to stabilize the microfilament, allowing for increases in length
C) to attach microfilaments together at a common point
D) to allow the microfilament to bind to the cell membrane
Answer: B
Page Ref: 217
11) Which of the following statements about movement via actin polymerization is true?
A) Movement can be generated using actin polymerization by itself (no motor proteins).
B) Movement occurs only when motor proteins move across actin polymers.
C) Actin polymerization prevents growth of filapodia.
D) During cell movement there is always a net growth of actin polymer length.
Answer: A
Page Ref: 218
12) Filapodia
A) are rodlike extensions of cells formed by myosin fibers.
B) are used by nerve cells to make physical contact with neighboring cells.
C) resemble pseudopodia found in protists.
D) arise from sheetlike networks of microfilaments.
Answer: B Page ref: 218
13) Actin and myosin work together to allow
A) movement of vesicles throughout the cell.
B) movement of muscle.
C) movement of the cell itself.
D) all of the above
Answer: D Page Ref: 218-219
14) The __________ of the myosin is where ATP is broken down, providing energy for movement.
A) tail
B) neck
C) head
D) light chains
Answer: C Page Ref: 219
15) In the cross-bridge cycle, the power stroke of myosin is immediately preceded by which of the following events?
A) the hydrolysis of ATP
B) binding the actin
C) releasing Pi
D) binding new ATP
Answer: C Page Ref: 221
16) The unitary displacement of the myosin refers to
A) how many actins are displaced by myosin.
B) how far along the actin filament the myosin can move in one cycle.
C) how many units of time pass during one cross-bridge cycle.
D) how much time the myosin stays bound to the actin before it is displaced.
Answer: B Page Ref: 222
17) When myosin moves along the actin, it goes through cycles of binding and releasing (duty cycle). How does myosin keep from losing its place on the actin when it releases?
A) The time of the duty cycle is large (.99) so that it is only unattached a short time.
B) The myosin is still attracted to the actin by weak electrostatic forces that prevent it from moving too far away during release.
C) The myosin is attached to the actin by another protein that it uses as a safety line to prevent it from slipping too far back.
D) The myosin is arranged in dimers so that when one releases, the other is bound.
Answer: D Page Ref: 222
18) The main component in __________ of a muscle cell is polymerized actin.
A) thin filaments
B) thick filaments
C) A-bands
D) Z-disks
Answer: A Page Ref: 224
19) The thin filaments are stabilized by being capped by __________ at one end and CapZ at the other.
A) troponin
B) tropomodulin
C) tropomyosin
D) a polymer of all three
Answer: B Page Ref226
20) The sarcomere, or contractile unit of striated muscle, extends from one __________ to the next.
A) Z-disk
B) M-line
C) A-band
D) I-band
Answer: A Page Ref: 226
21) In what ways is muscle myosin II the same as the myosin used in vesicle travel?
A) They have the same unitary displacement.
B) They have the same length of duty cycle.
C) Myosin attaches to actin.
D) There is a chance myosin can drift away from actin.
Answer: C Page Ref: 226
22) A single skeletal muscle cell is referred to as a
A) cardiomyocyte.
B) sarcomyocyte.
C) myofibril.
D) myofiber.
Answer: D
Page Ref: 228
23) During which phase of an excitation-contraction cycle does depolarization occur?
A) excitation
B) inhibition
C) contraction
D) relaxation
Answer: A
Page Ref: 234
24) When Ca2+ is present at high levels in the sarcoplasm of striated muscles, then
A) TnI has a strong interaction with actin.
B) TnC has a strong interaction with TnI.
C) TnT has a strong interaction with myosin.
D) TnT has a weak interaction with Ca2+
Answer: B
Page Ref: 229
25) Muscle contraction kinetics can be affected by
A) affinity of troponin for Ca2+
B) pH.
C) temperature.
D) all of the above
Answer: D
Page Ref: 229-230
26) Contraction of striated muscle is regulated by
A) TnC's affinity for Ca2+ (and nothing else).
B) alternating the two available isoforms of myosin.
C) utilizing different combinations of muscle protein isoforms.
D) the rate at which Ca2+ is able to bind to actin.
Answer: C
Page Ref: 229
27) Which myosin isoform is found in fast-twitch muscle?
A) perinatal
B) extraoccular
C) type I
D) type IIb
Answer: D
Page Ref: 229-230
28) Skeletal muscle may be used in a __________ contraction.
A) shortening
B) isometric
C) lengthening
D) both A and B
E) all of the above
Answer: E
Page Ref: 230
29) What is the underlying mechanism that allows striated muscles to contract more rapidly when very little force is required?
A) The muscle is shortening so rapidly that some myosin heads are moved to their new position without actually generating any force.
B) Fewer myosin heads actually attach to the actin, increasing the rate of shortening.
C) Lighter loads stimulate only a very high speed, low tension isoform of myosin.
D) Lighter loads stimulate a myosin isoform with a very long unitary displacement.
Answer: A
Page Ref: 232-234 (Box 6.2)
30) Cardiomyocytes have a much longer repolarization period than skeletal muscles due to their
A) voltage-sensitive Na+ channels.
B) voltage-sensitive Ca2+ channels.
C) voltage-sensitive K+ channels.
D) voltage-sensitive Cl- channels.
Answer: B
Page Ref: 235-236
31) Factors such as adenosine and catecholamines alter heart rate by affecting the kinetics of
A) voltage-sensitive Cl- channels.
B) voltage-sensitive Na+ channels.
C) funny channels.
D) voltage-independent K+ channels.
Answer: C
Page Ref: 238
32) Motor neurons release __________ into the neuromuscular synapse, which may generate depolarization at the motor end plate.
A) acetylcholine
B) adenosine
C) catecholamines
D) GABA
Answer: A
Page Ref: 237
33) Action potentials can be conducted into the muscle along invaginations of the sarcolemma, or __________.
A) sarcoplasmic reticulum
B) T-tubules
C) terminal cisternae
D) sarcotubes
Answer: B
Page Ref: 238
34) Most of the Ca2+ stored in the sarcoplasmic reticulum is bound to
A) parvalbumin.
B) troponin.
C) calsequestrin.
D) ryanodine.
Answer: C
35) Dihydropyridine receptors (DHPR) are also called __________ because of their large Ca2+ conductance.
A) T-type Ca2+ channels
B) N-type Ca2+ channels
C) L-type Ca2+ channels
D) Na+/ Ca2+ exchangers (NaCaX)
Answer: C
Page Ref: 240
36) Which of the following pumps is specifically used to return Ca2+ to the sarcoplasmic reticulum?
A) Ca2+ATPase
B) NaCaX
C) parvalbumin
D) SERCA
Answer: D
Page Ref: 242
37) Muscle fiber types may be termed glycolytic or oxidative in reference to
A) the amount of myoglobin.
B) the speed of contraction.
C) the metabolic processes.
D) the myosin heavy chain isoforms used.
Answer: C
Page Ref: 242
38) Smooth and striated muscle share many common features, including
A) organization of filaments into sarcomeres.
B) use of actin and myosin in contraction.
C) a ratio of 2:1 thin to thick filaments.
D) dependence on T-tubules for spread of depolarization.
Answer: B
Page Ref: 245
39) Muscle fiber types can be changed in response to
A) activity levels.
B) temperature.
C) thyroid hormone levels.
D) all of the above
Answer: D
Page Ref: 244-245 (Box 6.3)
40) Invertebrate muscle, like vertebrate muscle,
A) has two major forms of muscle (striated and smooth).
B) utilizes thick and thin filaments in contraction.
C) makes use of obliquely striated muscle.
D) both A and C
Answer: B
Page Ref: 248
41) Vertebrate striated muscles composed of twitch fibers are able to produce a graded contraction by
A) recruiting different numbers of motor units.
B) summing EPSPs in the motor end-plate region.
C) having excitatory and inhibitory input to a single muscle.
D) Vertebrate muscles are unable to produce graded contractions.
Answer: A
Page Ref: 249
42) Asynchronous flight muscles in insects are able to achieve contractions in the range of 2501000 Hz because
A) they have very fast Ca2+ ATPase pumps.
B) they have muscles that don't depend on Ca2+ regulation at all.
C) they have very high amounts of parvalbumin in the cytosol.
D) the TnC can rapidly change its affinity for Ca2+, leading to rapid contraction/relaxation cycles.
Answer: D
Page Ref: 250-251
43) Mollusc catch muscles are able to generate tension for long periods of time without consuming much energy. We do not understand everything about how this is accomplished, but there are unique proteins, such as __________, that seem to play a role.
A) twitchin
B) myosin
C) titin
D) all of the above
Answer: A Page Ref: 251
44) Which of the following statements is true concerning sonic muscles?
A) They contract at much higher frequencies than the locomotor muscles found in the same organism.
B) They utilize completely different muscle proteins.
C) They have a very slow rate of cross-bridge cycling.
D) They are able to contract rapidly while producing large amounts of force.
Answer: A
Page Ref: 252
45) Which of the following statements is inaccurate with respect to sonic muscles?
A) Rattlesnakes, cicadas, and toadfish are examples of animals with sonic muscles.
B) Animals can modify their muscles to operate some 10 times faster than the fastest locomotor muscles in that animal.
C) The fast speed can be attributed to some muscles being able to lengthen sarcomeres.
D) Sonic muscles must have fast Ca2+ transport.
Answer: C
Page Ref: 252
46) How does the heater organ of a swordfish produce heat?
A) The muscle contracts very rapidly, producing large quantities of heat.
B) The myosin binds very weakly to the actin, utilizing large amounts of ATP that ultimately produces heat, but no tension.
C) The sarcoplasmic reticulum releases and recovers large amounts of Ca2+, releasing heat as a by-product of these processes.
D) The muscle fibers are rapidly generated and degraded, which produces large quantities of heat as a by-product.
Answer: C
Page Ref: 253
47) Animals are capable of movement because they have a unique type of cell, the __________.
Answer: muscle cell
Page Ref: 208-209
48) Microtubules are organized in cells with the ends near the nucleus in a region known as the __________, or MTOC for short.
Answer: microtubule-organizing center
Page Ref: 211
49) Microtubule-associated proteins that stabilize the tubules are called __________.
Answer: stable-tubule only polypeptides (STOPs)
Page Ref: 213
50) The Pacific yew tree produces the microtubule disrupter known as ___________.
Answer: taxol
Page Ref: 215
51) When microfilaments remain the same size by increasing length on one end and decreasing their length on the other, we say they are __________.
Answer: treadmilling Page Ref: 217
52) An increase in surface area of a membrane, or contact with another cell, can be achieved by generating __________, thin, rodlike extensions produced by polymerizing actin fibers.
Answer: filapodia
Page Ref: 218
53) The __________ explains how the myosin head moves down the actin polymer, generating movement.
Answer: sliding filament model
Page Ref: 219
54) The term refers to the time in each cross-bridge cycle that myosin is attached to actin.
Answer: duty cycle
Page Ref: 222
55) Specialized animal cells that have contractile properties are called __________, or muscle cells.
Answer: myocytes Page Ref: 223
56) The thick filament of striated muscle is indirectly connected to the Z-disk by the compressible protein __________.
Answer: titin
Page Ref: 226
57) An __________ contraction is one in which the length of the muscle does not change significantly.
Answer: isometric Page Ref: 230
58) The axon termini of motor neurons are found in the __________ of the sarcolemma of vertebrate skeletal muscles.
Answer: motor end plate Page Ref: 237
59) __________ muscle cells can depolarize and contract on their own, as opposed to neurogenic muscle cells which require neuronal innervation.
Answer: Myogenic Page Ref: 238
60) In skeletal muscle, the dihydropyridine and ryanodine receptors are linked to allow for __________ Ca2+ release that is independent of local Ca2+ concentrations.
Answer: depolarization-induced Page Ref: 240-241
61) In smooth muscle, bundles of filaments attach to the plasma membrane at points referred to as __________.
Answer: adhesion plaques
Page Ref: 245-246
62) In smooth muscle, the actin is bound by __________, a functional parallel to troponin C because it prevents myosin from binding actin.
Answer: caldesmon
Page Ref: 246-247
63) Insect flight muscles contract at frequencies much higher than the stimulation rates they receive from the nerves that innervate them. For this reason, they are termed __________ flight muscles.
Answer: asynchronous
Page Ref: 250
64) Sonic muscles are able to shorten even more than most muscles because of perforations in their __________ that allow the thick filaments to pass into adjacent sarcomeres.
Answer: Z-disks
Page Ref: 252
65) Some muscle tissues undergo trans-differentiation during development, causing them to have novel properties that are not typically associated with muscles, like the billfish __________, for example.
Answer: heater organ
Page Ref: 253
66) Microtubules are important as structural proteins. They may be used to support the cell, as pathways for the movement of motor proteins, and to ensure the even division of chromosomal material during mitosis. Thus, having the ability to regulate the growth of these proteins is necessary for survival. Discuss some of the ways in which microtubule growth can be regulated.
Answer: One of the most basic methods of control is supplying the necessary building blocks for making microtubules. When concentrations of tubulin are low, microtubules tend to shrink. When the concentration is high, their length increases. At concentrations between critical levels, the length stays the same. Even when there is sufficient tubulin, growth is controlled in other ways. GTP is bound to the end of β-tubulin. While it remains a whole GTP, growth continues, but when it is hydrolyzed, the length actually decreases. Lastly, there are microtubule-associated proteins (MAPs) which are a large group of proteins capable of destabilizing and stabilizing microtubule length. They can also regulate ways in which the microtubules interact with each other and the cell. In ectothermic organisms, temperature can also affect formation.
Page Ref: 211-213
67) Actin and myosin interactions are utilized in many types of movement, including the movement generated by muscles. Explain how the movement of myosin down an actin filament can generate contraction of a muscle.
Answer: On the microscopic level, it is important to realize that the actin filaments align with each other and are connected directly or indirectly to some portion of the cell membrane. Myosin is also anchored to proteins inside the cell. When myosin undergoes its cycle of binding, pulling actin, then releasing so it can rebind to a point farther down, it pulls the actin filaments past itself. Since myosin is anchored by proteins in the cell, it is unable to move. This means that eventually the points of actin that are attached to the cell membrane also need to move. As a result, the cell shape is changed, frequently by becoming shorter. If all the muscle cells are attached end to end and they all shorten, then this means the muscle as a whole becomes shorter. It is the shortening of the muscle as a whole that is referred to as a contraction.
Page Ref: 219-223
68) The tension that a sarcomere can produce is related to its length. The same is true for a skeletal muscle, as it is composed of sarcomeres arranged end to end. Explain how the structure of a sarcomere allows the most tension to be generated at an intermediate length, while the longest and shortest lengths will produce very little tension.
Answer: A sarcomere extends from one Z-disk to the next. Actin filaments are attached to the Z-disks, while the myosin bundle is attached at the M-line and stretches out toward the Z-disk. Neither group of proteins reaches completely across the sarcomere. When the myosin heads bind to the actin, they are able to generate tension. Thus, the more myosin is able to form cross-bridges with actin, the more tension can be generated. At the longest lengths, there is very little overlap between actin and myosin, making it difficult for any cross-bridges to form. As the sarcomere shortens, the amount of overlap, and therefore cross-bridge number, begins to increase. There is a small range of maximum overlap before the actin fibers from opposite Z-disks begin to overlap each other. At this point, they prevent the normal formation of cross-bridges, and tension begins to decrease. Thus, the more cross-bridges that are formed, the more tension is generated. At the extremes of length, few cross-bridges exist so that little tension is produced. The intermediate length is the point where the maximum number of cross-bridges formed means the most tension is generated as well.
Page Ref: 226-227
69) In striated muscle, Ca2+ regulates contraction by interacting with troponin and tropomyosin. Explain how Ca2+ is able to regulate the timing of contraction as well as affecting the kinetics of contraction.
Answer: Typically, cytosolic Ca2+ levels are very low. When Ca2+ concentration rises, it can bind to troponin. Troponin is actually composed of three protein subunits: TnC binds to the Ca2+, TnI binds to the actin (inhibiting myosin/actin interactions), and TnT binds to the tropomyosin. It is the tropomyosin that physically blocks the myosin binding site on actin. When Ca2+ binds to TnC, it causes a conformational change so that TnC and TnI become more tightly bound to each other. This, in turn, decreases the interaction between TnI and actin, so that the whole troponin/tropomyosin complex slides over, exposing the myosin binding sites on actin. As long as Ca2+ is present, cross-bridge formation can occur. When Ca2+ is removed from the cytosol, it is also released from TnC, causing the whole complex to return to its original position. Clearly, the point of control is how quickly and tightly TnC binds to Ca2+, thereby allowing the interactions between troponin, tropomyosin, actin, and myosin to occur. By having different isoforms of all these proteins, organisms can regulate these interactions and their sensitivities to physiological variables (pH, temperature, etc.). Ultimately, this affects the time it takes for contractions to occur.
Page Ref: 228-229
70) Skeletal and cardiac muscle are both types of striated muscle. You have been given one type of each sample, but the identifying labels have come off. You know that these muscles have some similarities and some differences in terms of their rate of depolarization, rate of repolarization, and length of action potential. Which of these features would not be useful in identifying the two types of muscle? Which of these features will you use to correctly label the samples? Explain what you would expect to see for skeletal and cardiac muscles for each feature that you use.
Answer: Skeletal and cardiac muscles have similar rates of depolarization, largely because they both use voltage-gated Na+ channels. As a result, this phase of the action potential would not be useful in identifying them. The duration of depolarization is different between the two: it is much longer for cardiac muscle. This is because cardiac muscle uses voltage-sensitive Ca2+ channels that remain open for longer periods of time. As skeletal muscle does not possess these channels, the cells can repolarize more rapidly. This difference relates to the second difference between the two categories of striated muscle: length of action potential. Because cardiac muscle repolarizes slowly, its action potentials also have a longer duration. By the same token, skeletal muscle has an action potential with shorter duration because it repolarizes rapidly. Thus, by stimulating each sample, recording the action potentials, and comparing the rate of repolarization and duration of the action potential, it will be possible to correctly label the two muscle samples.
Page Ref: 234-236
71) Contractions can occur in striated muscle as long as Ca2+ is present in the cytosol. As cytosolic levels of free Ca2+ decrease, so does the ability for myosin to form cross-bridges with actin. This leads to relaxation of the muscle. You have found a novel muscle and are trying to determine if its relaxation processes are regulated in a manner analogous to vertebrate striated muscle. Describe some of the features of Ca2+ regulation that you would expect to see in this novel muscle.
Answer: One of the most common ways to decrease cytosolic Ca2+ levels is to remove the Ca2+. This typically means that Ca2+ will have to move from an area of lower concentration to an area of higher concentration. Under these circumstances, it is necessary to have some sort of energy source. The energy (such as ATP) can be used to pump Ca2+ back into a storage organelle (similar to the sarcoplasmic reticulum) or to the extracellular fluid. These types of pumps are referred to as Ca2+ ATPases in vertebrate skeletal muscle. Alternatively, energy from another concentration gradient could be used to drive the transport of Ca2+. Again, vertebrate muscle exchanges Ca2+ for Na+ (one ion traveling down its gradient and the other traveling up). In both of these cases, Ca2+ would be returned to its origin. In other words, if most of the Ca2+ has come from extracellular sources, most of it will be pumped back out of the cell. The last analogous mechanism I might expect to find would be some type of cytosolic buffer that binds free Ca2+. Once the Ca2+ is bound, then it can no longer interact with the troponin, which allows the muscle to begin its relaxation.
Page Ref: 241-242
72) Discuss some of the important factors responsible for the diversity of muscle types.
Answer: The driving force behind the diversity of muscle types in more complex animals was the trend toward greater body size. Diffusion of respiratory gases work well for small animals, however, simple diffusion cannot meet the demands of larger animals. Thus, the evolution of genes for muscle protein was combined with evolution of primitive respiratory and circulatory systems. For example, in arthropods, muscles control both ventilation and movement.
Vertebrates, however, show the greatest diversity in muscle types. Two rounds of genome duplication occurred in ancestors of vertebrates, resulting in extra copies of genes for muscle proteins, which enabled the evolution of specialized muscle types. As land animals evolved, they had to adapt to challenges of movement on land combined with weight of gravity, and the challenges were met by evolution of muscle genes resulting in muscle specialization and diversification.
Page Ref: 243
73) Smooth muscle, like striated muscle, utilizes Ca2+ as a signal molecule that can allow contraction to occur. However, smooth muscle does not have troponin. Therefore, Ca2+ must interact with other proteins. Describe these relationships and then comment on how this alternate control system affects the rate and duration of smooth muscle contraction. Answer: In smooth muscle, actin is bound by caldesmon, which prevents myosin from forming cross-bridges. When Ca2+ enters the cell, it binds to a cytosolic protein, calmodulin. The calmodulin is then able to bind to caldesmon, and it dissociates from the actin. If [Ca2+] falls, then the Ca2+ -calmodulin-caldesmon complex dissociates, and caldesmon can bind to actin again. If the caldesmon is phosphorylated, it will be unable to bind to actin, regardless of [Ca2+]. This action can dramatically extend the duration of a contraction. In addition to opening up binding sites on actin, Ca2+ also affects the myosin by activating a myosin light chain kinase. MLCK phosphorylates the myosin, increasing its affinity for the actin. It is important to note that other factors may affect contraction states via these second messenger pathways, rather than directly affecting actin or myosin. It should also be noted that phosphorylation is a type of covalent modulation that has a slow and long-lasting time frame, resulting in the slow, long contractions typically seen in smooth muscle (compared to striated muscle).
Page Ref: 246-247
74) Compare smooth and striated muscles in terms of thick and thin filaments, calcium trigger, sarcoplasmic reticulum, regulation of contraction, and rate of contraction. Answer: The thick and thin filaments differ between smooth and striated muscle; in the former, the filaments are not arranged into sarcomeres, whereas in the latter, the filaments are arranged as sarcomeres. In smooth muscle, the calcium trigger is calmodulin, while in striated muscle it is troponin. There is not much sarcoplasmic reticulum in smooth muscle, while it is often abundant in striated muscle. Thick and thin filaments regulate contraction in smooth muscle, while the thin filament is mostly responsible for regulating contraction in striated muscle. When it comes to rate of contraction, the rate is lower in smooth muscle compared to striated muscle.
Page Ref: 248, Table 6.5
Chapter 7 Sensory Systems
1) Which of the following statements is inaccurate with respect to the sensory system of katydids?
A) Katydids’ ears are located in the bend on their front legs.
B) Katydids have excellent hearing.
C) Katydids’ hearing is used to identify mating calls of members of their own species.
D) Katydids cannot detect any echolocation sounds made by different species, such as bats.
Answer: D
Page Ref: 256-257
2) All sensory systems work in the same general way. They transduce an incoming stimulus into changes in membrane
A) potential.
B) capacitance.
C) refractory period.
D) fluidity.
Answer: A
Page Ref: 257
3) Which of the following is NOT one of the steps of sensory processing?
A) transduction of the signal
B) transmission of the signal to the integrating center
C) perception of the stimulus at the integrating center
D) motor response to the signal
Answer: D
Page Ref: 257
4) What defines a cell as an afferent neuron?
A) It has the capacity to respond to environmental stimuli.
B) It is located at the periphery.
C) It has an axon that carries information to integrating centers.
D) It has receptor proteins in its membrane.
Answer: C
Page Ref: 258
5) When a sensory receptor is an afferent neuron, the membrane potential that is initiated by a stimulus is called a
A) generator potential.
B) receptor potential.
C) synaptic potential.
D) action potential.
Answer: A
Page Ref: 258
6) A sensory illusion called paradoxical cold happens when a point heat stimulus is applied to a cold patch of skin, and is perceived as cold, not hot. This illusion happens due to
A) labeled-line pathways.
B) population coding.
C) both heat and cold receptors on the same sensory neuron.
D) lateral inhibition.
Answer: A
Page Ref: 260 and304
7) Select the pair below that does not match.
A) chemoreceptors - detect chemicals
B) photoreceptors - detect light
C) mechanoreceptors - detect magnetic fields
D) thermoreceptors - detect temperature
Answer: C
Page Ref: 259-260
8) For sensory receptor cells, the "threshold of detection" is the weakest stimulus that produces
A) a response.
B) a response 50 percent of the time.
C) a response 100 percent of the time.
D) a maximum response magnitude.
Answer: B
Page Ref: 261
9) In the strategy named “range fractionation,”
A) individual receptor cells are sensitive to a small portion of the possible range of intensities, but multiple receptors cover different parts of the range.
B) individual receptor cells are sensitive to a large portion of the possible range of intensities.
C) there is a decrease in sensory discrimination.
D) populations of receptors hinder sensory discrimination.
Answer: A
Page Ref: 262-263
10) Advantages of populations of receptors, as opposed to individual receptors, include
A) improved sensory discrimination.
B) improved stimulus intensity.
C) improved signal firing rate.
D) all of the above
Answer: A
Page Ref: 262-263
11) When a stimulus is continually applied but the action potential frequency declines, this is called
A) receptor attenuation.
B) receptor acclimation.
C) receptor accommodation.
D) receptor adaptation.
Answer: D
Page Ref: 264
12) In aquatic vertebrates, gustation always involves detecting sensations involved with
A) predators.
B) potential mates.
C) food.
D) all of the above
Answer: C Page Ref: 265
13) Odorant receptors are
A) carbohydrates.
B) proteins.
C) nucleic acids.
D) lipids.
Answer: B
Page Ref: 265
14) Each olfactory neuron expresses __________ odorant receptor protein and each odorant receptor protein can recognize __________ odorant.
A) one; one
B) more than one; one
C) one; more than one
D) more than one; more than one
Answer: C
Page Ref: 267
15) In olfactory receptor cells, signal transduction cascades often follow this order:
A) receptor binding → G-protein activation → cAMP → cell depolarization
B) cell depolarization → increased intracellular Ca2+ → adenylate cyclase activation
C) receptor binding → opening ion channels → G protein activation → cell depolatization
D) cell depolarization → adenylate cyclase → G-protein activation → conformational change
Answer: A Page Ref: 7.8
16) The epithelium of the vomeronasal organ is similar to the olfactory epithelium in which way?
A) Both express the same chemoreceptors.
B) physical location
C) Both activate the same signal transduction pathway.
D) none of the above
Answer: D
Page Ref: 267
17) Bitter and sour tastes are generally associated with A) carbohydrates.
B) proteins.
C) ions.
D) toxic substances.
Answer: D Page Ref: 268
18) In arthropods, the primary olfactory organs are generally located on the A) mandible.
B) tympanum.
C) ommatidia.
D) antennae.
Answer: D Page Ref: 268
19) Among vertebrates, taste buds share certain common features. Which of the following is FALSE?
A) They are onion shaped.
B) They have a pore that opens out to the surface of the body.
C) They have numerous microvilli on the apical surface.
D) They are single neurons.
Answer: D
Page Ref: Fig 7.12
20) Which of the following statements about taste is FALSE?
A) K+ conveys salty.
B) H+ conveys sour.
C) Sugars convey sweet.
D) Amino acids convey umami.
Answer: A Page Ref: 270
21) In the salamander, the sour taste receptor cells function by having an apically localized K+ channel that is blocked by protons. When protons are applied, what happens to the membrane potential and why?
A) Receptor depolarization because K+ permeability, which normally maintains a hyperpolarized resting state, is reduced.
B) Receptor hyperpolarization because H+ ions move into the cell and render it more positively charged.
C) Receptor hyperpolarization because the H+ ions outside the cell make the inside of the cell more negatively charged.
D) Nothing will happen until the G protein is activated.
Answer: A
Page Ref: 270
22) Which of the following lists is in the correct order? Sweet tastes are processed in the following way:
A) receptor binding, gustducin activated, adenylate cyclase activated, K+ channels close.
B) receptor binding, Na+ channels open, cell depolarizes.
C) gustducin activated, Ca2+ channels close, cell hyperpolarizes.
D) transducin activated, PLC activated, Ca2+ levels rise, neurotransmitter released.
Answer: A
Page Ref: Fig. 7.13c, 271
23) Which taste receptor does NOT use a G-protein-coupled receptor for activation?
A) bitter
B) sweet
C) salty
D) umami
Answer: C
Page Ref: Fig 7.13, 271
24) Mechanoreceptors translate mechanical signals into electrical signals when pressure on the cell
A) activates a G protein signal transduction cascade.
B) disrupts stability of the lipid bilayer, causing ions to flow.
C) induces a conformational change in ion channels, allowing ions to flow.
D) induces a change in cell volume that disrupts ion balance.
Answer: C
Page Ref: 274
25) Merkel's disks are used by the visually impaired for reading Braille. One quality of the receptor that allows this is
A) a phasic firing.
B) small receptive field.
C) a special sensitivity to deep pressure on the skin.
D) a large dendritic tree.
Answer: B
Page Ref: 274
26) Without a proprioceptive sense, you would NOT be able to
A) clap your hands behind your back.
B) feel grains of sand on your fingertips.
C) autonomically control blood pressure.
D) sense changes in temperature.
Answer: A
Page Ref: 274
27) You are riding your bicycle over a very bumpy road, reading a street sign far ahead of you. Which sensory inputs are NOT required to accomplish this task?
A) proprioceptors
B) visual inputs
C) inner ear
D) All of the above are required.
Answer: D Page Ref: 274
28) A thin piece of dome-shaped cuticle was found near one of the joints in a cricket leg. When it was removed, the animal could no longer make coordinated movements, but it could still respond to the rapid approach of a predator. This structure is most likely a
A) trichoid sensilla.
B) campaniform sensilla.
C) joint capsule receptor.
D) muscle spindle.
Answer: B Page Ref: 275
29) Ruffini corpuscles are associated with __________ and detect __________.
A) the skin surface; light touch and pressure
B) hair follicles; changes in movement on the skin surface
C) connective tissue of skin; skin stretch
D) deep subcutaneous tissue, muscle, joints; deep pressure and touch
Answer: C Page Ref: 275
30) Mechanoreceptors are important for
A) touch.
B) proprioception.
C) hearing.
D) all of the above Answer: D Page Ref: 273
31) In regards to hair cells involved in vertebrate hearing organs, we know that
A) stereocilia are connected to each other by small fibers.
B) mechanosensitive ion channels at the tips of stereocilia are all closed at rest.
C) the 9 + 2 arrangement of stereocilia allow for free bending to improve sound resolution.
D) their bending always causes an increase in firing in the primary afferent.
Answer: A Page Ref: 278
32) Which of the following structures from the vertebrate inner ear is NOT part of the vestibular apparatus?
A) ampulla
B) utricule
C) saccule
D) cochlea
Answer: D
Page Ref: 281
33) The hair cells of the mammalian cochlea are contained in the
A) vestibular duct.
B) tympanic membrane.
C) round window.
D) organ of Corti.
Answer: D
Page Ref: 286
34) The small bones in the mammalian middle ear are called:
A) malleus, incus, stapes.
B) stapes, ossicle, tectorus.
C) malleus, otolith, statocyst.
D) utricle, saccule, ampulla.
Answer: A
Page Ref: Fig. 7.28
35) If the orientation of your ears were changed so that your right ear still faced forward but your left ear faced backward, how would your ability to locate the direction of an auditory stimulus change?
A) improved ability to distinguish left from right
B) improved ability to distinguish above from below
C) improved ability to distinguish front from back
D) There would be no improved ability at all.
Answer: C Page Ref: 287
36) Which of the following choices is FALSE? Mammalian rods and cones differ in that rods
A) have fewer types of photopigment than cones.
B) have a slower response time than cones.
C) function better than cones in bright light.
D) integrate signals over a longer period than cones.
Answer: C Page Ref: 289
37) Which of the following choices is FALSE? The chromophore
A) absorbs energy from photons.
B) is a derivative of vitamin D.
C) is covalently linked to a member of the opsin gene family.
D) plays a role in photoreceptor sensitivity to different colors.
Answer: B Page Ref: 290
38) Which of the following choices is FALSE regarding rhabdomeric photoreception?
A) The absorption of light leads to cell hyperpolarization.
B) The opsins signal through a Gq protein.
C) A phospholipase C signal transduction cascade is activated.
D) Diacylglycerol affects the activity of a nonselective cation channel.
Answer: A
Page Ref: 291
39) Improving the resolving power of the compound eye would require
A) increasing the number of ommatidia.
B) increasing the size of each ommatidium.
C) decreasing the size of the pinhole opening on each ommatidia.
D) decreasing the thickness of the cornea.
Answer: A Page Ref: 293
40) Which eye structure constricts or dilates to control the amount of light that enters the eye?
A) iris
B) pupil
C) retina
D) lens
Answer: A Page Ref: 294
41) The focal point is the
A) point between the center of the lens and the retina.
B) point where light waves converge after passing through the lens.
C) small region in the center of the retina responsible for high-acuity vision.
D) narrow band of the electromagnetic spectrum that contains visible light.
Answer: B
Page Ref: 295
42) To generate an optimal visual image, the focal point must fall on the
A) lens.
B) fovea.
C) retina.
D) cornea.
Answer: C Page Ref: Fig. 7.38
43) Why is vision sharpest in the fovea?
A) It has more rods.
B) It has more cones.
C) There is less interference with overlying cells.
D) It contains the focal point.
Answer: C Page Ref: 296
44) What is the main difference between "on" and "off" region receptive fields?
A) signal processing at the photoreceptor
B) the type of neurotransmitter released by the photoreceptor
C) the nature of the response of the bipolar cell to glutamate
D) the presence of horizontal cells
Answer: C
Page Ref: 298
45) In animals with binocular vision, it is true that
A) neurons from the retina of the right eye project to the left lateral geniculate nucleus.
B) neurons responding to the right visual fields project to the left lateral geniculate nucleus.
C) neurons of the nasal retina project to the left lateral geniculate nucleus.
D) neurons of the temporal retina project to the left lateral geniculate nucleus.
Answer: B
Page Ref: Fig. 7.43
46) Some species of fish are able to produce electrical discharges. These fish
A) produce discharges continuously from their electric organ
B) produce only weak discharges of approximately 1 volt
C) have a specialized electric organ of highly derived nerve and muscle cells known as electrocytes
D) are known as strongly electric fish.
Answer: C
Page Ref: 306, Box 7.3
47) In response to a stimulus, a signal transduction pathway is initiated, which ultimately leads to the opening or closing of __________.
Answer: ion channels
Page Ref: 257
48) Sensory cells that respond to more than one class of stimulus are called __________ receptors.
Answer: polymodal
Page Ref: 260
49) __________ are a kind of receptor that respond to extremely strong stimuli, including those that may cause tissue damage.
Answer: Nociceptors
Page Ref: 260
50) Stimulus intensity is normally coded by action potential_____________.
Answer: frequency
Page Ref: 261
51) To help discriminate the location of a touch stimulus, neurons at the center of the receptive field can inhibit those at the edge, a process known as __________.
Answer: lateral inhibition
Page Ref: 261
52) The top of a sensory cell's dynamic range can be limited by the firing frequency of the primary afferent neuron. The maximum frequency is set by the __________ period.
Answer: refractory
Page Ref: 263
53) The __________ law describes the logarithmic relationship between stimulus magnitude and perceived stimulus intensity.
Answer: Weber-Fechner
Page Ref: 263-264
54) In the vertebrate olfactory system, the olfactory receptor cells have one end in the olfactory epithelium, and the other end makes synapses with neurons in the __________ of the brain.
Answer: olfactory bulb
Page Ref: 265
55) Terrestrial vertebrates detect pheromones using an organ called the __________ organ.
Answer: vomeronasal
Page Ref: 267
56) In humans, tastes can be grouped into one of five classes, which are __________. (list all five)
Answer: salty, sweet, bitter, sour, umami
Page Ref: 268
57) In terrestrial vertebrates, taste receptor cells are clustered into groups known as __________.
Answer: taste buds
Page Ref: 268
58) In vertebrates, olfactory receptor cells are bipolar sensory neurons, but taste receptor cells are __________.
Answer: epithelial cells
Page Ref: 272
59) There are two main types of mechanoreceptor proteins: epithelial sodium channels and __________.
Answer: transient receptor potential channels
Page Ref: 273
60) Touch and pressure receptors can be broadly grouped into three categories: tactile receptors, proprioceptors, and __________.
Answer: baroreceptors
Page Ref: 274
61) ____________ are found in vertebrates and invertebrates, and are responsible for monitoring the position of the body.
Answer: proprioceptors
Page Ref: 274
62) A tympanal organ functions as an insect __________.
Answer: ear
Page Ref: 277
63) Invertebrates have organs called __________ that detect the orientation of their bodies with respect to gravity.
Answer: statocysts
Page Ref: 276
64) Fish, larval amphibians, and adult aquatic amphibians have cup-shaped organs called __________ that consist of mechanosensory hair cells to detect water movements such as those caused by potential predators.
Answer: neuromasts
Page Ref: 280
65) In carp, the inner ear is connected to the swim bladder by a series of bones called __________.
Answer: Weberian ossicles
Page Ref: 282
66) The organ of the inner ear of mammals that contains the hair cells is called the __________. Answer: organ of Corti
Page Ref: 286
67) The compound called __________ can stimulate cold-sensitive neurons. Answer: menthol
Page Ref: 304
68) The compound called __________ can stimulate warm-sensitive neurons. Answer: capsaicin
Page Ref: 304
69) In the mammalian inner ear, inner hair cells detect sounds, while outer hair cells __________. Answer: amplify sounds
Page Ref: 286
70) Compound eyes are composed of many __________.
Answer: ommatidia
Page Ref: 293-294
71) Researchers are trying to determine the cause of circadian rhythm disruption in modern societies. They measured the hormone ________________ , which is associated with sleep-wake cycles in humans. Levels of this hormone are high at night and lower during the day
Answer: melatonin Page Ref: 303 (Box 7.2)
72) List the four necessary steps that are required for sensory reception. Different receptors are used to detect different stimuli: Briefly describe three examples of stimulus modality.
Answer: The four steps for sensory reception are 1) reception of the signal, 2) transduction of the signal, 3) transmission of the signal to integrating center, and 4) perception of the stimulus at the integrating signal. There are numerous examples of stimulus modality. Chemoreceptors detect chemical signals; therefore, they enable us to smell and taste. Mechanoreceptors are stimulated by pressure and movement, so senses of smell, touch, and balance fall under this category. Photoreceptors sense light, thus our vision depends on photoreception.
Page Ref: 257, 259-260
73) Discuss how pheromones are used by (nonhuman) animals to communicate with members of their own species or with other species. Provide at least three examples to support your answer.
Answer: Pheromones are chemicals that animals release to communicate with members of their own species. Many pheromones are considered to be sex pheromones because they elicit a response in the opposite sex, often being used to attract mates. For example, farmers have found that if they spray honeybee pheromones on crops, the presence of the pheromones enhances pollination of their crops. Biocontrol agents also include pheromones. Fruit farmers hang dispensers of pheromones from the apple codling moth, which is a pest of apples. Female moths release the pheromone to attract mates, but as the pheromone becomes widespread as a result of the dispensers, males have a hard time locating the females and mating success is decreased. Interspecies communication using pheromones has also been observed in nature. Some orchid species release chemicals that mimic insect pheromones; the pheromones attract insect pollinators to the orchids and enhances the flowers' reproductive success.
Page Ref: 269 (Applications 7.1)
74) Both the olfactory system and the gustatory system in vertebrates work by processing chemoreceptive signals. However, there are several differences between them. Describe/explain three differences.
Answer: 1. Olfactory receptor proteins are always coupled to G proteins, while gustatory receptor proteins have a variety of signal transduction mechanisms.
2. Olfactory neurons express only a single olfactory protein per cell, unlike gustatory receptor cells, which express more than one kind of receptor protein.
3. Olfactory receptor cells are bipolar sensory neurons, while gustatory receptor cells are epithelial cells that release neurotransmitter onto a primary afferent neuron.
Because a single taste neuron can synapse with more than one taste receptor cell, this suggests that coding of taste information is complex. It is unlikely that the coding of taste information works in a fashion by which a single taste is coded by a single neuron. This is different than processing in the olfactory system, where each neuron expresses only a single receptor protein, and therefore it is more likely that each neuron codes for a single olfactory sensation. The coding for tastants is probably very different than the coding for odorants.
Page Ref: 272
75) Briefly describe lateral inhibition. Why is it useful? Draw a figure if necessary.
Answer: Lateral inhibition is a process by which sensory activity at one location inhibits the activity of adjacent neurons. In other words, neurons that are stimulated will "turn off" neighboring neurons. The purpose of lateral inhibition is to enhance sensory contrast and improve edge detection. For example, imagine a pinprick on the surface of the skin. The source of the stimulus (i.e., the point of the pin) is very small, but its pressure on the skin will cause the skin around the pin tip to bend a little as well, which stimulates neighboring receptive fields. Without the process of lateral inhibition, the perception would be that a much larger object was touching the skin, and this would be inaccurate. Instead, lateral inhibition "turns off" neighboring cells (i.e., sensory cells around the pin), and more accurately codes for stimulus size by clearly coding for the stimulus edge.
Page Ref: 262 and 298, 299, Figures 7.4 and 7.41, 7.42
76) How does the mammalian eye focus an image? In your description, name the important physical structures in image formation, define the focal point, and explain what accommodation is and why it is important.
Answer: To create a clear image, light entering the eye must converge on a single point called the focal point, and this focal point must fall on the retina. However, light rays entering the eye are not always entering from the same direction. That is, light rays entering from a distant object are parallel when they strike the eye, but light rays entering from a nearby object are not parallel but are instead divergent. These light rays are bent once they hit the cornea and lens, and the light rays will converge. However, based on the difference in angles between distant and nearby objects, the light rays converge at different points beyond the lens. Light rays from distant objects have a short focal length (focal length: the distance from the center of a lens to its focal point). Light rays from nearby objects have a long focal length. In order to adjust the focal length and force the focal point onto the retina, a process called accommodation, the lens must change shape.
Additional information:
∙ The cornea and the lens have a convex shape, which causes light rays to bend toward each other. While both of these structures contribute to image formation, the cornea is not capable of changing shape to fine-tune image formation.
∙ The point where the light converges after passing through the lens is called the focal point.
Accommodation is the process by which the eye changes its focal length to ensure that the focal point falls on the retina. In mammals, this happens when the lens changes shape. This change is a function of the contraction or relaxation of the ciliary muscles of the eye, to cause the lens to become more rounded or flattened, respectively.
Page Ref: 295-296
77) Generally, how do sensory neurons encode stimulus intensity? What is the dynamic range of a sensory neuron? How does range fractionation improve the dynamic range?
Answer: Sensory neurons change their firing rates to encode stimulus intensity. A higher intensity stimulus generally results in a higher frequency of firing, while a lowerintensity stimulus results in a lower frequency of firing. The dynamic range of a neuron is the range between the minimum and maximum signals that can be discriminated. At some point, the intensity of the stimulus will be so low in magnitude that the sensory neuron will not fire reliably. The "threshold of detection" is defined as the weakest stimulus that produces a response in a receptor 50% of the time, and it forms the lowest limit of the neuron's dynamic range. At the top of the dynamic range, the neuron has reached its highest firing frequency, and cannot increase any more regardless of an increase in stimulus intensity. This saturation point forms the highest limit of the cell's dynamic range. Range fractionation happens when different sensory cells are sensitive to different (but overlapping) portions of the dynamic range. Using a strategy in which groups of sensory neurons work together within a single sensory organ, this effectively allows the organ to code for a much wider range of stimulus intensities.
Page Ref: 263-4, Fig. 7.6
78) It is late at night, and you are at the library doing some last-minute studying for your comparative physiology exam. You suddenly feel hungry, and you head to the vending machine to buy a snack. Explain the role of the following sensory structures/organs, and give an example of how/when they will be active during this task.
a. Merkel cell
b. Gustatory receptors (choose one)
c. Macula of a utricle
d. Cone photoreceptor
Answer: Answers to this can be somewhat creative in giving examples for the use of these receptors.
a. Merkel cells are used for fine tactile discrimination, and may be used for handling coins, opening a bag of food, touching the food, etc. (see page 274).
b. Gustatory receptors: Depending on the type of snack, the student may describe the function of any of the receptors from page 271 (salty, sour, bitter, umami, sweet). For example, a bag of chips may be purchased, and the taste bud would be active with a particular focus on the reception of a "salty" signal. Sodium from salty food enters the receptor cell through a sodium channel, which causes cell depolarization. This depolarization results in calcium influx and consequent neurotransmitter release. The afferent neuron is activated.
c. The utricle is a part of the vestibular apparatus that is sensitive to linear acceleration. It would be active during forward walking motion. (see page 281 Fig. 7.24a)
d. Cone photoreceptors in vertebrates detect color. Therefore, these would be active when looking at all the different packages in the vending machine. (see page 289-290, Figure 7.31, and Table 7.21)
Page Ref: 274, 281, 289-290
79) Why is it so difficult to localize sound with only one ear? How does having two ears help to localize sound?
Answer: Sound is localized in two main ways. One way is through a TIMING DIFFERENCE. For example, if a sound is produced on the right side of the head, the sound will reach the right ear before it reaches the left. The brain can process this time lag, and the sound is perceived, correctly, as coming from the right. Sound is also localized through an INTENSITY DIFFERENCE. That is, when the same signal coming from the right passes through the head to reach the left ear, the sound intensity is altered. The brain can process this intensity difference, and the sound is perceived, correctly, as coming from the right. Two ears are required to process these differences, and that is why it is difficult to localize sound with only one ear.
Page Ref: 287
80) If all sensory signals are eventually transduced into the common action potential, then how do receptors encode stimulus modality? Give an example.
Answer: One way in which sensory systems can code for stimulus modality is described by the theory of labeled lines. Since most sensory receptors are maximally sensitive to only one type of stimulus, and a sensory receptor is part of (or synapses with) a particular afferent neuron, signals in that afferent neuron must represent a specific stimulus modality. In other words, nociceptive afferent neurons are active ONLY in response to nociceptive stimuli, and thermal afferent neurons are active ONLY in response to thermal stimuli. In a common example, we know that the optic nerve transmits the signal "light" whenever the eye is stimulated, even if the stimulus is pressure on the eyeball.
The assumption with the labeled-line theory is that there is a discrete pathway from a sensory cell to the integrating center, but sensory connections are not always this simple. For example, polymodal receptors (e.g., ampullae of Lorenzini), which are sensitive to a variety of different stimuli, cannot code in the basic way laid out by the labeled-line theory. In this case, the afferent neuron may discriminate modality based on the firing pattern (e.g., high-frequency bursts instead of tonic firing). Additionally, neighboring polymodal receptors, with slightly different sensitivities to the various stimuli, may work together to send a coded signal to the afferent neuron. This type of "cross-fiber coding" is not well understood.
Page Ref: 260
Chapter 8 Functional Organization of Nervous Systems
1) Unlike humans, bottlenose dolphins do not suffer from the effects of sleep deprivation. Why?
A) Dolphins "catnap" throughout the day, so they don't need to go into deep sleep
B) In dolphins, one half of their brain sleeps while the other half of the brain remains active.
C) Sleep is required to maintain brain function in humans, but not in dolphins.
D) Dolphins take turns waking each other up, so all have a chance to sleep.
Answer: B
Page Ref: 310-311
2) Integrating centers typically contain large numbers of A) interneurons.
B) sensory neurons.
C) efferent neurons.
D) motor neurons.
Answer: A
Page Ref: 311
3) The axons of afferent and efferent neurons are usually organized into structures called A) nuclei.
B) ganglia. C) nerves.
D) tracts.
Answer: C
Page Ref: 313
4) How can you explain the substantial lag between a signal and response in the phylum Porifera?
A) Lag occurs because sponges are asymmetrical
B) Lag occurs because sponges show no cephalization
C) Lag occurs because action potentials in cells of sponges are slow compared to action potentials in neurons.
D) Lag occurs because the signal has to be very strong in order to see any response
Answer: C
Page ref: 313-314
5) Invertebrates possess a
A) solid ventral nerve cord.
B) hollow ventral nerve cord.
C) solid dorsal nerve cord.
D) hollow dorsal nerve cord.
Answer: A
Page Ref: 317
6) In vertebrates, substances from the blood can access the central nervous system by
A) gap junctions.
B) pinocytosis.
C) catalyzed transport.
D) all of the above
Answer: C
Page Ref: 318
7) In the vertebrate brain and spinal cord, white matter consists of __________ and gray matter consists of __________.
A) axons and myelin; cell bodies and dendrites
B) sensory neurons; motor neurons
C) axons and myelin; ganglia
D) the dorsal horn; the ventral horn
Answer: A Page Ref: 319
8) In the vertebrate spinal cord, the dorsal horn is associated with __________ neurons, and the ventral horn is associated with __________ neurons.
A) motor; sensory
B) inter; sensory
C) afferent; efferent
D) spinal; cranial
Answer: C
Page Ref: 319
9) The ventricles of the vertebrate brain contain
A) neurons.
B) glia.
C) cerebrospinal fluid.
D) dura mater.
Answer: C
Page Ref: 320
10) Among other things, the hindbrain is responsible for
A) regulation of involuntary behaviors such as breathing.
B) coordination of visual and auditory information.
C) regulation of eating and reproduction.
D) conversion of short-term memories into long-term memories.
Answer: A
Page Ref: 320
11) Relative to other major groups of vertebrates, mammals and birds both have an enlarged
A) forebrain.
B) midbrain.
C) hindbrain.
D) dorsoventricular ridge.
Answer: A Page Ref: 324
12) The following structures of the mammalian nervous system, from posterior to anterior, are laid out in the following order:
A) spinal cord, medulla oblongata, pons, cerebellum.
B) spinal cord, pons, cerebellum, medulla oblongata.
C) medulla oblongata, spinal cord, cerebellum, pons.
D) pons, cerebellum, spinal cord, medulla oblongata.
Answer: A Page Ref: 325
13) What does the midbrain do in fish and amphibians?
A) It coordinates reflex responses to auditory and visual stimuli.
B) It detects the presence of pheromones.
C) It is responsible for maintaining body posture.
D) It controls heart rate and blood pressure.
Answer: A Page Ref: 325
14) In nonmammalian vertebrates, the optic lobes are located in the
A) forebrain.
B) midbrain.
C) hindbrain.
D) spinal cord.
Answer: B Page Ref: 326
15) Which of the following structures is NOT included in the limbic system?
A) amygdala
B) hypothalamus
C) olfactory bulb
D) cerebellum
Answer: D Page Ref: Fig. 8.14
16) The limbic system is associated with
A) emotion.
B) motivation.
C) decision-making.
D) all of the above
Answer: D Page Ref: 327-328
17) How many distinct layers does the mammalian cortex have?
A) 6
B) 4
C) 3
D) 2
Answer: A Page Ref: 329
18) In the mammalian brain, the __________ lobe is involved with visual processing.
A) frontal
B) parietal
C) occipital
D) temporal
Answer: C
Page Ref: 329
19) In a newly discovered vertebrate, the area in the somatosensory cortex devoted to body part
A is larger than the area devoted to body part B. This means that body part A
A) is bigger than body part B.
B) has more sensory neurons.
C) is evolutionarily older.
D) has more motor control.
Answer: B
Page Ref: 329, Fig. 8.18
20) The efferent branch of the peripheral nervous system is composed of the __________ and __________ divisions.
A) somatic motor; autonomic
B) visceral; emotional
C) sympathetic; parasympathetic
D) autonomic; involuntary
Answer: A
Page Ref: 331
21) The autonomic nervous system can be differentiated into three branches. Which of the following is NOT one of them?
A) enteric
B) sympathetic
C) parasympathetic
D) limbic Answer: D Page Ref: 331
22) The __________ nervous system is most active during periods of stress or physical activity, while the __________ nervous system is most active during periods of rest.
A) sympathetic; parasympathetic
B) parasympathetic; sympathetic
C) voluntary; involuntary
D) parasympathetic; enteric Answer: A Page Ref: 331
23) The __________ nervous system is sometimes referred to as the "fight or flight" nervous system.
A) autonomic
B) somatic
C) parasympathetic
D) sympathetic Answer: D Page Ref: 331
24) Most sympathetic pathways originate in the __________ regions of the CNS.
A) thoracic and lumbar
B) hindbrain and sacral
C) cranial
D) postganglionic
Answer: A Page Ref: 332
25) In the sympathetic and parasympathetic nervous systems, the preganglionic neuron releases the neurotransmitter
A) acetylcholine.
B) nicotine.
C) glycine.
D) epinephrine.
Answer: A
Page Ref: 333, Fig. 8.20
26) What receptors do the neurosecretory chromaffin cells of the adrenal medulla express?
A) adrenergic
B) muscarinic cholinergic
C) nicotinic cholinergic
D) glutamatergic
Answer: C Page Ref: 335, Fig. 8.20
27) The simplest reflex arc, containing only a primary afferent and an effector neuron, is sometimes referred to as
A) monosynaptic.
B) bineural.
C) convergent.
D) voluntary.
Answer: A Page Ref: 338
28) Central pattern generators do NOT control
A) rhythmic behaviors.
B) motor pathways.
C) reflex arcs.
D) locomotion.
Answer: C Page Ref: 339
29) The locomotor pattern generator is located in the
A) spinal cord.
B) brainstem.
C) autonomic nervous system.
D) peripheral nervous system.
Answer: A Page Ref: 340
30) The basic mechanism for short-term sensitization begins with
A) decreased neurotransmitter release.
B) increased presynaptic calcium.
C) increased expression of CREB-1.
D) increased potassium conductance.
Answer: B Page Ref: 343
31) Which structure is important for the formation of long-term memory in mammals?
A) hippocampus
B) hypothalamus
C) cortex
D) medulla oblongata
Answer: A Page Ref: 346
32) Which of the following statements is true about learning?
A) It refers to the retention and retrieval of stored information.
B) It occurs only in vertebrates.
C) It normally represents a permanent change.
D) It occurs as the result of nervous system plasticity.
Answer: D Page Ref: 343
33) The hippocampus is important for the
A) formation of long-term memories.
B) regulation of body temperature.
C) Integration of sensory information.
D) maintenance of body posture.
Answer: A Page Ref: 346
34) Hearing a loud and unexpected noise in the night activates the
A) sympathetic nervous system.
B) parasympathetic nervous system.
C) somatic nervous system.
D) enteric nervous system.
Answer: A Page Ref: 331
35) Homeostasis is maintained by the
A) hypothalamus.
B) cerebral cortex.
C) hippocampus.
D) limbic system.
Answer: A
Page Ref: 327
36) This brain structure is greatly reduced in mammals relative to other vertebrates.
A) cerebellum
B) midbrain
C) forebrain
D) isocortex
Answer: B
Page Ref: 325-326, Fig. 8.12
37) The brains of taxi drivers in London, England, differ from the brains of other people This can be attributed to
A) brain plasticity, because brains have the ability to alter their structure and function as a result of learning and/or experience.
B) the hippocampus of London taxi drivers increasing with age
C) accident of birth; the people driving taxis in London were born with a smaller hippocampus, which then increased in size over time.
D) A and B
Answer: A
Page Ref: 347, Applications 8.3
38) __________ neurons relay information from integrating centers such as the brain to effector organs like muscles or glands.
Answer: Efferent
Page Ref: 311
39) __________ is the evolutionary trend that describes the concentration of nervous tissue and sense organs at one end of the body.
Answer: Cephalization
Page Ref: 312
40) In vertebrates, the __________ nerves exit directly from the braincase.
Answer: cranial Page Ref: 317
41) The protective layer of connective tissue surrounding the brain and spinal cord is called the __________.
Answer: meninges (or singular meninx)
Page Ref: 317
42) The vertebrate central nervous system is physiologically separated from the rest of the nervous system by the __________.
Answer: blood-brain barrier
Page Ref: 318
43) The three main regions of the vertebrate brain are the prosencephalon, the mesencephalon, and the __________.
Answer: rhombencephalon
Page Ref: 320
44 In most vertebrates, except the mammals, the __________ contains the regions that are involved in interpreting visual information.
Answer: midbrain
Page Ref: 320, 325
45) In mammals, the midbrain can be grouped together with the pons and medulla oblongata, and is called the __________.
Answer: brainstem
Page Ref: 326
46) The mammalian cerebral hemispheres are connected by a mass of white matter called the __________.
Answer: corpus callosum
Page Ref: 326
47) is a structure of the limbic system that is involved in emotional responses, such as fear or aggression.
Answer: amygdala Page Ref: 327
48) The __________ is essentially a relay station that filters sensory information and forwards it to the cortex.
Answer: thalamus
Page Ref: 328
49) In species with cortical folds, the outer regions of the folds are called __________ and the inner grooves are called __________.
Answer: gyri; sulci
Page Ref: 328
50) The hormone _______________ is secreted by the pineal gland.
Answer: melatonin Page Ref: 328
51) The somatosensory cortex and primary motor cortex are organized __________. That is, each part of the cortex corresponds to the specific part of the body that it governs.
Answer: topographically
Page Ref: 330, Fig. 8.18
52) The only organ controlled by efferent motor neurons is __________.
Answer: skeletal muscle
Page Ref: 337
53) All vertebrate motor neurons release the neurotransmitter __________.
Answer: acetylcholine
Page Ref: 337
54) The __________ nervous system is sometimes referred to as the "rest and digest" nervous system.
Answer: parasympathetic
Page Ref: 331
55) The tendency to reduce the magnitude of a response following repeated stimulation is called __________.
Answer: habituation
Page Ref: 343
56) An increase in a response following exposure to a strong or noxious stimulus is called __________.
Answer: sensitization
Page Ref: 343
57) NMDA and AMPA receptors both bind the neurotransmitter __________.
Answer: glutamate
Page Ref: 349
58) Split-brain syndrome follows from severing the __________.
Answer: corpus callosum
Page Ref: 327
59) In its protective role, the blood-brain barrier becomes an obstacle in delivering therapeutic drugs to specific regions of the brain in the treatment of a variety of brain disorders. Describe what the blood-brain barrier is made of, and how different compounds are capable of crossing it.
Answer: The blood brain barrier is formed by tight junctions between the endothelial cells lining the brain capillaries. It prevents materials from leaking out of the bloodstrea and into the central nervous system. These cells do not perform pinocytosis. Despite the tight junctions, there are still ways that compounds can cross the blood-brain barrier, including:
1. Dissolving in the membrane. Small lipid-soluble molecules such as ethanol and some barbiturate drugs can cross directly into the central nervous system.
2. Catalyzed transport mechanisms (protein exchanger, channel, pump) allow the brain to take up circulating nutrients such as glucose and amino acids.
3. In some areas of the brain, the blood-brain barrier is more permeable. In particular, the regions around the pineal gland, the pituitary gland, and parts of the hypothalamus are quite permeable, allowing secreted molecules such as hormones to leave the brain and enter the circulatory system.
Page Ref: 318-319
60) There is a large variation in brain size among vertebrates, and the relationship between brain size and brain complexity has always been a fascinating topic of study. What is meant by the term encephalization quotient (EQ)? What information does EQ provide, what are two problems with using EQs, and is there a better way to address the questions of brain complexity?
Answer: EQ is the ratio of the observed brain mass to the expected brain mass. When we compare EQ quotients, humans have the largest EQs, followed by some cetaceans such as dolphins, and then various species of primates. Social animals and carnivores have higher EQs than solitary and herbivorous animals. These findings suggest that EQs provide some information about cognitive capacity, and in general, behavioral complexity correlates well with EQ. Using EQs becomes problematic because the values obtained depends on the taxa used to obtain the regression line. The data used to generate the regression is also problematic because each point in the regression represents one entire species. As we know, there is much variation in body mass of different individuals in a species. To further complicate matters, even the mass of individuals can change dramatically over time, thus changing the EQ.
Recent research by Dr. Herculano-Houzel uses a technique, which directly measures the number of neurons in the brain. The nuclei of brain cells are stained, which allows one to distinguish nuclei of neurons from non-neural glial cells. Dr. Herculano-Houzel’s results comparing rodents and primates with similar-sized brains reveals that primate brains have more neurons per unit area, which may explain the higher cognitive capacity of primates. In addition, more neurons per unit area may also facilitate the formation of more synapses. Thus, counting neuron numbers holds some promise to potentially provide more knowledge about brain cognition and complexity.
Page Ref: 322-323 (Box 8.1)
61) Describe five differences between the actions of the parasympathetic and sympathetic nervous systems on the same effector organs. For example, the parasympathetic system causes urine release from the bladder, while the sympathetic system causes urine retention. Answer: Effector organ
Pupil of eye
Parasympathetic effect
Sympathetic effect
Constricts Dilates
Heart Slows heart rate
Arterioles
Digestive tract
Bladder
Sweat glands
Bronchioles of lungs
Adipose tissue
Page Ref: 334 Table 8.2
Increases rate and force of contraction
None Constricts
Increased motility and secretion
Release of urine
Decreased motility and secretion
Retention of urine
General sweating Localized sweating
Constricts Dilates
None
Fat breakdown
62) What are the three main anatomical differences between the parasympathetic and sympathetic nervous systems?
Answer: Sympathetic
Originate in the thoracic and lumbar regions of the spinal cord
Ganglia are found in a chain that runs close to the spinal cord
Single preganglionic neuron synapses with 10 or more postganglionic neurons
Page Ref: 333-335
Parasympathetic
Originate in the hindbrain or in the sacral region of the spinal cord
Ganglia are located close to the effector organ
Preganglionic neuron synapses with three or fewer postganglionic neurons
63) What four major brain structures are included in the limbic system? Where is it located in the vertebrate brain? What does the limbic system do?
Answer: The limbic system is part of the forebrain, and lies on the border between the cortex and the rest of the brain. The four main structure included in the limbic system are (1) the amygdala, (2) the hippocampus, (3) the hypothalamus, and (4) the olfactory bulbs. The limbic system is often called the "emotional brain" because it controls emotions such as pleasure and fear, as well as decision-making, motivation, sex drive, hunger, and memory. The hypothalamus, within the limbic system, is also responsible for regulation of homeostasis, including body temperature, fluid balance, blood pressure, and body weight.
Page Ref: 327-328
64) If the central pattern generator for a human walking is located in the spinal cord, then is the brain required at all for successful walking behavior? Justify your answer.
Answer: A central pattern generator is a subset of neurons that can maintain spontaneous rhythmic output in the absence of sensory input. Therefore, the basic neural control for coordinating the action of the limbs during walking is housed in the spinal cord, and it can maintain its own activity without input from the brain. However, in a natural environment, inputs from the brain ARE required for a variety of other tasks associated with successful locomotion. For example, the cortex and brainstem are required to initiate locomotion. In other words, while the central pattern generator can maintain its own activity without input from the brain, it does, in fact, need a brain "trigger" in order to start.
The cerebellum is required for balance and coordination to prevent the human from falling over. The brainstem controls the speed of locomotion. The cortex assists in regulating gait based on visual inputs such as obstacles and uneven terrain. Even though the central pattern generator can control basic muscular coordination, other sensory inputs and higher integrative inputs are required for successful walking behavior in a real setting
Page Ref: 339-341
65) List five ways that efferent motor pathways can be distinguished from autonomic pathways.
Answer: Efferent motor neurons control only one type of effector organ-skeletal muscle. Autonomic pathways control many organs. The cell bodies of motor neurons are located in the CNS, never in ganglia outside the CNS. Efferent motor pathways are monosynaptic, meaning that there is only a single synapse between the CNS and the skeletal muscle. This means that efferent motor neurons can be very long. Autonomic pathways are polysynaptic. Synapse morphology is different between autonomic and motor pathways. At the neuromuscular junction, a motor neuron splits into a cluster of axon terminals that branch out over the motor end plate. Autonomic neurons have several synaptic varicosities arranged in series like a string of beads. The size of the synaptic cleft is different. The synaptic cleft between the motor neuron and the muscle is much narrower than that between autonomic neurons and their effector cells. The nature of the neurotransmitter is different. All vertebrate motor neurons release acetylcholine at the neuromuscular junction, whereas sympathetic neurons release epinephrine and parasympathetic neurons release acetylcholine. The response of the effector organ differs. The effect of acetylcholine on skeletal muscle is always excitatory, whereas autonomic neurons may be excitatory or inhibitory.
Page Ref: 337
66) Succinctly explain how ocean acidification can affect the behavior of fish, such as the orange clownfish (Amphiprion percula)
Answer: Clownfish live on coral reefs in close association with sea anemones. Clownfish larvae are strongly attracted to the scent of sea anemones and the scent of leaves of specific tropical rainforest trees, which are indicative of a suitable coral reef habitat. On the other hand, they show avoidance of leaves from specific tropical swamp trees, which indicate an undesirable swampy habitat. Acidified oceans can have a detrimental effect on the survival of clownfish larvae because their behavior changes: Larvae raised in acidified ocean water become very attracted to scents of swamp trees (unsuitable habitat) and their attraction for suitable coral reef habitats decreases. Another consequence of ocean acidification is the clownfish’s attraction to the scent of predators instead of showing predator avoidance behavior. Research shows that ocean acidification causes this change in behavior of clownfish, and it is caused by a disruption in brain homeostasis A decrease in extracellular Clinterferes with chloride channels, more specifically the GABA-A receptor. The results of the research demonstrate that a small change in brain chemistry can affect behavior, and, as shown in the example of the orange clownfish, may lead to a decrease in survival of the species.
Page Ref: 342 (Challenges to Homeostasis 8.2)
Chapter 9 Circulatory Systems
1) In mammals, heart size tends to be proportional to body weight while heart rate is inversely proportional to body weight. What is the most probable explanation for pygmy shrews having unusually large hearts but an unusually slow heart rate? A) Pygmy shrews are very active so they need large hearts.
B) It is possible that the heart rate of shrews has reached its absolute limitation, so a large heart can pump more blood with each beat.
C) Since pygmy shrews are tiny, their heart size differs from other mammals, and their heart rate is slow when they are at rest.
D) The heart size of pygmy shrews varies, depending on latitude.
Answer: B Page Ref: 356-357
2) Which of the following is NOT one of the essential components of a circulatory system?
A) a pump
B) a system of tubes
C) a fluid
D) oxygen
Answer: D Page Ref: 358
3) Which of the following fluids is NOT circulated by the cardiovascular system?
A) plasma
B) blood
C) hemolymph
D) lymph Answer: D Page Ref: 360
4) How does the dorsal blood vessel of the earthworm pump blood?
A) contractile skeletal muscle surrounding the vessel
B) peristalsis
C) contractile chamber
D) It doesn't pump blood. Blood flow is passive. Answer: B Page Ref: 363
5) How many hearts does an octopus have?
A) 1
B) 2
C) 3
D) 4
Answer: C P a
e R e f : 363 6)
The general term for blood vessels that carry blood away from the heart is
A) aorta.
B) artery.
C) vein.
D) atrium.
Answer: B Page Ref: 367
7) Tetrapods have two circuits within their circulatory system. The one that pushes blood through the lungs is called the
A) pulmonary circuit.
B) systemic circuit.
C) capillary circuit.
D) aortic circuit.
Answer: A Page Ref: 370
8) Arthropod hearts share some common features. Which of the following is NOT a feature of all arthropod hearts?
A) Hemolymph is pumped out of the heart via arteries.
B) Hemolymph returns to the heart via holes called ostia.
C) The heart fills through forces of suction.
D) Myogenic action potentials lead to contraction.
Answer: D Page Ref: 364-365
9) The vertebrate heart muscle is known as
A) pericardium.
B) epicardium.
C) myocardium.
D) endocardium.
Answer: C Page Ref: 377
10) In fishes and amphibians, spongy myocardium receives oxygen from
A) blood in the heart chambers.
B) coronary arteries.
C) trachea.
D) pericardial fluid.
Answer: A Page Ref: Figure 9.21 369
11) Fish hearts consist of __________ chambers arranged in a series.
A) two
B) three
C) four
D) five
Answer: C Page Ref: 378
12) In the bony fish, all heart chambers are contractile except the
A) sinus venosus.
B) atrium.
C) ventricle.
D) bulbus arteriosus.
Answer: D Page Ref: 378
13) In most non-crocodilian reptiles, the ventricle is divided into three chambers. Which of the following is NOT one of the chambers?
A) cavum venosum
B) cavum pulmonale
C) cavum cardiacum
D) cavum arteriosum
Answer: C Page Ref: 379
14) Vasoconstriction is the result of the contraction of smooth muscle of the
A) tunica intima.
B) tunica media.
C) tunica externa.
D) tunica lumena.
Answer: B Page Ref: 368
15) What type of capillary is normally found in the kidney?
A) continuous
B) fenestrated
C) sinusoidal
D) paracellular
Answer: B Page Ref: 369
16) Excluding capillaries in the central nervous system, the least permeable type of capillary is the
A) continuous capillary.
B) fenestrated capillary.
C) sinusoidal capillary.
D) occluding capillary.
Answer: A
Page Ref: 369
17) How do veins prevent the backflow of blood?
A) gravity
B) pressure
C) valves
D) bulk flow
Answer: C
Page Ref: 370
18) What differentiates a closed circulatory system from an open circulatory system?
A) the presence of a heart
B) the presence of a circulating fluid
C) the presence of vessels
D) dcirect contact of circulating fluid with tissues
Answer: D
Page Ref: 359
19) What is believed to be the major evolutionary pressure in the development of closed circulatory systems?
A) transport of oxygen
B) transport of immune factors
C) transport of hormones
D) transport of glucose
Answer: A
Page Ref: 366
20) What is NOT one of the functional distinctions between arteries and veins?
A) Veins always carry deoxygenated blood.
B) Veins usually have a thinner vessel wall.
C) Veins are easily stretched.
D) Veins often contain one-way valves.
Answer: A
Page Ref: 370
21) How do substances move across capillaries?
A) diffusion
B) through pores
C) transcytosis
D) all of the above
Answer: D
Page Ref: 368-369
22) Based on the law of bulk flow, what is the unit for "flow"?
A) volume
B) volume/time
C) time
D) force/area
Answer: B Page Ref: 373
23) Small increases in blood vessel __________ can lead to big decreases in vessel resistance.
A) length
B) radius
C) pressure
D) force
Answer: B Page Ref: 375
24) Angiogenesis refers to
A) damage to blood vessels.
B) synthesis of blood vessels.
C) genetic analysis of blood vessels.
D) the ontogeny of the vascular system.
Answer: B Page Ref: 370
25) What is hypoxia?
A) absence of oxygen
B) low levels of oxygen
C) normal levels of oxygen
D) high levels of oxygen
Answer: B Page Ref: 370
26) The end-diastolic volume is
A) the maximum volume of blood in the ventricle.
B) the maximum volume of blood in the atrium.
C) the minimum volume of blood in the ventricle.
D) the minimum volume of blood in the atrium.
Answer: A Page Ref: 384
27) In the mammalian heart, the valves open and close because
A) they are under neural control.
B) they are under myogenic control.
C) changes in chamber pressure cause them to open and close.
D) all of the above
Answer: C Page Ref: 384
28) In the cardiac cycle of mammals and birds, the ventricles fill mostly as a result of
A) passive blood flow from the atrium.
B) forces of suction from ventricular expansion.
C) atrial contraction.
D) high ventricular pressure.
Answer: A
Page Ref: 385
29) Which of the following possibilities is incorrect? During the mammalian cardiac cycle, the right ventricle contracts less forcefully than the left because
A) the distance the blood must travel is shorter.
B) of the low total resistance of the pulmonary circuit.
C) the blood vessels of the lungs are delicate.
D) the capillary bed offers high resistance.
Answer: D
Page Ref: 385-386
30) How do cardiomyocytes communicate with one another?
A) neurotransmitters
B) gap junctions
C) synapses
D) tight junctions
Answer: B
Page Ref: 386
31) Cardiac pacemaker cells have an unstable resting membrane potential as the result of an unusual __________ current.
A) magnesium
B) sodium
C) chloride
D) calcium
Answer: B
Page Ref: 387
32) The rising phase of a cardiac pacemaker action potential is caused by a __________ current.
A) potassium
B) sodium
C) chloride
D) calcium
Answer: D
Page Ref: Figure 9.31
33) The rising phase of the action potential of a cardiac cardiomyocyte is caused by a __________ current.
A) potassium
B) sodium
C) chloride
D) calcium
Answer: B
Page Ref: Figure 9.34
34) Electrical signals move through the mammalian heart in a particular order. Which order is correct?
A) SA node; internodal pathway; AV node; bundle of His; Purkinje fibers
B) AV node; SA node; internodal pathway; bundle of His; Purkinje fibers
C) SA node; AV node; internodal pathway; Purkinje fibers; bundle of His
D) bundle of His; Purkinje fibers; internodal pathway; AV node; SA node
Answer: A
Page Ref: Figure 9.35
35) Cardiac output is a function of heart rate and
A) blood pressure.
B) vasoconstriction.
C) heart size.
D) stroke volume.
Answer: D Page Ref: 391
36) Norepinephrine has the following effect on pacemaker cells:
A) increased sodium influx.
B) increased potassium influx.
C) increased ATPase activity.
D) decreased calcium influx.
Answer: A Page Ref: 387
37) Tachycardia is a term that refers to
A) lower than normal heart rate.
B) abnormal rhythm.
C) uncoordinated contraction of the heart.
D) higher than normal heart rate.
Answer: D
Page Ref: 392 (Applications 9.2)
38) When there is an immediate requirement for increased oxygen to a particular body tissue in the systemic circuit,
A) arterioles will dilate in that area.
B) capillaries will increase in number.
C) capillaries will decrease in size.
D) arterioles will constrict in that area.
Answer: A Page Ref: 396
39) Which of the following does NOT cause vasodilation?
A) increased carbon dioxide
B) increased nitrogen
C) increased hydrogen
D) increased nitric oxide
Answer: B
Page Ref: 397, Table 9.1
40) During periods of activity, when the heart rate is rapid, the mean arterial pressure in humans is
A) 2/3 diastolic pressure and 1/3 systolic pressure.
B) 1/3 diastolic pressure and 2/3 systolic pressure.
C) 1/2 diastolic pressure and 1/2 systolic pressure.
D) approximately equal to systolic pressure.
Answer: C
Page Ref: 400
41) Total flow in the vertebrate circulatory system can be expressed as the total pressure change divided by
A) total peripheral resistance.
B) total volume.
C) total length.
D) total time.
Answer: A Page Ref: 401
42) Blood volume is maintained by the
A) kidney.
B) liver.
C) gallbladder.
D) spleen.
Answer: A
Page Ref: 403
43) What is hydrostatic pressure?
A) pressure exerted by a fluid at rest
B) pressure exerted by a fluid in motion
C) resistive forces generated by fluid viscosity
D) high blood pressure
Answer: A Page Ref: 407
44) What is edema?
A) accumulation of interstitial fluid in any tissue
B) accumulation of interstitial fluid in the blood
C) overactivity of the lymphatic system
D) a condition of the lungs
Answer: A Page Ref: 406
45) What physiological or morphological characteristics prevent a giraffe from developing cerebral edema while drinking?
A) one way valves in the artery leading to the head
B) low blood pressure
C) highly elastic blood vessels near the brain
D) low heart rate
Answer: C Page Ref: 409
46) Which of the following is FALSE? Mammalian hemocytes are involved in
A) nutrient transport.
B) phagocytosis.
C) immune defense.
D) hormone secretion.
Answer: D Page Ref: 361
47) What types of blood cells are involved in immunity?
A) thrombocytes
B) platelets
C) leukocytes
D) erythrocytes
Answer: C Page Ref: 361
48) Hematopoiesis is the production of
A) blood cells.
B) blood vessels.
C) blood plasma.
D) bone marrow.
Answer: A Page Ref: 400
49) During aerobic exercise in vertebrates
A) sympathetic stimulation of heart decreases.
B) blood pressure changes only slightly.
C) higher brain centers are not involved.
D) the activity of the parasympathetic nervous system increases.
Answer: B Page Ref: 411
50) Unicellular organisms rely on the process of __________ to transport substances throughout the body.
Answer: diffusion Page Ref: 357
51) Sponges do not have a true circulatory system, but they can propel water through their bodies using flagellated __________.
Answer: choanocytes Page Ref: 362
52) In the decapod crustacean, blood returns to the heart through small holes called __________.
Answer: ostia
Page Ref: 364
53) In the tetrapod circulatory system, the right side of the heart is responsible for the __________ circuit, and the left side is responsible for the __________ circuit.
Answer: pulmonary; systemic
Page Ref: 371
54) The primary pump in chambered hearts is called the __________.
Answer: ventricle
Page Ref: 359
55) In open circulatory systems, the circulating fluid comes into direct contact with tissues in open spaces called __________.
Answer: sinuses/hemocoel
Page Ref: 360
56) Cardiac contraction is called __________.
Answer: systole
Page Ref: 384
57) In jawed vertebrates, the large artery leading from the heart to the body is called the __________.
Answer: aorta
Page Ref: 366
58) The direct connection between two arteries in the circulatory system is called an __________.
Answer: anastomosis
Page Ref: 368
59) Vertebrate blood vessels have complex walls. The smooth muscle of the __________ layer of the blood vessel causes vasoconstriction.
Answer: tunica media
Page Ref: 368
60) Capillaries empty into __________.
Answer: venules
Page Ref: 368
61) _____________ capillaries are the most porous of all capillaries, and are found in very specialized organs, such as the liver.
Answer: Sinusoidal
Page Ref: 369
62) In mammals, the __________ is the main blood vessel leading from the heart to the lungs.
Answer: pulmonary artery
Page Ref: 370
63) In mammals, the __________ is the main blood vessel leading from the lungs to the heart.
Answer: pulmonary vein
Page Ref: 370
64) In tetrapods, the __________ side of the heart pushes blood through the pulmonary circuit.
Answer: right Page Ref: 373
65) The law of bulk flow quantifies the relationship between flow, pressure, and __________.
Answer: resistance
Page Ref: 373
66) The ridge that separates the two ventricles in the mammalian heart is called the intraventricular __________.
Answer: septum
Page Ref: 381
67) __________ are positioned at points along vasculature to prevent blood from flowing backwards.
Answer: Valves
Page Ref: 370, Fig. 9.3
68) In vertebrates other than fish, the cardiac pacemaker cells are located in an area of the right atrium called the __________.
Answer: sinoatrial node
Page Ref: 386
69) The term for a decrease in heart rate is __________.
Answer: bradycardia
Page Ref: 391
70) In an EKG of a normal cardiac rhythm, the P wave and T wave (respectively) indicate __ and _____ _____.
Answer: atrial depolarization; ventricular repolarization
Page Ref: 391
71) When there is more blood in the ventricle of the heart, the heart will contract more forcefully and increase stroke volume. This phenomenon is known as the __________.
Answer: Frank-Starling effect
Page Ref: 394
72) Baroreceptors are important for the regulation of __________.
Answer: blood pressure
Page Ref: 402
73) An osmotic pressure that is due to proteins is termed __________.
Answer: oncotic pressure
Page Ref: 406
74) The main function of vertebrate erythrocytes is the storage and transport of __________.
Answer: oxygen Page Ref: 361-362
75) There are different types of pumping structures in animal circulatory systems. Describe the three different types. How is one-way flow ensured?
Answer: All circulatory systems have some type of pumping structure that propels fluids around the system. There are three main types of pumping structures in animal circulatory systems.
a. External pump: Organs not strictly associated with the circulatory system, such as skeletal muscle, can be used to develop pressure gradients. Contraction and relaxation of skeletal muscles, such as during movements of the legs, can alternately compress and expand a blood vessel, forcing fluid along its pressure gradient. A one-way valve guarantees one-way flow.
b. Peristaltic contraction: This rhythmic wave of muscle contraction along a blood vessel wall proceeds in a coordinated fashion from one end to the other, similar to squeezing toothpaste from a tube. Because the contractions usually occur in a specific direction, the flow is usually one-way even when no valves are present.
c. Contractile chambers, such as the vertebrate heart: Muscular contraction of the walls of the chamber increase pressure, and when this pressure exceeds that in the rest of the circulatory system, blood will flow down the pressure gradient. Blood does not flow backwards during the contraction because a one-way valve prevents such flow.
Page Ref: Figure 9.3, 359
76) In birds and mammals, blood pressures are different between the pulmonary and systemic circuits. Which one is greater? Why is the difference advantageous?
Answer: In birds and mammals, the pulmonary and systemic circuits are completely separated. One advantage of this complete separation is that pressures can be different in each circuit. When blood flows to the lungs, the capillaries in the lungs must be very thin to permit gas exchange. However, if blood flows too forcefully through them, fluid will leak through the capillary walls. When this fluid accumulates, it increases the diffusion distance and reduces the efficiency of gas exchange. Therefore, a lowpressure pulmonary circuit is advantageous. The systemic circuit however, can be very long, especially in very large animals. High blood pressure is required to force blood all the way through it. Having two separate pressures allows the differing demands to be met.
Page Ref: 371-372
77) Poiseuille's equation makes a variety of assumptions regarding the physics of blood flow through the circulatory system. Give Poiseuille's equation, and list the violations for each of its four variable parameters.
Answer: a. Poiseuille's equation is given as: Q = ΔΡπr4/8Lη?
b. Poiseuille's equation can be thought of the same way one can think about liquid moving through a drinking straw. The resistance of liquids within the straw is a function of the length of the tube (L), the radius of the tube (r), and the viscosity of the liquid (η). This resistance is given as: R = 8Lη/ πr4.
c. By substituting the resistance relationship into the law of bulk flow, Q = ΔP/R, you can derive Poiseuille's equation. Based on the terms given in the equation, we know that flow can be affected by the pressure gradient, the radius of the vessel, the length of the vessel, and the viscosity of the fluid. The radius of the vessel (changed by vasoconstriction or vasodilation) can have a huge impact on the flow of the circulating fluid throughout the system, more than some of the other factors, because it is raised to the fourth power.
d. Poiseuille's equation makes a variety of assumptions regarding the physics of the circulatory system. For example, it assumes that the blood vessels are unbranched and rigid, and that the flow is steady. Violations to the equation include:
i. The circulatory system is branched, in both convergent and divergent ways, which makes the length of the system complicated. This violates the simple function of length (L).
ii. Vessel walls are flexible, or "compliant," in response to pressure, which makes the calculation of 'r' complicated. Moreover, there are some vessels that stretch easily when exposed to pressure (highly compliant), while others stretch less. Also, the compliance of a blood vessel is not constant, but becomes less compliant at higher pressures. Finally, blood vessels take time to stretch. Together, these factors add up to the violation of the assumption r
iii. In larger vessels, pressure of blood flow is pulsatile, increasing when the heart contracts. Also, flow can sometimes be turbulent (instead of laminar), mainly in the heart and some vessel branching points. Additionally, the velocity profile of the blood is not identical across the diameter of the vessel. Instead, flow is slower near the walls, and faster near the center. Overall, flow is complex, and these issues add up to a violation of pressure (P).
iv. Finally, blood is a mixture of components with different viscosities. It acts as a non-Newtonian fluid, which means that its viscosity varies depending on the size of the tube that it flows through. The components of blood tend to separate in smaller blood vessels. That is, blood cells get swept into the high velocity flow in the center of the vessel, while it is mainly plasma at the walls, leading to "low viscosity" and "high viscosity" parts of the vessel. In even smaller vessels, blood cells take up almost the whole diameter of the vessel. Cells change shape to squeeze through, and blood vessels tend to stick to the vessel walls and to each other, leading to high viscosity in those areas. Therefore, fluid is a complex mixture, and viscosity is variable, which violates η.
Page Ref: Box 9.1 374
78) Beginning with all chambers of the heart in the "relaxed" phase, describe the cardiac cycle in mammals, with systole and diastole of the atria and ventricles. For each time point in the cycle you select, state the following:
Whether the atria and ventricles are contracting or relaxing
Whether the AV valves and semilunar valves are closed or open
∙ Whether the pressure in the atria and ventricles is high or low
Answer: i. The heart begins with all chambers relaxed. The AV valves are open and the semilunar valves are closed. Low pressure in the heart causes the blood to flow passively into the atria and ventricles.
ii. The atria contract. The ventricles are relaxed. Additional blood flows into the ventricles. Semilunar valves are closed. AV valves are open.
iii. The ventricles contract. The atria relax. The AV valves close. The semilunar valves are still closed. Pressure rises within the ventricles.
iv. High pressure within the ventricles causes the semilunar valves to open. Blood is ejected from the ventricles into circulation.
v. The ventricles relax. The atria are still in diastole. The semilunar valves close. Pressure is low in the atria and ventricles.
vi. The low pressure allows blood from circulation to flow into the atria and ventricles, and the cycle begins anew.
Page Ref: 384 Figure 9.29
79) The contractility of the heart can be modified through the release of norepinephrine from sympathetic neurons. A cAMP-mediated signal transduction cascade is activated that activates a protein kinase. List and describe the four ways that a protein kinase can affect the contractility of the heart.
Answer: i. Phosphorylation of L-type calcium channels on the cell membrane allows increased Ca2+ into the cell in response to depolarization.
ii. Phosphorylation of proteins in the membrane of the sarcoplasmic reticulum causes it to release more Ca2+ in response to an action potential.
iii. Phosphorylation of myosin increases the rate of myosin ATPase, increasing the rate of cross-bridge cycling and the speed of muscle contraction
iv. Phosphorylation of the sarcoplasmic reticulum Ca2+ ATPase enhances Ca2+ reuptake into the sarcoplasmic reticulum, increasing the rate of relaxation.
v. All together, these four mechanisms cause the cardiomyocytes to contract faster and more strongly in response to sympathetic stimulation, increasing the stroke volume of the heart.
Page Ref: 391, 394
80) Doctors use electrocardiograms to diagnose heart conditions. What information does an EKG provide?
Answer: The EKG provides the heart rate of the patient. The heart rate can be calculated by computing the R-R interval (time between each heartbeat), which gives the number of seconds per heartbeat, then you take the inverse and convert to minutes. The R-R value may vary from beat to beat, so the heart rate variability (HRV) values may be indicative of diabetes, high blood pressure, and coronary heart disease.
The EKG also shows the cardiac rhythm. Abnormal rhythms include atrial fibrillation where atria contract in an uncontrolled fashion (patient not in immediate danger), ventricular fibrillation where ventricles contract in an uncontrolled way (potentially deadly because of ineffective delivery of blood to tissues), and atrioventricular blocks where abnormal signaling between atria and ventricles occurs. AV blocks differ in severity and the worse severity may be deadly if an artificial pacemaker is not installed
Page Ref : 392-393 (Applications 9.2)
81) What is the Frank-Starling effect, and why is it important during periods of increased enddiastolic volume? What would happen if the Frank-Starling effect didn't exist?
Answer: The Frank-Starling effect describes the effect whereby greater filling of the ventricles results in a greater ventricular contraction. It allows the ventricles, effectively, to "autoregulate" stroke volume, so that it can pump effectively. It allows the heart to automatically compensate for increases in the amount of blood returning to the heart. If the Frank-Starling effect didn't exist, and the stroke volume of the heart was always constant, then in a situation in which venous return is increased, there would be "leftover" blood in the heart after each contraction. This extra blood would build up over time, increasing in volume, until the heart was so distended that contraction would be ineffective.
Page Ref: 394-395
82) During the flight or fight response, sympathetic pathways cause arterioles to contract. If this is true, how is it possible to increase blood flow to areas that require additional oxygen, such as skeletal muscle?
Answer: While vasoconstriction is useful for areas that don't require additional oxygen, such as the gut and kidneys, skeletal muscles need extra oxygen. While the sympathetic pathways dictate that arterioles contract, local paracrine factors released by muscles and the heart, such as nitric oxide and adenosine, signal the vessels to dilate, and the local factors override the sympathetic signal.
Page Ref: 398
83) When arterial blood reaches the capillary bed, the fluid from the capillary moves into the interstitial spaces. After arterial blood has passed through the capillaries into the venous network, fluid will flow back again into the blood from the interstitial fluid. Give the Starling principle of fluid exchange, and use this principle to explain the movement of fluids at the capillary bed.
Answer: The Starling principle of fluid exchange is given as: NFP = (Pcap - Pif) - (πcap - πif), where NFP is the net filtration pressure, Pcap is the hydrostatic pressure in the capillary, Pif is the hydrostatic pressure in the interstitial fluid, πcap is the osmostic pressure in the capillary, and πif is the osmotic pressure in the interstitial fluid.
Arterial blood has high pressure as it approaches the capillary bed, and this pressure is the major force pushing fluids from the blood into the interstitial spaces. Because continuous capillaries are permeable only to small molecules, plasma proteins and blood cells remain behind in the blood as fluids are pushed out, resulting in the blood having a higher osmotic pressure than the interstitial fluid. After the blood has moved through the capillaries, the osmotic pressure due to proteins (termed "oncotic pressure") has increased in the capillaries, and tends to suck fluids back into the blood. Moreover, because the hydrostatic pressure of the blood declines as it moves from the arterial to venous end of the capillary bed, the osmotic pressure exceeds hydrostatic pressure, and this also tends to allow fluids to reenter the blood.
Page Ref: 405-406
84) What are the five major types of leukocytes in vertebrate blood, and what are their functions?
Answer: a. Leukocytes are involved in the immune response.
b. Neutrophils engulf damaged cells and pathogens by phagocytosis.
c. Eosinophils deliver cytotoxic chemicals and enzymes that kill parasites. They are also involved in allergic reactions.
d. Basophils leave the circulatory system and accumulate at sites of infection. They release toxic chemicals to kill pathogens in the interstitial space. They are involved in inflammation.
e. Macrophages are phagocytic cells that engulf pathogens and dead cells. They mature from monocytes, which are white blood cells that circulate only briefly in the blood.
f. Lymphocytes are present in multiple types. Some make antibodies (B cells), and some facilitate an immune response by secreting molecules that activate other lymphocytes (helper T cells). Others secrete cytotoxic agents that kill invaders or dying cells (killer T cells).
Page Ref: 361
85) How will the baroreceptor reflex function to help maintain mean arterial pressure after a blood donation?
Answer: The baroreceptor reflex is triggered by baroreceptors, which are stretch-sensitive mechanoreceptors located in the walls of many of the major blood vessels. The most important of these are located in the carotid artery and aorta, although there are also some in the walls of pulmonary arteries and in the heart. These baroreceptors, under normal conditions, send a steady stream of action potentials to the CNS. The cardiovascular control center in the medulla oblongata integrates these inputs, and sends out efferent signals via autonomic neurons that control heart rate, stroke volume, and vasomotor and venomotor tone, thus influencing blood pressure. Increased blood pressure causes arterial walls to stretch, increasing baroreceptor firing frequency, which, through the integrating activity of the medulla oblongata, decrease output of sympathetic fibers, resulting in vasodilation. In combination with an increase in parasympathetic output, this will additionally result in decreased cardiac contraction force and rate. This lowers blood pressure.
Page Ref: 402-403
86) Define the term hypertension, describe the two classes of hypertension, and explain how hypertension can be treated.
Answer: Hypertension means chronic high blood pressure where sustained systolic blood pressure >139 mm Hg and diastolic pressure > 89 mm Hg, measured at rest. Primary hypertension does not have one clear cause; it is a combination of genetic risk combined with environmental influences. Secondary hypertension is caused by endocrine disorders, which cause kidneys to retain fluid.
Sometimes a change in lifestyle is effective in treating hypertension. These changes include losing weight, exercising regularly, and decreasing sodium intake. If a lifestyle change does not work, then drugs may be used to decrease blood pressure. Some drugs vasodilate arterioles to decrease peripheral resistance. Other drugs have a diuretic effect causing water loss at the kidneys, which decreases both blood volume and blood pressure. Betablockers are used to decrease heart rate and to reduce the force/strength of heart contractions.
Page Ref: 404-405 (Challenges to Homeostasis 9.3)
Chapter 10 Immune Systems
1) The natural hosts for the myxoma virus are
A) South American jungle rabbits
B) North American rabbits
C) European rabbits
D) native Australian rabbits.
Answer: A Page Ref: 415
2) The myxoma virus is transmitted from one rabbit to another
A) in drinking water.
B) by predators.
C) by blood-sucking insects.
D) by interaction with other herbivores.
Answer: C
Page Ref: 415
3) An animal can increase its risk of contracting a pathogen as a result of
A) a cut in the skin
B) a decrease in secretion of mucus.
C) interactions with symbiotic organisms.
D) A and B
Answer: D
Page Ref: 415
4) Lymphoid stem cells give rise to
A) natural killer cells
B) mast cells
C) basophils
D) platelets and B cells
Answer: A
Page Ref: 416
5) Which cells are named for their function?
A) lymphocytes
B) phagocytes, macrophages
C) granulocytes
D) T cells and B cells
Answer: B
Page Ref: 416
6) The innate immune system
A) is a collection of defenses that is found in all animals, including sponges
B) remains ready until it is needed, and responds without specificity to the type of pathogen
C) is also referred to as an induced immune system
D) can increase the intensity of the immune response when a pathogen is detected a second time
Answer: B
Page Ref: 417
7) What do macrophages and neutrophils have in common?
A) Both kill pathogens by phagocytosis.
B) Both are polymorphonuclear cells.
C) Both are derived from lymphoblasts.
D) Both secrete cytotoxic agents.
Answer: A
Page Ref: 417 (Table 10.1)
8) Invertebrates such as grasshoppers have
A) both innate and adaptive immune systems.
B) both innate and adaptive immune systems, but the adaptive system is more important.
C) only an innate immune system
D) only an adaptive immune system.
Answer: C
Page Ref: 417
9) Which of the following statements is correct?
A) From an evolutionary perspective, the adaptive immune system is older than the innate immune system.
B) Viruses contain a cell wall composed of B-glucans.
C) Phagocytic cells secrete cytotoxic compounds and initiate apoptosis.
D) Once animals detect pathogen-associated molecular patterns, an immune response is initiated.
Answer: D
Page Ref: 418
10) Which of the following statements is correct with respect to toll-like receptors (TLRs)?
A) Some of the TLRs found in fish are homologous to those in humans.
B) Mice and humans have the same TLRs since both are mammals.
C) Early deuterostomes, such as sea urchins, do not possess any TLRs.
D) A and C
Answer: A
Page Ref: 419
11) Which are the main types of phagocytes involved in the innate immune response?
A) macrophages and neutrophils
B) macrophages and basophils
C) neutrophils and B cells
D) basophils and eosinophils
Answer: A
Page Ref: 420
12) Neutrophils
A) are the least abundant of the leukocytes in mammals
B) stain dark blue by the histological H&E stain.
C) use both phagocytosis and secretion of antimicrobial agents to destroy microbes.
D) B and C
Answer: C
Page Ref: 420-421
13) Macrophages
A) secrete cytokines that initiate changes in other cells.
B) are capable of ingesting neutrophils
C) are referred to as polymorphonuclear (PMN) cells.
D) A and B
Answer: D
Page Ref: 421
14) Which of the following statements is correct?
A) Opsonization is a process that targets a pathogen for phagocytosis by covering it with soluble sugars.
B) The complement system includes a group of proteins that circulate in an inactive form and become activated when they detect molecular signatures of pathogens.
C) Mannose-binding lectin is a carbohydrate that is secreted by the liver
D) Macrophages secrete monocytes
Answer: B Page Ref: 422
15) An inflammatory response
A) is observed when tissue has been damaged and there is increased blood flow to the area.
B) often causes an immediate drop in temperature of the damaged tissue.
C) is manifested in the same way in all animals.
D) A and C
Answer: A Page Ref: 424
16) The adaptive immune system can bolster a specific immune response as a result of
A) antigens.
B) antibodies.
C) creation of clone cells.
D) immunological memory.
Answer: D Page Ref: 425
17) ______________ immunity includes processes involving antibodies or complement proteins.
A) Cellular
B) Humoral
C) Nuclear
D) Interstitial
Answer: B Page Ref: 425
18) What is the major advantage of the adaptive immune system?
A) The intensity of the immune response is decreased when a foreign agent is detected a second time because the immune system recognizes the foreign agent from a previous encounter
B) It has higher specificity than the innate system because it can identify which immune cells produce the correct antibodies and amplify those cells
C) All features of the adaptive immune system are the same in all vertebrates.
D) A and B are equally advantageous.
Answer: B Page Ref: 425
19) The parasite Plasmodium, which causes malaria, is a A) protist.
B) virus
C) bacteria
D) nematode
Answer: A
Page Ref: 426
20) Which of the following statements best describes how humans are infected by the malaria parasite?
A) In the hemolymph of the mosquito, the gametocytes mature, migrate to the salivary glands, and are injected into the host when the mosquito feeds.
B) In the mosquito’s digestive tract the parasite produces oocysts, which migrate to the salivary glands, and are injected into the host when the mosquito feeds.
C) In the mosquito’s digestive tract the parasite produces gametocytes, which migrate to the salivary glands, and are injected into the host when the mosquito feeds.
D) In the mosquito’s digestive tract the parasite develops into infective sporozoites, which travel to the salivary glands, and are injected into the host when the mosquito feeds.
Answer: D
Page Ref: 426
21) Which of the following cells produce antibodies?
A) T cells
B) NK cells
C) B cells
D) V and D cells
Answer: C
Page Ref: 428
22) Jawless fish lack immunoglobulins and use __________________ to recognize non-self macro molecules.
A) variable antigen receptors
B) variable lymphocyte receptors
C) C region receptors
D) recombination signal receptors
Answer: B
Page Ref: 429
23) Mammals have ___ key classes of immunoglobulins.
A) 3
B) 4
C) 5
D) 6
Answer: C
Page Ref: 429
24) Which of the following statements is correct with respect to the sites of synthesis of B and T cells.
A) In bony fish, B cells are produced in the kidney or spleen.
B) In most vertebrates, B cells are produced in body cells, but in different locations of the body.
C) Jawless fish produce T cells in the thymus.
D) Bony and cartilaginous fish produce T cells in the gill region, referred to as the thymoids.
Answer: A
Page Ref: 430
25) Which of the following cells are involved in cellular immunity?
A) lymphocytes
B) phagocytes
C) leucocytes
D) A and B
Answer: D
Page Ref: 430
26) Which of the following are the two most common lymphocyte types?
A) B cells and T cells
B) B cells and mast cells
C) T cells and mast cells
D) B cells and NK cells
Answer: A
Page Ref: 430
27) Major histocompatibility complex (MHC) genes are
A) polygenic.
B) polygenic and polymorphic
C) polygenic and monomorphic
D) monogenic and monomorphic
Answer: B
Page Ref: 431
28) What activates memory cells?
A) an encounter with an antigen
B) an encounter with mast cells
C) cells that have undergone partial differentiation
D) stem cells
Answer: A
Page Ref: 434
29) For over a decade the blood of a mammal contains a certain cell type in its immune system. One day the cell recognizes an antigen that it had previously encountered, binds to it, and triggers an immune response. What kind of cell would react in this way?
A) T cell
B) monocyte
C) eosinophil
D) memory cell
Answer: D
Page Ref: 433
30) After encountering an antigen, an animal has memory cells that can produce antibodies quickly. In the absence of the antigen
A) memory cells die off
B) memory cells don’t produce antibodies at all
C) memory cells produce few antibodies
D) memory cells are totally inactivated.
Answer: C
Page Ref: 434
31) Which of the following immune cells are segregated to the correct specific region?
A) plasma cells / paracortical region
B) macrophages / lymphoid follicle
C) T cells / paracortical region
D) B cells / medullary region
Answer: C
Page Ref: 435
32) How are antibodies transferred from mother to offspring in birds?
A) Offspring obtain antibodies from the egg yolk
B) Offspring obtain antibodies from the egg whites
C) Offspring obtain antibodies from the mother’s regurgitated food
D) A and B
Answer: D
Page Ref: 438
33) Stress is known to impact immune function. Which of the following hormones are produced at higher rates under stressful conditions?
A) glucagon
B) glucocorticoids
C) testosterone
D) estrogen
Answer: B
Page Ref: 439
34) What evidence lends support to the hypothesis that in a species, males generally have lower immunotolerance than females?
A) Males die younger.
B) When males are treated with testosterone implants, a decrease in immunotolerance is observed.
C) When males are treated with cholesterol implants, an increase in immunotolerance is observed.
D) The slower the maturity rate, the lower the immunotolerance
Answer: B
Page Ref: 440
35) The immunocompetence -handicap hypothesis
A) lends support to the sexual selection hypothesis, which states that males with the most elaborate displays provide an honest signal of good health.
B) suggests that males with superior immunocompetance are the ones with the least elaborate displays but the longest lifespan.
C) suggests that the immune system of males competes for resources with sexually selected elaborate displays, and those males with superior immunocompetence can withstand the costs of developing elaborate displays.
D) A and C
Answer: D Page Ref: 440
36) The novel host, which is devastated by myxomatosis, is the ________________. Answer: European rabbit Page Ref: 415
37) In animals, the first line of defense against pathogens is the ______________. Answer: skin or external surface Page Ref: 415
38) Blood cells are derived from ______________ stem cells.
Answer: hematopoietic Page Ref: 416
39) When the _______________ binds to its pathogen-associated molecular pattern, the cell triggers a signal transduction pathway.
Answer: pattern-recognition receptor Page Ref: 418
40) Mannose-binding lectin is an example of an ____________. Answer: opsonin Page Ref: 421
41) Natural killer cells are derived from ______________. Answer: lymphoblasts Page Ref: 423
42) _______________ genes are found in both plants and animals, suggesting an ancient evolutionary history. Answer: Defensin Page Ref: 423
43) The term _____________________ refers to the adaptive immune system producing a rapid and dramatic immune response the second time an antigen is encountered.
Answer: immunological memory Page Ref: 425
44) Insecticides and anti-malarial drugs have been used for decades to fight malaria with limited success. Currently, research is focusing on genetic modification and creation of __________________ mosquitos that cannot spread the parasite.
Answer: transgenic or genetically modified Page Ref: 427
45) Malaria is caused by a parasite belonging to the genus ________________.
Answer: Plasmodium Page Ref: 426-427
46) Immunoglobulin diversity arose through gene ________________. Answer: recombination Page Ref: 428
47) alert immune cells of the presence of a pathogen. Answer: Antigen-presenting cells Page Ref: 431
48) T cells that cause other cells to respond are referred to as ________________. Answer: helper T cells Page Ref: 433
49) Before a lymphocyte encounters an antigen, it is referred to as a ___________________. Answer: naive lymphocyte Page Ref: 434
50) cells play an important role in allergic reactions. Answer: Mast Page Ref: 435
51) Explain how the use of biological control to decrease the population of introduced European rabbits in Australia relates to immunology.
Answer: The natural host for the myxoma virus is the South American jungle rabbit, and because this host and pathogen co-evolved together, jungle rabbits are only very mildly affected by the pathogen. If the myxoma virus is to be used as a biological control agent, the virus needs to be highly virulent to the new host and the virus needs an appropriate vector (for example biting insects such as mosquitoes or fleas) to effectively transmit it from one rabbit to another. European rabbits were a novel host to the myxoma virus, and the virus, spread by blood-sucking insects, was so effective as a biological control agent, it initially killed 99.8% of the European rabbit population in Australia. Over the next seven years, however, the death rate of rabbits declined as the immune system of these rabbits became less sensitive to the pathogen, due to natural selection. Understanding how species adapt immunologically to pathogens provides important information for the understanding and management of pathogen outbreaks in animal (non-human) and human populations.
Page Ref: 414-415
52) Describe the three fundamental features of cells of the innate immune system.
Answer: 1) Cells must recognize the presence of a threat, which requires the ability to distinguish cells from its own body (self) from other material (non-self).
2) Phagocytic cells search out and engulf foreign bodies, digesting them in lysosomes. These cells are also responsible for removing any debris in tissues that results from normal tissue breakdown.
3) Executioner cells target foreign cells, such as bacteria, or host cells that are infected with pathogens, and secrete cytotoxic compounds that either cause the cell to burst or trigger it to undergo apoptosis.
Page Ref: 418
53) Describe the process of B-cell activation.
Answer: B cells are produced in the bone marrow as stem cells, pass through a series of steps to become undifferentiated immature B cells, undergo genetic mutations, produce cell surface receptors encoded by Ig genes, and are then released from the bone marrow to circulate in the blood and lymph. Once they detect an antigen, they are activated, undergo a series of structural and genetic changes that depend on signals from other cells. Upon binding with an antigen on the APC (antigen-presenting cell), the final differentiated process is initiated. The activated B cells undergo monoclonal expansion, then hypermutation, and lastly differentiation. The hypermutation process results in binding antigens more efficiently. If the B cells don’t bind to an antigen, programmed cell death will occur. This programmed cell death ensures that any cells with detrimental mutations will be destroyed. Cells that bind effectively continue replicating and differentiating. Encounter with helper T cells stimulates final maturation. Some cells differentiate into plasma cells, which produce antibodies, while other cells remain as memory B cells. Memory B cells provide our immune system with the memory that leads to effective immunization.
Page Ref: 433, Fig. 10.16
54) Explain how immunization works and provide at least two examples of successful vaccination programs.
Answer: Memory B cells provide immunological memory, and this cell memory is the key to immunizations. When an animal is exposed to an inactivated antigen obtained from a potential pathogen, it does not cause disease symptoms, but the animal’s immune system produces memory cells. These memory cells respond very quickly upon detection of the pathogen’s antigens. A second exposure to the pathogen’s antigens results in quick reproduction of memory cells and rapid production of antibodies to fight the pathogen.
Examples of successful vaccination programs include 1) humans benefiting from the polio vaccine, 2) domestic pets being vaccinated against rabies, and 3) wildlife species being vaccinated when they ingest bait containing the rabies vaccine that is specifically dropped in areas where rabies is present (rabies eradication program).
Page Ref: 433-434
55) Describe how an allergic response occurs in respiratory and digestive systems in humans. What role do antihistamines play?
Answer: When an allergen comes into contact with the respiratory or digestive surface, the allergen/ antigen enters the tissue, binds IgE on mast cells in the mucosa, which results in a release of histamines. The cytokines released from the mast cells lead to an inflammatory response. In respiratory and digestive systems, the smooth muscle is affected, which results in mucus production and fluid imbalance. When a person’s digestive tract is affected, he/she suffers from diarrhea and vomiting. When the person’s respiratory tract is affected, he/she may suffer from asthma and bronchioconstriction.
Humans have numerous histamine receptors, such as H1, H2, H3, and H4.
Antihistamines block these receptors, thus decreasing the allergic response.
Page Ref: 435-436, Fig. 10.18
56) Discuss the relationship between steroid hormones, stress, and the immune system.
Answer: Everyone experiences stress at some time in his or her life, and stress can influence immune function. Immune systems can be negatively affected by specific hormones that “communicate” stress to the body. For example, under stress, glucocorticoids are produced at higher rates. High levels of glucocorticoids affect energy metabolism, decreasing nonessential energetic demands by decreasing protein synthesis. Higher steroid levels thus reduce the synthesis of proteins required for immune responses, such as pro-inflammatory cytokines. A study of marine iguanas found that dominant males in the hierarchy who were constantly defending their territories had high levels of corticosterone but weaker immune responses compared to males lower on the hierarchy with low levels of corticosterone, but stronger immune systems
Page Ref: 440
Chapter 11 Respiratory Systems
1) One of the immediate products of mitochondrial respiration is
A) oxygen.
B) ATP.
C) carbohydrate.
D) carbon monoxide.
Answer: B
Page Ref: 443
2) In the context of respiratory physiology, what is ventilation?
A) the process of moving the respiratory medium across the respiratory surface
B) the movement of air
C) the respiratory rate
D) cooling caused by panting
Answer: A
Page Ref: 444
3) Tidal ventilation is
A) when the ventilatory medium moves in and out of the respiratory chamber.
B) bulk flow of water across the respiratory surfaces of cnidarians.
C) the movement of water over the gills in most fish.
D) when the partial pressure of oxygen in the medium is variable in a diurnal rhythm.
Answer: A
Page Ref: 450
4) Which of the following factors is NOT required for high efficiency gas exchange?
A) moist surface
B) large surface area
C) low diffusion distance
D) high cell volume
Answer: D
Page Ref: 444-446
5) The primary purpose of a respiratory pigment is
A) oxygen transport.
B) oxygen and CO2 transport.
C) oxygen, CO2, and iron transport.
D) nutrient transport.
Answer: A Page Ref: 473
Copyright © 2016 Pearson Canada Inc.
6) Which of the following is NOT explicitly included in the Fick equation?
A) diffusion coefficient
B) area of the membrane
C) concentration gradient
D) temperature
Answer: D Page Ref: 445
7) Which of the following options is FALSE? The rate of diffusion is greatest when
A) the diffusion coefficient is small.
B) the membrane area is large.
C) the energy gradients are large.
D) the membrane is thin.
Answer: A Page Ref: 445
8) In terms of the ideal gas law, if the temperature increases and the volume is not fixed, then
A) pressure increases.
B) concentration decreases.
C) volume decreases.
D) gas constant increases.
Answer: B Page Ref: 445
9) In a spherical cell, the ratio of surface area to volume is
A) 1/r
B) 1/r2
C) π.
D) depends on cell size
Answer: A Page Ref: 448
10) The best way to explain cutaneous respiration is
A) diffusion of gases across a specialized respiratory surface with circulatory transport
B) circulating the external medium through the body
C) diffusion of gases across most or all of the body surface followed by transport of gases in an internal circulatory system
D) diffusion of gases across specialized internal and external membranes
Answer: C Page Ref: 449
11) Choose the most correct response. Which type of flow is most efficient?
A) concurrent
B) countercurrent
C) crosscurrent
D) It depends on the rate of flow of both the blood and the respiratory medium.
Answer: D Page Ref: 452
12) In crustacean respiration, ventilation happens when water moves out of the A) appendages.
B) branchial chamber.
C) scaphognathite.
D) carapace.
Answer: B Page Ref: 454
13) Sea cucumbers have internal respiratory sacs called
A) respiratory trees.
B) papulae.
C) peristomia.
D) lungs.
Answer: A Page Ref: 455
14) A lamprey is capable of
A) tidal ventilation.
B) unidirectional ventilation.
C) both A and B
D) neither A nor B
Answer: C Page Ref: 455
15) Blood flow through the gills of an elasmobranch is arranged in a __________ fashion.
A) countercurrent
B) concurrent
C) crosscurrent
D) convection
Answer: A Page Ref: 456
16) In a teleost fish, water enters the mouth when the A) operculum closes.
B) buccal cavity expands.
C) opercular cavity expands.
D) gills contract.
Answer: B Page Ref: 456, Figure 11.14
17) Ram ventilation is used by
A) feeding lampreys.
B) cnidarians.
C) swimming fish.
D) turtles.
Answer: C Page Ref: 458
18) Air enters the tracheae of insects through the A) spiracles.
B) ostia.
C) madreporite.
D) buccal cavity.
Answer: A Page Ref: 459
19) Which is the correct order of action for the amphibian "balanced breath"?
A) buccal cavity expands, glottis opens, spent air leaves lungs, buccal cavity contracts
B) buccal cavity expands, spent air leaves lungs, glottis opens, buccal cavity contracts
C) glottis opens, buccal cavity expands, buccal cavity contracts, spent air leaves lungs
D) spent air leaves lungs, glottis opens, buccal cavity expands, buccal cavity contracts
Answer: A Page Ref: 463
20) Generally, reptiles fill their lungs through
A) aspiration.
B) force of the buccal pump.
C) pressure changes during body movement.
D) passive air entry.
Answer: A Page Ref: 465
21) In birds, fresh air from the environment moves primarily into the A) lungs.
B) posterior air sacs.
C) anterior air sacs.
D) buccal cavity.
Answer: B Page Ref: 466
22) Bird lungs are efficient because of
A) their large size.
B) unidirectional and continuous air flow.
C) countercurrent blood flow.
D) capacity for discontinuous ventilation.
Answer: B Page Ref: 466
23) If lung compliance decreases, then
A) inhalation requires more energy.
B) inhalation requires less energy.
C) exhalation requires more energy.
D) exhalation requires less energy.
Answer: A Page Ref: 469
24) The shape of an alveolus is
A) round.
B) tubular.
C) polygonal.
D) elliptical.
Answer: C Page Ref: 470
25) Some of the air that enters the lung but does not participate in gas exchange is called the A) dead space.
B) void volume.
C) tidal waste.
D) residual volume.
Answer: A Page Ref: 470
26) The ideal ventilation perfusion ratio for the mammalian lung is A) 0.1.
B) 1.
C) 10.
D) 100.
Answer: B Page Ref: 472
27) Bronchoconstriction increases the work required to breathe because of
A) increased lung compliance.
B) decreased elastance.
C) increased airway resistance.
D) decreased intrapleural pressure.
Answer: C Page Ref: 470
28) Hemoglobins are
A) red.
B) blue.
C) clear.
D) green.
Answer: A Page Ref: 473
29) Hemoglobins get their color from
A) heme.
B) iron.
C) protein.
D) copper.
Answer: B Page Ref: 473
30) The oxygen equilibrium curve reaches a plateau when
A) the blood has reached its carrying capacity.
B) respiratory pigment molecules are depleted of oxygen.
C) iron levels are high.
D) the cycle of inhalation is complete.
Answer: A Page Ref: 476-477
31) Many vertebrates cope with hypoxia by
A) enlarging the spleen.
B) making more red blood cells.
C) using an alternate respiratory pigment.
D) decreasing hematocrit.
Answer: B Page Ref: 476
32) Many vertebrates’ response to hypoxia is contraction of which organ?
A) liver
B) pancreas
C) spleen
D) lung
Answer: C Page Ref: 476
33) Why do fetal mammals tend to have a lower hemoglobin P50 compared to adults?
A) This allows oxygen to be readily transferred from mother to fetus
B) This occurs because adults have a higher affinity for oxygen than the fetus
C) This applies only to species living in low-oxygen environments
D) Fetal mammals are smaller than adults
Answer: A Page Ref: 478
34) In most mammals, the effect of increased 2,3-DPG in the blood
A) increases the oxygen affinity of hemoglobin.
B) decreases the oxygen affinity of hemoglobin.
C) increases iron content of hemoglobin.
D) causes anemia.
Answer: B Page Ref: 482
35) How is an increased P50 of hemoglobin beneficial?
A) better oxygen unloading at the tissues
B) better oxygen loading at the lungs
C) better iron content of hemoglobin
D) better blood buffering capacity
Answer: A Page Ref: 482
36) Blood CO2 content is carried in the form of all of the following, EXCEPT
A) dissolved CO2.
B) bicarbonate.
C) carbaminohemoglobin.
D) carbonate.
Answer: D Page Ref: 482
37) In the blood, the carbonic anhydrase reaction yields
A) CO2.
B) H2O.
C) HCO3-
D) ATP.
Answer: C Page Ref: 482
38) In vertebrates, most of the bicarbonate in the blood is carried in the A) plasma.
B) red blood cell.
C) carbaminohemoglobin.
D) metabolon.
Answer: A Page Ref: 483
39) Bicarbonate enters and leaves the vertebrate red blood cell by A) diffusion.
B) bicarbonate pump.
C) bicarbonate channel.
D) chloride-bicarbonate exchanger.
Answer: D Page Ref: Figure 11.40
40) A Davenport diagram describes the relationship between all of the following factors, EXCEPT
A) CO2 concentration.
B) proton concentration.
C) bicarbonate concentration.
D) PCO2 .
Answer: A Page Ref: 485
41) When plasma CO2 increases, then
A) pH decreases.
B) HCO3- decreases.
C) CO increases.
D) H+ decreases.
Answer: A Page Ref: 485
42) Immediate regulation of blood pH can be adjusted by
A) changes in ventilation.
B) changes in excretion.
C) changes in hematocrit.
D) loss of consciousness.
Answer: A Page Ref: 485
43) In water-breathing vertebrates, the regulation of ventilation is sensitive to A) O2.
B) CO2
C) H+ .
D) salts.
Answer: A Page Ref: 487
44) Hypoxemia can be caused by all of the following EXCEPT
A) reduced activity level.
B) inadequate ventilation.
C) reduced blood hemoglobin content.
D) some disease states.
Answer: A Page Ref: 488
45) When an air-breathing animal experiences high-altitude hypoxia, restoring blood PO2 . through increased ventilation leads to all of the following EXCEPT
A) hypocapnia.
B) respiratory acidosis.
C) loss of drive to breathe.
D) low [H+].
Answer: B Page Ref: 489
46) Environmental hypoxia leads to the following pathological response:
A) vasoconstriction of pulmonary arterioles.
B) decreased ventilation rate.
C) decreased red blood cell numbers.
D) reduced tidal volume.
Answer: A Page Ref: 490
47) A vertebrate can store oxygen in a variety of places EXCEPT
A) blood.
B) muscle.
C) lungs.
D) hemocoel.
Answer: D Page Ref: 494
48) Why do many diving mammals allow their lungs to collapse during the dive?
A) The high pressure forces lung collapse.
B) It prevents water entry.
C) It prevents nitrogen narcosis.
D) The gas pressure in the lungs would damage alveoli.
Answer: C Page Ref: 495
49) If a fish swims forward with its mouth open, water will flow across the gills without active pumping. This is known as __________.
Answer: ram ventilation
Page Ref: 458
50) The subatmospheric pressure of the __________ prevents the mammalian lung from collapsing.
Answer: pleural sac
Page Ref: 467
51) Hemocyanins do not contain iron, but instead contain __________.
Answer: copper
Page Ref: 474
52) The equation for the ideal gas law is __________.
Answer: PV = nRT
Page Ref: 445
53) The __________ is the region of a solution that is in direct contact with the animal's body surface.
Answer: boundary layer
Page Ref: 448
54) Echinoderms suck water into the water vascular system via a sieved opening called the __________.
Answer: madreporite
Page Ref: 454
55) Most air-breathing chelicerates use a series of 10-100 thin lamellae, collectively called __________, to extract oxygen from the air.
Answer: book lungs
Page Ref: 459
56) In mammals, the trachea branches into two __________.
Answer: bronchi
Page Ref: 467
57) The site of gas exchange in mammals is at the blind-ended sacs called __________.
Answer: Alveoli; Page Ref: 467
58) The total volume of air moved in one ventilatory cycle is referred to as the __________.
Answer: tidal volume
Page Ref: 470
59) Cooperative binding produces an oxygen equilibrium curve with a _______________ shape.
Answer: sigmoidal
Page Ref: 478
60) Changes in pH and PCO2 alter the shape of the oxygen equilibrium curve for the respiratory pigments in many species, a phenomenon termed the __________.
Answer: Bohr effect
Page Ref: 479
61) The change in oxygen carrying capacity of the blood as the result of changes in pH is known as the __________.
Answer: Root effect
Page Ref: 479
62) When CO2 binds to hemoglobin, it forms __________.
Answer: carbaminohemoglobin
Page Ref: 479
63) The relationship between blood pH and CO2 can be described by the __________ equation.
Answer: Henderson-Hasselbalch
Page Ref: 483
64) The effect of oxygen on hemoglobin-carbon dioxide binding is known as the __________.
Answer: Haldane effect
Page Ref: 483
65) When alveolar ventilation is greater than is needed to remove the CO2 produced by metabolism, this is called __________.
Answer: hyperventilation
Page Ref: 485
66) When ventilation is greater than is needed to remove the CO2 produced by metabolism and pH increases in the blood, this is called __________.
Answer: respiratory alkalosis
Page Ref: 485
67) In at least some vertebrates, a small region of the caudal medulla called the __________ is essential for respiratory rhythm generation.
Answer: pre-Bötzinger complex
Page Ref: 486
68) The symptoms of nitrogen narcosis resemble symptoms of _________________.
Answer: alcohol ingestion
Page Ref: 494
69) Slowing the heart rate during a dive is called __________.
Answer: diving bradycardia
Page Ref: 495
70) In terms of pressure gradients, what is the difference between how frogs fill their lungs and how lizards fill their lungs?
Answer: An amphibian ventilates its lungs using a buccal force pump. In the first phase of ventilation, the frog expands its buccal cavity and draws air in through its open nares. Then, the glottis, which was closed, opens to allow the lungs to expel spent air into the buccal cavity and out the mouth and nares. The nares and mouth then close, the floor of the buccal cavity rises, and the fresh air in the buccal cavity is PUSHED into the lungs because the pressure in the buccal cavity is greater than the pressure in the lungs. The glottis then closes, which seals off the lungs and prevents air escape. This allows time for gas exchange. Lizards increase the volume of the chest cavity so that air is SUCKED into the lungs. During inspiration, the volume of the chest cavity increases through the contraction of intercostal muscles (snakes and lizards), sheetlike abdominal muscles (turtles and tortoises), or diaphragmaticus muscles (crocodilians). The increase in chest volume decreases lung pressure, which causes air to enter the lungs. During expiration, the volume of the chest cavity decreases, increasing the pressure and causing air to exit.
Page Ref: 463-465
71) When Fick's equation is combined with Henry's and Graham's laws, an equation can be derived that describes the rate of diffusion of a gas through a fluid at constant temperature. In table format, list the factors that will influence diffusion rate and state how increasing the value of each factor will affect the diffusion rate.
Answer: The equation is given as: diffusion rate α *D A ΔPgas Sgas] / [X ✓MW]
Diffusion coefficient (D)
Cross-sectional area (A)
Partial pressure gradient (ΔPgas)
Solubility of the gas in the fluid (Sgas)
Diffusion distance (X)
Molecular weight (MW)
Page Ref: 446
Increase diffusion rate
Increase diffusion rate
Increase diffusion rate
Increase diffusion rate
Decrease diffusion rate
Decrease diffusion rate
72) Discuss three limitations to the strategy of cutaneous respiration.
Answer: A variety of animals, including aquatic invertebrates, terrestrial annelid worms, and some vertebrates such as frogs and salamanders, use cutaneous respiration as a strategy for gas exchange. Even bird eggs use this strategy, since all gas exchange with the environment must occur across the eggshell. There are, however, some limitations to this respiratory strategy. First, the animal must have very thin skin to reduce the diffusion distance between the environment and the circulating fluid. The thin skin leaves the animal vulnerable to predation and physical damage. Secondly, the skin must remain moist so that dissolved oxygen can diffuse into the cell. The requirement for moist skin confines animals to aquatic or very moist terrestrial habitats. Finally, because of the first two constraints, the surface area of the skin is limited, which ultimately limits its respiratory capacity.
Page Ref: 449
73) Describe four ways in which vertebrate gills and lungs are similar.
Answer: The purpose of both gills and lungs is to provide a place for gas exchange. Many of the factors listed here can be elucidated from the equation for diffusion rate given on page 415. For example, gills and lungs are similar in that they both provide a thin barrier in order to reduce the diffusion distance. They have a high surface area to supply more physical space for diffusion. They must remain moist so that respiratory gases can dissolve. Both types of respiratory surface are ventilated to reduce the development of a boundary layer. Also, for both lungs and gills, a circulatory system allows oxygen from the respiratory surface to be transported across long distances by bulk flow.
Page Ref: 446, 450
74) Why do "water breathers" have a lower blood PCO2 than air breathers?
Answer: The oxygen content of air is almost 30 times that of water at 20°C. In order to obtain sufficient oxygen, water breathers must ventilate the respiratory surface nearly 30 times more vigorously to move the same amount of oxygen across the respiratory surface as air breathers do. However, this rate is more than is necessary to adequately eliminate produced CO2 from the blood. Because of this, water breathers have a low blood PCO2 In contrast, air breathers do not need to ventilate at such a high rate to obtain oxygen, because the oxygen content of air is so high. Consequently, due to a reduced ventilation rate, they do not eliminate CO2 as rapidly. This results in higher blood PCO2 levels.
Page Ref: 453
75) What is ram ventilation? Is ram ventilation energetically "free"? Justify your answer.
Answer: Teleost fish use a buccal-opercular pump to ventilate the gills. Water flows from the mouth through the buccal cavity and into the opercular cavity, and then out through the slit formed by the operculum. However, if a fish swims forward with its mouth open, water will flow across the gills without active pumping by the muscles surrounding the buccal and opercular cavities. This strategy is called ram ventilation, and is used by many active fish species. Ram ventilation is efficient because the fish does not need to use the muscles around its buccal and opercular cavities to move water through the gills. However, the fish needs to be swimming, which is energetically costly, and its body position with the mouth open may increase drag on the fish and increase the cost of locomotion. Therefore, the answer can be either yes or no, depending on how it is justified.
Page Ref: 458
76) Describe the strategies that some aquatic insects, such as mosquito larvae and dipteran larvae, use to breathe air. What is the limitation of these strategies?
Answer: Mosquito larvae breathe air through specialized structures that act as siphons. The mosquito larvae must stay close to the water’s surface with their siphons, which must protrude above the surface of the water for the larvae to breathe air. Dipteran larvae utilize a slightly different strategy; they have a pointed abdominal siphon, which they use to puncture the surface of aquatic plants and obtain oxygen that is produced by photosynthesis. The limitation for both these insect larvae is that they cannot venture far from an air source.
Page Ref: 460-461
77) Describe the three phases of discontinuous ventilation in insects and give two possible reasons for its adaptive significance.
Answer: a. Insects use a tracheal system for gas exchange. Air enters the tracheae (passively or through active ventilation) through spiracles that have the capacity to open and close. The air travels down the tracheae to tracheoles, and then oxygen diffuses into the tissues.
b. Discontinuous ventilation is a ventilatory pattern that is sometimes used by insects when they are at rest. Discontinuous ventilation has three phases. In the first phase (the closed phase), the spiracles remain shut to prevent gas exchange with the environment. This causes the PO2 in the tracheoles to drop, since the body is still consuming oxygen. The carbon dioxide produced by metabolism reacts with water in the interstitial fluid to form bicarbonate, and therefore the PCO2 in the tracheoles does not increase much. The decline in O2 without an increase in CO2 causes a slight decrease in the total gas pressure within the trachea. In the second phase (flutter phase) the spiracles open and close many times rapidly. The low gas pressure within the tracheae causes air to enter the tracheae during this time. Over time, CO2 will accumulate when it can no longer be stored as bicarbonate, and PCO2 will increase in the tracheae. At this point, the third phase occurs, when the spiracles open completely and CO2 is released.
There are three hypotheses listed in the textbook regarding the adaptive significance of discontinuous ventilation:
i. It may facilitate tracheal ventilation: By generating a low PO2 within the tracheae, it creates a greater PO2 gradient between the tracheae and the environment. When the spiracles finally open, the oxygen will diffuse more readily into the tracheae. This could be particularly useful for insects that spend large portions of time in places where environmental PO2 is low and PCO2 is high (e.g., underground).
ii. It may help to minimize water loss across the tracheae by having the spiracles closed for longer periods of time.
iii. It may protect insects from the harmful effects of oxygen. Although oxygen is necessary for most animal life, it is also a highly reactive chemical that can damage tissues. When an insect's spiracles are fully open, fresh air can diffuse deep into the tissue, and the PO2. at the ends of the tracheoles is much higher than the PO2. that vertebrate tissues would experience. This exposure could result in tissue damage. During discontinuous ventilation, the PO2. would only be high intermittently. Page Ref: 462
78) What is lung compliance? How is it that surfactants increase lung compliance?
Answer: The ability of the lungs to reversibly change shape can be quantified using two parameters. One of these parameters is compliance, which is a measure of how easy it is to stretch the lung (during inhalation). The other measure is elastance, which is a measure of how readily the lung returns to its original shape (during exhalation). A highly compliant lung stretches more in response to a pressure change than does a less compliant lung. Compliance is a function of the change in lung volume divided by the change in transpulmonary pressure (ΔV/ΔP). Therefore, for a highly compliant lung, generating the same transpulmonary pressure upon inhalation will result in greater filling of the lung, which is desirable. A force that resists lung inflation (and thus reduces compliance) is surface tension of the thin layer of liquid that exists in the small airways and alveoli. Surface tension is generated mostly through hydrogen bonding, and causes two wet surfaces to stick together. This is detrimental to lung filling. For example, in premature human babies, surfactants are not present in the lungs in sufficient amounts to contribute to lung compliance, which makes breathing difficult. Surfactants, however, such as lipoprotein surfactants, reduce the surface tension of the fluid layer lining the lungs by disrupting the hydrogen bonds, increasing lung compliance and permitting lung inflation.
Page Ref: 469 and 470
79) Draw and explain the sigmoidal shape of the oxygen equilibrium curve for vertebrate hemoglobin. In your drawing, be sure to label your axes.
Answer: Monomeric respiratory pigments, such as mammalian myoglobin, have a hyperbolic oxygen equilibrium curve because they do not bind oxygen cooperatively. Hemoglobins, on the other hand, are multimeric respiratory pigments. They display cooperative binding, which means that its affinity for oxygen changes with the amount of oxygen already bound. Hemoglobins are composed of two α and two β subunits that form two dimers that interact loosely with one another. When a hemoglobin molecule is fully deoxygenated, it is in the rigid T state. It is stabilized by hydrogen bonds, binding of allosteric effectors, and salt bridges between the subunits. In this state, it has a relatively low affinity for oxygen. But when oxygen binds to one of the heme groups, the hemoglobin changes to an R state, with an increased affinity for oxygen. The net effect of this cooperative binding is an oxygen equilibrium curve with a sigmoidal shape. The oxygen equilibrium curve should be drawn with PO2 on the x-axis, and percent saturation of hemoglobin on the y-axis.
Page Ref: 478-479
80) Which receptors trigger the Hering-Breuer inflation reflex, and why is this reflex important?
Answer: The Hering-Breuer inflation reflex is triggered by a set of mechanoreceptors, the slowly adaptive pulmonary stretch receptors. These detect the amount of tension in the walls of the airways, including the trachea and bronchi. This reflex is thought to protect the lungs from being damaged by overinflation by terminating inhalation.
Page Ref: 488
81) Why do birds tend to show greater tolerance to high-altitude hypoxia than do mammals? Using the bar-headed goose as an example, list three evolutionary adaptations that enable this species to successfully migrate at high altitudes, such as over the Himalayas at over 9000 m.
Answer: Hypoxia is a condition where the body is deprived of adequate oxygen. The lung anatomy of birds differs from mammals and is advantageous at high altitudes. In birds, unidirectional ventilation, a thin gas exchange surface, and cross-current flow result in very efficient gas exchange and oxygen extraction. Birds have higher capillary density and smaller muscle fibers compared to mammals, which results in better gas exchange at the muscles. Furthermore, birds tolerate hyperventilation better than mammals, so they obtain more oxygen at high altitudes.
When we compare lowland birds with bar-headed geese we observe three striking differences. Bar-headed geese have larger lungs for their body size, so the greater surface area provides higher oxygen diffusion capacity. Barheaded geese also have hearts with a higher density of capillaries, which improves oxygen delivery to their hearts. Mitochondria in muscle cells of barheaded geese is found much closer to capillaries, thus reducing the distance between mitochondria and blood, and resulting in a higher diffusion capacity for oxygen.
Page Ref: 490 and Box 11.3 on p. 492
Chapter 12 Locomotion
1) Hummingbirds can hover because
A) they have large breast muscles that enable their wings to generate lift in the upstroke and downstroke
B) they burn only sugar and not fat
C) their wings beat rapidly, often higher than 30 beats/sec
D) A and C
Answer: D
Page Ref: 499
2) Invertebrate locomotor muscles are typically
A) striated.
B) smooth.
C) discontinuous.
D) pseudostriated.
Answer: A
Page Ref: 500
3) In what way(s) are the muscle arrangements in the body wall of earthworms similar to those of the human digestive tract?
A) Both exhibit peristaltic waves of contractions.
B) Both are organized into layers of circular and transverse muscles
C) Both consist of striated muscle.
D) all of the above
Answer: A
Page Ref: 500
4) What is the function of setae of the integument of earthworms?
A) They serve as chemosensory structures.
B) They serve as proprioceptors.
C) They provide anchorage during burrowing.
D) all of the above
Answer: C
Page Ref: 501, Fig. 12.4
5) The locomotor muscles of fish tend to have which of the following characteristics?
A) Of the two muscle fiber types, in terms of mass, the majority is red muscle.
B) The white muscle is glycolytic and is responsible for brief, high-speed swimming.
C) White muscle is usually restricted to a ribbon that underlies the lateral line.
D) White muscle is oxidative and supports slow, steady-state cruising.
Answer: B
Page Ref: 502
6) Which of the following statements is correct regarding the red and white locomotor muscles of fish?
A) White muscle exhibits maximal power output at lower tail-beat frequencies.
B) Fish tend to use red muscle for slow, often continuous swimming.
C) Red muscle tends to be more glycolytic.
D) Red muscle shows maximal power output at high tail-beat frequencies.
Answer: B
Page Ref: 502
7) Much of our understanding of the tetrapod muscle function is derived from studies of the
A) muscles comprising the walls of the squid mantle cavity.
B) diaphragm of the white laboratory rat.
C) external oblique muscles of Necturus and other non-jumping amphibians.
D) muscles comprising the hindlimb of frogs.
Answer: D Page Ref: 504
8) Of the muscles employed by the mammalian hindlimb during walking, the __________ works in concert with others to flex the limb.
A) tibialis anterior
B) gastrocnemius
C) soleus
D) rectus femoris
Answer: A Page Ref: 505
9) Which muscle powers the downstroke in bird flight?
A) brachioradialis
B) triceps
C) pectoralis
D) supracoracoideus
Answer: C Page Ref: 506
10) During muscle activity, ATP plays a role in providing energy for
A) cross-bridge cycling.
B) establishing ion gradients across the sarcolemmal membrane.
C) transporting Ca2+ back to the sarcoplasmic reticulum.
D) all of the above
Answer: D Page Ref: 506
11) All but which one of the following compounds is an invertebrate phosphogen?
A) phosphoarginine
B) phosphocreatine
C) phosphoglycocyamine
D) phospholambricine
Answer: B
Page Ref: 507
12) __________ is the substrate used by both the mitochondria and in glycolysis to generate ATP.
A) Carbohydrate
B) Fatty acids
C) Amino acids
D) all of the above
Answer: A Page Ref: 508
13) Muscles possess low levels of __________ that can be oxidized immediately.
A) glucose
B) fatty acids and glycerol
C) free amino acids
D) all of the above
Answer: D Page Ref: 508
14) The highest concentration of mitochondria per unit volume can be found in
A) the glycolytic muscle fibers in the leg of an Olympic sprinter.
B) the flight muscles of insects and hummingbirds.
C) the glycolytic muscle fibers in the white breast meat of a chicken.
D) the glycolytic muscle fibers in the back of a weight lifter.
Answer: B Page Ref: 508
15) An important step in the recovery process of skeletal muscle is the removal of __________ that accumulates from the result of anaerobic glycolysis.
A) acetate
B) lactate
C) pyruvate
D) urea
Answer: B Page Ref: 508
16) One of the features of the Cori cycle is the
A) conversion of muscle-derived lactate into glucose by the liver.
B) oxidation of lactate by the heart.
C) conversion of lactate into glycogen by the muscle fibers.
D) all of the above
Answer: A Page Ref: 508
17) During the latter stages of long-distance reproductive migrations, salmon resort to___________ as an energy source.
A) Lipid stores
B) ingested food
C) endogenous proteins
D) nucleic acids
Answer: C
Page Ref: 514-515 Box 12.2
18) In adipose tissue, hormone-sensitive lipase
A) is controlled by corticotropin, epinephrine, and glucagon.
B) is activated via the IP3 pathway of signal transduction.
C) regulates the docking of LDL and other lipoproteins.
D) all of the above
Answer: A
Page Ref: 510
19) All but one of the statements correctly describes T2DM; which one is it?
A) T2DM is a metabolic disorder, likely linked to the current lifestyle of humans being at odds with the evolution of our physiology
B) In T2DM, more glucose is taken up by adipose tissue and converted to fat
C) In T2DM, tissues become unresponsive to insulin.
D) In T2DM, insulin is produced by the liver in response to higher glucose levels in the blood
Answer: D
Page Ref: 510, 512 (Applications 12.1)
20) Oxygen diffusion distances are greater in glycolytic muscles because glycolytic muscles
__________ than aerobic muscles.
A) are smaller
B) have fewer capillaries
C) have higher oxygen demands
D) all of the above
Answer: B
Page Ref: 512
21) The regular cycling between constriction and dilation of arterioles feeding capillaries is known as
A) vasocongestion.
B) vasodilation.
C) vasomotion.
D) vasospasm.
Answer: C
Page Ref: 512
22) Whales and seals prepare for a dive by
A) storing excess blood in the liver for later use.
B) sequestering high levels of intracellular calcium to buffer pH changes.
C) saturating myoglobin stores with oxygen.
D) all of the above
Answer: C Page Ref: 513
23) From an evolutionary perspective, animals produce myoglobin
A) to reduce the costs of building and maintaining vasculature.
B) to increase intracellular storage of CO2 and reduce dependence on carbonic anhydrase.
C) to mediate the detrimental effects of pH changes by serving as an intracellular buffer.
D) to serve as an intracellular sink of amino acids.
Answer: A Page Ref: 513
24) The exoskeleton of insects is composed of a variety of materials including the carbohydrate
A) cellulose.
B) chitin.
C) dextran.
D) sclerotin.
Answer: B Page Ref: 516
25) In insects, indirect flight muscles
A) tend to be found in the more primitive orders such as the locusts and dragonflies.
B) change the position of the wings by altering the shape of the thorax.
C) function in the absence of direct flight muscles.
D) are also referred to as synchronous flight muscles.
Answer: B Page Ref: 516
26) Cartilaginous skeletons are found in
A) lampreys.
B) hagfish.
C) sharks and rays.
D) all of the above
Answer: D Page Ref: 516
27) In terms of joint anatomy, bones are held to other bones by A) bursae.
B) cartilage.
C) ligaments.
D) tendons.
Answer: C Page Ref: 517
28) During the process of bone formation,
A) osteoclasts secrete collagen fibers.
B) collagen fibers help organize the deposition of calcium phosphate apatite.
C) osteoblasts secrete hydrolytic enzymes creating tunnels into the bone or cartilage.
D) osteocytes ultimately mature into inactive osteoclasts.
Answer: B
Page Ref: 517
29) The arrangement of most muscles and bones in animal locomotion fall into the category of class __________ levers.
A) I
B) II
C) III
D) IV
Answer: C Page Ref: 518
30) In most animals, the organization of muscles and bones of locomotion into a system of levers
A) confers significant mechanical advantage.
B) increases the range and velocity of movement.
C) is functionally analogous to a wheelbarrow-type lever.
D) is functionally analogous to a crowbar-type lever.
Answer: B Page Ref: 518
31) The role of extensor muscles, absent in the leg joints of many spiders, has been replaced by
A) fluid movements and pressure changes of the hydrostatic skeleton.
B) strategically placed exoskeletal plates that store elastic energy when deformed.
C) a system of chitinous self-locking and unlocking catches and levers.
D) a system of autonomously controlled valves within the legs.
Answer: B
Page Ref: 519-520
32) Given two muscles of equal mass, a short, thick muscle and a long, thin muscle, one would expect the short, thick muscle to
A) contract with a greater force.
B) have its sarcomeres arranged in series rather than parallel.
C) shorten faster and further, but generate less force.
D) all of the above
Answer: A Page Ref: 519
33) Compared to other fish, the capacity for oxidative phosphorylation is significantly greater in the tuna due to the
A) homogeneous distribution of thick-fibered red muscle.
B) higher mitochondrial content of the red muscle fibers.
C) more extensive branching of the T-tubules.
D) denser packing of cristae in the mitochondria of the red muscles.
Answer: D Page Ref: 513
34) The most important parameter in most forms of locomotion is
A) force.
B) leverage.
C) mechanical power.
D) stroke volume.
Answer: C Page Ref: delete, not applicable to 3e
35) __________ is the element of the physical environment that has the greatest consequences for locomotor strategies.
A) Gravity
B) Viscosity
C) Resistance
D) Turbulence
Answer: A Page Ref: 522
36) Which of the following biomaterials has the highest specific gravity?
A) cartilage
B) protein
C) triglyceride
D) squalene
Answer: A Page Ref: 522
37) Many species of zooplankton possess large droplets of lipid, typically in the form of __________, to increase their buoyancy.
A) cholesterol
B) squalene
C) triglycerides
D) wax esters
Answer: D Page Ref: 522
38) Sharks and rays increase their buoyancy by accumulating __________ in their livers.
A) cholesterol
B) squalene
C) triglycerides
D) wax esters
Answer: B Page Ref: 522
39) The viscous effects of water would have the greatest impact on inhibiting the forward motion of a
A) copepod.
B) minnow.
C) tuna.
D) whale.
Answer: A Page Ref: 525
40) Which of the following organisms would have the largest Reynolds number?
A) copepod
B) minnow
C) tuna
D) whale Answer: D Page Ref: 525
41) The curved upper surface of an aerofoil of the wing of an airplane or a bird is critical in generating
A) drag.
B) lift.
C) angular momentum.
D) thrust. Answer: B Page Ref: 527
42) True flight has arisen in
A) birds and reptiles.
B) mammals.
C) insects.
D) all of the above Answer: D Page Ref: 528
43) True flight first arose in
A) bats.
B) birds.
C) insects.
D) reptiles. Answer: C Page Ref: 528
44) The fine muscles within the wings of __________ allow for substantial changes in the wing shape.
A) bats
B) birds
C) insects
D) all of the above Answer: A Page Ref: 530
45) Tuna and the fastest sharks (such as the mako) have __________ caudal fins.
A) homocercal
B) holocercal
C) heterocercal
D) mesocercal
Answer: A Page Ref: 531
46) The costs of locomotion for animals moving at their optimal velocities are
A) lowest for swimmers.
B) highest for fliers.
C) lowest for runners.
D) highest for swimmers.
Answer: A Page Ref: 537
47) For most swimming animals, drag is proportional to the A) square root of the buoyancy.
B) inverse of the mass-specific metabolic rate.
C) Reynolds number.
D) velocity squared.
Answer: D Page Ref: 538
48) Among animals in the following list, the phenomenon of drag has the most pronounced effect on the locomotion of a
A) kangaroo.
B) bat.
C) sparrow.
D) trout.
Answer: D Page Ref: 539
49) What is the single-most important determinant of the efficiency of locomotion among all animals?
A) surface area
B) shape
C) body size
D) frictional drag
Answer: C Page Ref: 538
50) The preferred form of stored fuel for migratory animals is
A) amino acids.
B) glycogen and other types of starch.
C) lipid.
D) protein.
Answer: C Page Ref: 514Box 12.2
51) As a general rule, in temperate regions the most important environmental cue that triggers migration is
A) photoperiod.
B) temperature change.
C) change in food quality and abundance.
D) all of the above
Answer: A
Page Ref: 514 Box 12.2
52) Migratory excursions can be distinguished from other types of animal movements by
A) being relatively persistent and of long duration.
B) being primarily linear in direction.
C) the animals being unresponsive to normally distracting stimuli.
D) all of the above
Answer: D
Page Ref: 514
53) Which of the following statements is correct?
A) Small mammals are more constrained by evolutionary history than large mammals.
B) In vertebrates, connective tissue and bones are the most important elastic energy stores.
C) Collagen of small mammals has very different properties than collagen of large mammals.
D) Smaller animals store more elastic energy during movement than larger animals.
Answer: B
Page Ref: 540
54) A fluid-filled internal chamber that supports the body of an animal is known as a
Answer: hydrostatic skeleton
Page Ref: 500
55) Earthworms organize locomotor striated muscles into __________ and __________ layers.
Answer: circular; longitudinal Page Ref: 500
56) During peristaltic burrowing in earthworms, when the __________ muscles contract, the segment extends or lengthens.
Answer: circular Page Ref: 501
57) The white muscles of fish are organized into units of parallel layers derived from internal segments of the embryo called __________.
Answer: myotomes
Page Ref: 502
58) In fish, the pattern of the sequential activation of muscle contraction is known as __________ and is under the control of the central nervous system.
Answer: recruitment
Page Ref: 503
59) Limb musculature of tetrapods is developmentally _____________ to fin musculature of fish.
Answer: homologous
Page Ref: 504
60) The movement of a limb bending at a joint is called flexion, and straightening is called __________.
Answer: extension
Page Ref: 505
61) Limb muscles tend to be organized into __________ pairs like triceps and biceps such that they are responsible for opposing movements.
Answer: antagonistic
Page Ref: 505
62) All the muscles that are responsible for a type of movement, like those employed in bipedal walking, are grouped together into a __________.
Answer: locomotor module
Page Ref: 505
63) In the absence of oxygen, the only option for skeletal muscles to generate ATP is __________.
Answer: glycolysis
Page Ref: 507
64) An important step in the recovery process of skeletal muscle is the removal of __________ that accumulates from the result of anaerobic glycolysis.
Answer: lactate
Page Ref: 508
65) Animals often show elevated rates of oxygen consumption long after the cessation of exercise, a phenomenon called __________.
Answer: oxygen debt
Page Ref: 508
66) A hummingbird becomes ______________ when it relies on its energy reserves and drops its body temperature to conserve energy.
Answer: hypometabolic
Page Ref: 509
67) The __________ distance is the effective diffusion distance for oxygen from the capillary into the surrounding tissue.
Answer: Krogh
Page Ref: 512
68) Once oxygen leaves the capillary and crosses the muscle cell plasma membrane, it is rapidly bound by __________.
Answer: myoglobin
Page Ref: 513
69) __________ fish inflate their swim bladders indirectly via a vascularized region of the bladder called the gas gland.
Answer: Physoclist
Page Ref: 523
70) The __________ number is a mathematical expression that describes the relationship between turbulent and laminar flow as a function of the properties of fluids, objects, and movement.
Answer: Reynolds Page Ref: 524
71) The forces that oppose the forward movement of an object through a liquid are collectively referred to as __________.
Answer: drag Page Ref: 525
72) The cross-sectional view of the wings of birds and planes reveals a curved upper surface demonstrating both to be __________.
Answer: aerofoils
Page Ref: 527
73) In all sharks, the rigid __________ fins generate lift and prevent rolling.
Answer: pectoral
Page Ref: 531
74) The __________ caudal fins of cruising sharks are much taller on the dorsal side than on the ventral side.
Answer: heterocercal
Page Ref: 531
75) The vertical midpoint in the mass of an animal is called its __________.
Answer: center of gravity
Page Ref: 533
76) Describe the organization of the muscles of the mantle of a squid and the mechanism of jet propulsion.
Answer: The muscles of the outer body wall are intermingled in two planes: radial muscle fibers extend from the inside to the outside and three layers of circular muscles comprise the circumference. When the muscles relax, the volume of the mantle cavity increases and water enters. Contraction of the muscles decreases the volume of the cavity and water is forced out through the siphon generating jet propulsion.
Page Ref: 501-502
77) Describe the organization of the locomotor white muscles of fish as well as the direction of the contractile forces.
Answer: The white muscle fibers are organized into embryologically derived myotomes separated by thin layers of connective tissue called myopsepta. Tendons connect each myotome to the posterior; the skin acts as a sheath to connect the different myotomes. During contraction, force is transmitted from one myotome to the next across myosepta to the caudal fin along the tendons and to the skin.
Page Ref: 502-503
78) Briefly name and explain the roles of the various hindlimb muscles that function in walking in mammals.
Answer: The leg is moved forward by the extensor group of muscles including the soleus and gastrocnemius for bending the foot, the quadriceps and rectus femoris for straightening the knee, and the gluteus for swinging the leg forward. The flexor group provides the antagonistic movements and include the tibialis anterior for moving the foot, the hamstring group for bending the knee, and the iliopsoas for rotating the leg at the hip.
Page Ref: 505
79) How does the mitochondrial content vary among muscle types and species?
Answer: The mitochondrial content of glycolytic muscle is sparse, typically comprising less than two percent of the intracellular space, whereas the levels are usually 3- to 10-fold higher in the oxidative muscle fibers of the same animal. Highest concentrations of mitochondria are found in the flight muscles of insects and hummingbirds with almost half of the intracellular volume occupied by mitochondria.
Page Ref: 507-508
80) What is the relationship between glucose and triglycerides as skeletal muscle energy substrates as a function of activity level?
Answer: During low to moderate activity, glucose remains the more important metabolic fuel, with glycogen breakdown being stimulated in both the liver and muscle. With sustained activity, glycogen stores become depleted and triglycerides from skeletal muscle and adipose tissue are mobilized to an increasing extent.
Page Ref: 509-510
81) Describe the relationship between activity/diet and type 2 diabetes mellitus (T2DM).
Answer: Until recently, humans evolved on a high-exercise regime as hunters and gatherers, and their diet consisted of natural and unprocessed foods. At the present time, our lack of activity and a diet of unlimited processed food have drastically diverged with what our physiology has evolved to do. Our current “unnatural” lifestyle (lack of exercise and overeating of unhealthy foods) manifests itself in many metabolic disorders. One of the most widespread and rapidly growing metabolic disorders is T2DM. In T2DM, tissues fail to respond to insulin. In healthy individuals, an increase in blood glucose levels (for example, after a meal) initiates the production of insulin. Under normal conditions, insulin improves glucose uptake via glut-4 transporters in tissues such as skeletal muscle (a key glucose-consuming tissue). Skeletal muscles of individuals with T2DM are insensitive to insulin, so the glucose is taken up by
the liver and adipose tissue and converted to fat. All the extra fat is associated with obesity, cardiovascular disease, and hypertension. Furthermore, as a result of the insensitivity of tissues to insulin, beta cells of the pancreas keep on synthesizing insulin, and after a while the beta cells fail to function. The problem with T2DM is twofold; it may lead to obesity, but obesity can also lead to T2DM.
Page Ref: 510-511, 512 (Applications 12.1)
82) Explain the mechanism by which oxygen perfusion is increased in hypoxic muscle tissue.
Answer: When endothelial cells experience hypoxia, levels of hypoxia-inducible factor increase and trigger the release of the hormone vascular endothelial growth factor into the walls of the blood vessels, binding specific receptors. The response is cell proliferation and the ultimate growth of blood vessels into hypoxic tissues, thereby increasing the rates of perfusion.
Page Ref: 512-513
83) Describe the process of bone growth.
Answer: Bone is a collection of multiple cells, cellular secretions, and mineral salts, collectively enveloped by the periosteum, and constantly undergoing remodeling. Osteoclasts secrete hydrolytic enzymes that generate tunnels to allow for penetration by blood vessels and invading osteoblasts. Osteoblasts secrete collagen fibers that serve as the framework for the deposition of calcium phosphate apatite.
Page Ref: 517
84) How does the caudal fin of a fish generate thrust?
Answer: Movement of the caudal fin through the water creates circular patterns of water movement called vortices that represent the transfer of force from the fish to the environment. As the fish swims through the water, a series of interlinked vortices form in its wake and it is these fluid movements that provide the force that propels the fish forward.
Page Ref: 530-531
85) Discuss the relationship between wing size and body mass in birds.
Answer: A combination of wing span and wing surface area influences lift. Among birds within the same order and sharing similar lifestyles (e.g., soaring long distances over open ocean), analysis by scaling to the same wing span reveals the significance of wing shape: Larger birds have proportionately longer and narrower wings.
Page Ref: 530-531
86) Discuss long-distance migration of sockeye salmon and ruby-throated hummingbirds with respect to stimulus for migration, metabolic preparation, feeding during migration, and metabolism during migration.
Answer: Sockeye salmon grow and mature in the ocean and their migration to freshwater streams/rivers, where they were born, is seasonal and stimulated by reproductive maturity. To prepare for migration, the salmon fatten up and store most of the energy needed for migration as lipid or fat. Salmon do not feed during migration; they rely totally on their energy reserves. The advantage of not feeding on route means salmon do not need to utilize any
time searching for food and avoid the risk of predation while feeding. Ruby-throated hummingbird’s migration south to wintering grounds is stimulated by photoperiod. Hummingbirds, like many migrating animals, store fat for migration because fat has a high energetic density. Unlike sockeye salmon, hummingbirds require more energy for migration than they can store, and as a result, they need to feed along their migration route.
Page Ref: 514, 516 (Box 12.2)
Chapter 13 Ion and Water Balance
1) How do iguanas maintain water and ion balance?
A) Marine iguanas produce urine that contains a higher ion concentration than blood.
B) A specialized salt gland in their nose produces a highly concentrated salt solution that is expelled.
C) Marine iguanas use their kidneys to excrete excess salt.
D) Marine iguanas need to drink fresh water on land to maintain the optimal water and ion balance.
Answer: B Page Ref: 543
2) Most animals rely on tissues such as the gills, skin, and kidney to regulate three homeostatic processes. Which of the following is NOT one of those processes?
A) osmotic regulation
B) ionic regulation
C) nitrogen excretion
D) endocrine balance
Answer: D Page Ref: 543
3) Ammonia is the end product of __________ catabolism.
A) protein
B) carbohydrate
C) lipid
D) nitrogen
Answer: A Page Ref: 543
4) Osmosis is
A) the energetically favorable movement of water across a semipermeable membrane, from an area with a high activity of water to an area with low activity of water.
B) the energetically costly movement of water across a semipermeable membrane, from an area with a high activity of water to an area with low activity of water.
C) the energetically favorable movement of solute across a semipermeable membrane from an area with a low activity of water to an area with high activity of water.
D) the energetically favorable movement of water across a semipermeable membrane
from an area with a low activity of water to an area with high activity of water.
Answer: A Page Ref: 543
Copyright © 2016 Pearson Canada Inc.
5) All animals require water, and it may be provided in many forms. Which of the following is NEVER a source of water for an animal?
A) seawater
B) dietary water
C) products of hydrolysis
D) products of oxidative phosphorylation
Answer: C Page Ref: 546
6) Where do humans obtain most of their water?
A) drinking water
B) water trapped in solid food
C) metabolic water
D) condensation reactions
Answer: A Page Ref: 547
7) Perturbing solutes include all of the following EXCEPT
A) Na+
B) K+
C) charged amino acids.
D) trehalose.
Answer: D Page Ref: 547
8) Compatible solutes
A) disrupt macromolecular function.
B) do not disrupt macromolecular function, as long as the concentration is low.
C) do not disrupt macromolecular function, even at high concentration.
D) do not disrupt macromolecular function, as long as there are counteracting solutes present.
Answer: C Page Ref: 547
9) The cytoplasm of most animals is dominated by the same ions. Which of the following is NOT one of those ions?
A) K+
B) Cl-
C) Na+
D) SO4-
Answer: C Page Ref: 548
10) Which of the following features of the stratum corneum is incorrect?
A) It is composed of differentiated epithelial cells.
B) Its purpose is to reduce water loss.
C) The tissue is dead and unresponsive to physical changes.
D) It is heavily keratinized.
Answer: C Page Ref: 551-552
11) The main component of insect chitin is
A) polysaccharide.
B) protein.
C) lipid.
D) nucleic acid.
Answer: A Page Ref: 552
12) The toxic by-products of amino acid breakdown must be excreted. Which of the following is NOT one of the main forms of nitrogen excretion?
A) ammonia
B) pyridine
C) urea
D) uric acid
Answer: B Page Ref: 555
13) Which compound has the lowest molecular weight?
A) ammonia
B) urea
C) uric acid
D) protein
Answer: A Page Ref: 555
14) Which animal group is NOT considered ammoniotelic?
A) mammals
B) agnathans
C) aquatic mollusks
D) chondrichthians
Answer: A Page Ref: 555 Table 13.3
15) The most immediate product of xanthine oxidation is
A) uric acid.
B) urea.
C) glutamine.
D) adenosine.
Answer: A Page Ref: 557
16) The ornithine-urea cycle happens in which two locations?
A) nucleus, endoplasmic reticulum
B) mitochondrion, cytoplasm
C) cytoplasm, intercellular space
D) ribosome, cytoplasm
Answer: B Page Ref: 557
17) Urea is made in the
A) kidney.
B) spleen.
C) liver.
D) bladder.
Answer: C Page Ref: 557
18) Whether an animal excretes ammonia, uric acid, or urea has mostly to do with
A) availability of water in its niche.
B) dietary strategies.
C) metabolic costs.
D) all of the above
Answer: D Page Ref: 557
19) How many moles of ATP are required to produce one mole of urea?
A) 1
B) 5
C) 10
D) 50
Answer: B Page Ref: 558
20) Which of the following is NOT a process involved in urine formation?
A) filtration
B) condensation
C) secretion
D) excretion
Answer: B Page Ref: 561
21) Which of the following is NOT a part of the nephron structure?
A) Bowman's capsule
B) proximal tubule
C) central tubule
D) distal tubule
Answer: C Page Ref: 561
22) Which of the following statements about the nephron is false?
A) The epithelial cells of the proximal tubule have numerous microvilli.
B) The wall of the ascending limb of the loop of Henle is described as "thick" or "thin" depending on the width of the tubule lumen.
C) In the distal tubule, the most common epithelial cell type has few microvilli.
D) Various regions of the nephron mediate different transport processes.
Answer: B
Page Ref: 569
23) Most solute and water reabsorption in the nephron happens at the
A) Bowman's capsule.
B) proximal tubule.
C) loop of Henle.
D) distal tubule.
Answer: B
Page Ref: 569
24) Which of the following structures is correctly matched with its function?
A) ascending limb of the loop of Henle: major site of secretion of K+
B) descending limb of the loop of Henle: major site for transport of solutes
C) proximal tubule: site of secretion of organic anions and cations
D) distal tubule: main site of reabsorption of Ca2+ and Mg2+
Answer: C
Page Ref: 569-571
25) The main ways that the nephron regulates pH of the urine is through all of the following EXCEPT
A) H+ transport.
B) HCO3- transport.
C) ammonia transport.
D) NaOH transport.
Answer: D
Page Ref: 577
26) The role of the glomerulus is to
A) provide blood to the nephron.
B) accept blood from the Bowman's capsule.
C) concentrate the urine.
D) establish osmotic gradients in the kidney medulla.
Answer: A
Page Ref: 561
27) The main forces that determine net glomerular filtration pressure include all of the following EXCEPT
A) glomerular capillary hydrostatic pressure.
B) Bowman's capsule hydrostatic pressure.
C) net oncotic pressure.
D) atmospheric pressure.
Answer: D
Page Ref: 563
28) Mesangial cells function to
A) adjust glomerular filtration rate.
B) recover solutes from primary urine.
C) adjust the size of the Bowman's capsule.
D) alter the permeability of the collecting duct.
Answer: A
Page Ref: 567
29) Vasopressin quickly increases the reabsorption of water by the collecting duct. This happens because
A) the cell transcribes and translates more aquaporins to be inserted in the membrane.
B) preformed aquaporins are translocated to the membrane.
C) phosphorylation of existing aquaporins increase their permeability.
D) All of the above are possible.
Answer: B
Page Ref: 573-574
30) Aldosterone regulates balance of
A) calcium and chloride.
B) magnesium and sodium.
C) sodium and potassium.
D) phosphates and calcium.
Answer: C
Page Ref: 575
31) Aldosterone stimulates Na+ absorption and K+ excretion in the kidney. This happens because
A) the cell transcribes and translates more ion transporters to be inserted in the membrane.
B) preformed ion transporters are translocated to the membrane.
C) phosphorylation of existing ion transporters increases their permeability.
D) All of the above are possible.
Answer: A Page Ref: 575
32) In the renin-angiotensin-aldosterone pathway that regulates blood pressure, renin is controlled in the following ways EXCEPT
A) juxtaglomerular cells themselves can sense pressure changes and release renin when blood pressure declines.
B) decreases in blood pressure activate sympathetic neurons in the medulla oblongata, triggering renin secretion.
C) macula densa cells in the wall of the distal tubule respond to a decrease in urine flow and Na+ delivery by releasing a paracrine signal that leads to renin secretion.
D) decreased perfusion of the lung leads to the production of angiotensin-converting enzyme, or ACE, that directly leads to renin secretion.
Answer: D
Page Ref: 575-576
33) In the renin-angiotensin-aldosterone pathway, angiotensin II regulates ion and water balance by doing all of the following EXCEPT
A) stimulating Na+ reabsorption in the proximal tubule.
B) stimulating vasodilation of postglomerular blood vessels.
C) stimulating the synthesis and release of other hormones that affect kidney function.
D) increasing the synthesis and release of aldosterone from the adrenal cortex.
Answer: B
Page Ref: 575-576
34) Ion and water regulation in the insect is controlled by the
A) kidney.
B) metanephridium.
C) Malpighian tubule.
D) caecum.
Answer: C
Page Ref: 581
35) Three main classes of diuretic hormones have been identified in insects. Which of the following is NOT one of those classes?
A) CRF-related diuretic hormones
B) insect myokinins
C) corticotrophin-releasing factors
D) cardioacceleratory peptides
Answer: C
Page Ref: 582
36) Compared to kidney structure in marine fish, freshwater fish have
A) a more complex glomerulus.
B) a less complex glomerulus.
C) an equally complex glomerulus.
D) no glomerulus.
Answer: A
Page Ref: 583
37) Which of the following statements is correct?
A) The complexity of the glomerulus varies among fish species, but no marine or fresh water fish can survive without a glomerulus.
B) Kidneys of amphibians have a short loop of Henle.
C) The nephrons of marine fish have longer proximal tubules and larger distal tubules compared to fresh water fish.
D) Amphibians use their bladder not only for urine storage, but also for water storage.
Answer: D
Page Ref: 583
38) The role of the loop of Henle is to produce
A) hyperosmotic urine.
B) isosmotic urine.
C) hyposmotic urine.
D) filtered urine.
Answer: A
Page Ref: 584
39) What happens if you drink a large amount of water without ingesting anything salty?
A) osmolarity of body fluid increases
B) urine volume increases
C) blood volume remains unaltered
D) blood pressure decreases
Answer: B
Page Ref: delete; not applicable to 3e
40) An animal with an internal ion profile that resembles the ion composition of the external water is an __________.
Answer: ionoconformer
Page Ref: 545
41) The force arising due to the tendency of water to move by osmosis is called __________.
Answer: osmotic pressure
Page Ref: 543
42) Animals that can tolerate only a narrow range of external osmolarity are described as __________.
Answer: stenohaline
Page Ref: 546
43) The property of an extracellular solution that determines whether a cell will swell or shrink is called __________.
Answer: tonicity
Page Ref: 30, delete, not applicable in 3e
44) Some fish, such as eels, are referred to as _______________________ since they live their adult life in freshwater but migrate to saltwater to breed. Answer: catadromous Page Ref: 550
45) The membrane-associated channel that increases the permeability of the cell to water is called an __________.
Answer: aquaporin
Page Ref: 551
46) The movement of solutes or water between adjacent cells is called __________ transport. Answer: paracellular
Page Ref: 544
47) The movement of solutes or water through epithelial cells is called __________ transport. Answer: transcellular Page Ref: 544
48) The "remodeling" of the fish gill to permit a fish to switch from freshwater to sea water is called __________.
Answer: smoltification Page Ref: 587
49) Many reptiles and birds possess a __________ that aids in ion and water balance by excreting hyperosmotic solutions of Na+ and ClAnswer: salt gland Page Ref: 586
50) Elasmobranchs have an accessory organ to help regulate salts. This organ is called the __________.
Answer: rectal gland Page Ref: 588
51) An animal that excretes most of its nitrogen in the form of ammonia is called an __________. Answer: ammoniotele Page Ref: 555
52) An animal that excretes most of its nitrogen in the form of urea is called a __________. Answer: ureotele Page Ref: 555
53) An animal that excretes most of its nitrogen in the form of uric acid is called a __________. Answer: uricotele
Page Ref: 555
54) Ammonia, uric acid, and urea are similar in that they all eliminate the element __________ from the body.
Answer: nitrogen Page Ref: 555
55) IMP stands for __________.
Answer: inosine monophosphate Page Ref: 556
56) IMP is an important compound in the metabolism of __________. Answer: uric acid Page Ref: 556
57) When urine is expelled from the bladder through the urethra, this is called __________.
Answer: micturition Page Ref: 561
58) The functional unit of the kidney is the __________.
Answer: nephron Page Ref: 561
59) In the kidney, the capacity for solute recovery is known as the __________. Answer: renal threshold Page Ref: 568
60) When an animal is dehydrated, hormones such as vasopressin lead to increased expression of __________ genes that allow water recovery.
Answer: aquaporin Page Ref: 571
61) At the glomerulus, the osmotic pressure that arises because of the protein concentration gradient is known as the __________ pressure.
Answer: oncotic Page Ref: 564
62) The brain region responsible for sensing and controlling thirst is the __________.
Answer: hypothalamus Page Ref: 580
63) Invertebrates have primitive kidneys called __________.
Answer: nephridia Page Ref: 581
64) ______________________ is the reproductive strategy of all Pacific salmon that breed only once and die shortly after.
Answer: Semelparity Page Ref: 587 (Applications 13.3)
65) There are a variety of ways that animals have adapted to cope with life in desert environments. Describe five adaptations, giving examples if appropriate, that animals might use to cope with high heat and low water availability. Answer: In Box 10.1, coping mechanisms can be broadly divided into two categories: (1) animals that resist dehydration (e.g., better at finding water) and (2) animals that tolerate dehydration. For example, desert beetles harvest water from air in the early morning, when the temperatures are low and the water condenses on the exoskeleton. Preformed water is also trapped in solid food, such as succulent cactus, which can be eaten. Water is also produced during the metabolic breakdown of dietary macromolecules. Other animals are better at storing preformed water. Some desert insects can swell in the rainy season, increasing water content dramatically. Over the course of the dry season, the insect can use this stored water for metabolic functions, until the animal is almost completely dried up.
Most desert vertebrates cannot tolerate severe dehydration, but the camel is one exception. Camels can drink excessively when water is available, up to 100 kg in 10 minutes! Also, camels gorge when food is available, and store "metabolic water" stores as fat in the hump. When food and water are scarce, the camel can draw on water stores and degrade fat in the hump to produce metabolic water.
Many animals have behavioral adaptations to help conserve water. Many animals spend the hot daylight hours underground in the cool soil or in shade to avoid evaporation of precious water stores. Additionally, staying under rocks or in burrows allows the animal to create its own microclimate. Water loss through respiration can be trapped in the burrow, providing a humid space away from the arid air. Some animals have evolved physiological adaptations to prevent water loss across the external surface. For example, desert amphibians and reptiles have skin with a thicker stratum corneum than do those that live in wetter habitats. Birds and mammals face the risk of dehydration through cutaneous water loss. While cutaneous water loss leads to body cooling, which is important, it also can lead to dehydration. To conserve more water, evaporative cooling is minimized by allowing the internal body temperature to rise. Stored heat can be released at night when it is cooler.
Other physiological processes, such as ventilation and excretion, also lead to water loss. It is no surprise that desert animals have modified these processes to minimize water loss. For example, some desert animals reduce respiratory water loss by passing expired air over a region of the nose equipped with a countercurrent heat exchanger. Moisture condenses out of the expired air before it escapes. The kangaroo rat is able to extract most of the water from its urine and feces prior to excretion. The camel blocks urination completely by storing urea within the tissues until water becomes available.
The above examples describe how animals resist dehydration. However, there are many animals that cope with dehydration. For example, some animals enter a state known as anhydrobiosis, in which the animal loses much of its water, and sometimes ALL free water. The animal will revive when water returns.
Page Ref: 553
66) Describe three specific reasons why a change in cell volume can be problematic
Answer: Cells can maintain volume by actively creating concentration gradients on either side of the membrane that induces the movement of water into, or out of, the cell. Changes in cell volume are problematic for a variety of reasons. Severely hypotonic conditions can cause a cell to explode, triggering a local immune response that can disrupt neighboring cells. Also, swollen cells can disrupt tissue structure or occlude blood vessels. When water movement changes cell volume, it also affects the intracellular concentration of metabolites and enzymes within cells, disrupting metabolic regulation. Finally, changes in cell volume can deform the cytoskeleton and plasma membrane, altering the function of receptors and transporters.
Page Ref: 544
67) What is a countercurrent multiplier, and what is its role in the loop of Henle? Briefly explain how it works. Use a diagram if necessary.
Answer: A countercurrent multiplier uses the principle of fluids flowing in opposite directions (i.e., countercurrent flow), to assist in concentrating one solution while making the other one more dilute. A countercurrent multiplier is somewhat different than a countercurrent exchanger because it requires the input of energy to help establish concentration gradients to get the system started. Countercurrent multipliers are found in the salt glands of birds and reptiles, and also in the loop of Henle in the mammalian kidney. In the loop of Henle, the countercurrent multiplier is formed by the descending and ascending paths, and along with differences in tubule permeability, it helps to establish a concentration gradient within the medulla of the kidney. This concentration gradient allows the urine to be modified in its solute concentration and volume. The loop of Henle is a part of the nephron that is folded back on itself, in hairpin fashion, so that the descending loop and the ascending loop are running countercurrent to one another. In this way, the fluid entering the nephron is continually being modified from start to finish, with the result being appropriate water and salt retention. The loop of Henle descends into the medulla of the kidney, where the osmotic gradient continues to increase deeper into the medulla. This osmotic gradient is favorable for the movement of water, and because the descending limb is selectively permeable to water (via aquaporins), water moves out of the lumen and into the interstitial space. At the bottom of the loop of Henle, the urine reaches its maximum osmolarity. The tubule then ascends toward the cortex containing highly concentrated urine, moving through interstitial fluid that is less so than before. Along with passive diffusion of salts out of the lumen, the ascending limb (which is adjacent to the descending one) ACTIVELY pumps solutes from the lumen to the interstitial fluid, increasing the osmolarity of the interstitial fluid. The input of energy allows for excessive salt pumping by the ascending limb. All together, this process creates a gradient within the medulla.
Page Ref: 569-573
68) Most teleost fish excrete ammonia. Explain why the Magadi tilapia, a fish living in highly basic water, excretes urea.
Answer: In most fish, NH3 diffusion across the gills is accelerated when external protons ionize NH3 to NH4+ . However, at a high pH (low proton concentration), this reaction is very slow, and therefore diffusion of NH3 across the gills is also very slow. These fish have an active ornithine-urea cycle in the liver, and the muscles also play an important role in urea synthesis. For these fish, excretion of urea is far more efficient.
Page Ref: 559
69) The kidney has six roles in homeostasis. Please describe them.
Answer: a. Ion balance: Some of the main ions that are important to control are Na+, K+, and Ca2+. Na+ levels are an important determinant of extracellular fluid osmolarity and water retention. K+ is important for setting membrane potentials of excitable tissues, and therefore K+ concentrations that are too high or too low can cause tissue dysfunction. Ca2+ plays a role as a macronutrient.
b. Osmotic balance: Kidneys play a role in water balance by controlling the amount of urine produced. Low water retention results in dehydration, and excessive water retention can lead to high blood pressure and edema.
c. Blood pressure: By controlling blood volume, the kidney can act to control blood pressure. The volume of the extracellular fluid is under the control of the kidney, through hormones and nerves that integrate cardiovascular conditions with the output of the central cardiovascular control center. Low blood pressure has negative impacts on the delivery of fuels to active tissue, while high pressure puts the animal at risk for damage to microvasculature.
d. pH balance: the kidney regulates the pH of extracellular fluid by retaining or excreting H+ or HCO3-
e. Excretion: The kidney plays an important role in the excretion of nitrogenous wastes as well as other water-soluble toxins.
f. Hormone production: The kidney synthesizes and releases hormones such as renin (to control blood pressure) and erythropoietin (to control red blood cell synthesis).
70) Explain the reabsorption of glucose and Na+ from the lumen of the nephron tubule into the blood, using both the Na+/K+ ATPase and Na+/glucose transporter in your answer. Use a diagram if necessary.
Answer: The concentrations of Na+ and glucose in the primary urine are not different from that of the blood, so without a concentration gradient, these compounds will not move across membranes. To overcome this problem, the Na+/K+ ATPase in the basolateral membrane of the nephron pumps sodium from the cell into the peritubular space, and this creates a favorable inward Na+ electrochemical gradient on the apical side that can be used to pull Na+ into the tubule epithelial cell from the tubule lumen. This sodium movement happens through sodium channels, Na+/H+ exchangers, or other carriers. Additionally, Na+ -coupled glucose uptake will also pull glucose into the epithelial cell through the action of a Na+ -glucose cotransporter. Concentrating glucose within the cell causes a favorable outward chemical gradient that moves glucose out of the cell into the peritubular space (via glucose permease: facilitated diffusion). Once in the peritubular space, capillaries can recover these compounds.
Page Ref: 567-568
71) What happens to a rat that has had its adrenal gland removed? Why?
Answer: The adrenal gland secretes aldosterone which plays a role in Na+ absorption (and secondarily water recovery) and enhances K+ excretion in the kidney. Aldosterone targets the principal cells of the distal tubule and collecting ducts, binding to a cytoplasmic hormone receptor and entering the nucleus to stimulate transcription of genes involved in ion transport. Beginning a few hours after removal of the adrenal gland, the rat produces copious amounts of urine, high in Na+ and low in K+, as would be expected based on the role of aldosterone. Over time, the animal dehydrates as it draws fluids from the extracellular spaces to maintain blood volume and pressure.
Page Ref: 575-576
72) Describe the three main classes of diuretic hormones found in insects.
Answer: 1) Insect myokinins are short peptide hormones that act on the stellate cells of the Malpighian tubules. They activate phospholipase C, which increases production of IP3, which causes the release of Ca2+ The increased concentration of Ca2+ results in Cl- transport into the lumen. This movement of Ca2+ causes the parallel movement of Na+ and Cl- , which then leads to a net movement of NaCl and KCl from the hemolymph into the lumen.
2) Cardioacceleratory peptides increase heart rate and stimulate secretion of fluids into the Malpighian tubules. These hormones stimulate phospholipase C, which increases production of IP3 and release of Ca2+ The Ca2+ activates the Ca2+ calmodulin-dependent nitric oxide synthase and guanylyl cyclase, which results in the increase of H+ ATPase activity.
3) Fifteen different CRE-related diuretic hormones are found in insects. These hormones stimulate synthesis of cAMP in Malpighian tubule cells, which stimulates cation transport at the basal and apical regions of the principal cells.
Page Ref. 582
73) What information have conservation physiologists uncovered about possible reasons that some sockeye salmon breed successfully while others are unsuccessful at reproduction?
Answer: Sockeye salmon are anadromous; young hatch in freshwater rivers, then several years later migrate to the ocean where they continue to grow and mature before migrating back to their birthplace to spawn and die. When salmon move from saltwater to freshwater, their gills must undergo a transition from an ion secreting epithelium in saltwater to an ion absorbing epithelium in freshwater. When the shift between the two types of epithelia occurs, there is a change in the expression of genes that encode the sodiumpotassium pump. The isoform, Na+/K+ ATPase α1a, is expressed mostly in the freshwater epithelium, while the isoform called Na+/K+ ATPase α1b, is mostly expressed when fish enter saltwater. When salmon migrate from saltwater to freshwater to breed, there is an increase in the amount of mRNA coding for Na+/K+ ATPase α1a in the gill, indicating the shift from ion secretion to ion absorption. Researchers discovered a "mortality-related signature" of gene expression in gills that help identify which fish are successful in reaching spawning grounds and which are not. Fish that were not successful in reaching spawning grounds tended to undergo the transformation from ion-secreting to ion-absorbing epithelium while still living in saltwater. In contrast, fish that successfully reached spawning grounds underwent the gill transformation only when they reached fresh water. It appears that a premature shift in the transformation process may have a detrimental effect on fish’s osmoregulation, so they may be in poorer condition by the time they reach freshwater.
Page Ref: 587 (Application 13.3)
Chapter 14 Digestion and Energy Metabolism
1) Which statement(s) is (are) true with respect to the giant vent worms (Riftia pachyptila)?
A) These worms have a complete digestive tract.
B) Nutrients are derived from a trophosome filled with chemolithotrophic bacteria.
C) The worm’s hemoglobin transports hydrogen sulfide and oxygen to its symbiont.
D) B and C
Answer: D
Page Ref: 593
2) Digestive physiology is concerned with
A) the sensory system employed to locate food.
B) the mechanical disruption of food.
C) the chemical conversion of food molecules into transportable forms.
D) all of the above
Answer: D
Page Ref: 593
3) Which of the following is the standard unit of measurement that describes the energy of
dietary items?
A) joules
B) moles
C) B.T.U.
D) °C
Answer: A Page Ref: 595
4) The same caloric equivalent of a gram of protein or carbohydrate is
A) 2 kcal.
B) 4 kcal.
C) 9 kcal.
D) 12 kcal.
Answer: B Page Ref: 595
5) Which one of the following vitamins is fat soluble, can be stored, and has the potential to be toxic?
A) vitamin A
B) niacin (B3)
C) riboflavin (B2)
D) vitamin C
Answer: A Page Ref: 595
6) The root cause of beriberi is
A) vitamin C deficiency.
B) thiamine deficiency.
C) niacin deficiency.
D) vitamin D deficiency.
Answer: B Page Ref: 596
7) Which vitamin plays a major role in the absorption of dietary calcium (Ca2+)?
A) vitamin A
B) vitamin C
C) vitamin D
D) vitamin E
Answer: C Page Ref: 596
8) Of the 20 amino acids that animals use to construct proteins, how many are essential?
A) 8
B) 10
C) 12
D) all 20
Answer: A Page Ref: 596
9) Which one of the following enzymes is incorrectly paired with its substrate?
A) lipase : triglycerides
B) trypsin : proteins
C) amylase : polysaccharides
D) nuclease : oligosaccharides
Answer: D Page Ref: 597
10) Whales house chitinolytic bacteria in their
A) esophagus
B) crop
C) ceca
D) stomach
Answer: C Page Ref: 598
11) Which of the following generally passes through the GI tracts of animals undigested?
A) glycogen
B) disaccharides
C) cellulose
D) proteins
Answer: C Page Ref: 598
12) The bacterium, Clostridium difficile,
A) is readily treated with drugs.
B) is dangerous because it causes severe digestive dysfunction.
C) is outcompeted by ingesting "good" bacteria.
D) A and B
Answer: B
Page Ref: 599 (Applications 14.1)
13) Animals have been shown to increase the total number of SGLT-1 transporters in the gut by
A) producing more transporters per unit surface area of the gut.
B) increasing the surface area of the gut per unit length.
C) increasing the total length of the intestine.
D) all of the above
Answer: D Page Ref: 61
14) Pancreatic proteases include which of the following?
A) trypsin
B) chymotrypsin
C) carboxypeptidase
D) all of the above
Answer: D
Page Ref: 61
15) By which process do the fatty acids and monoglycerides of micelles cross the enterocyte cell
membra nes?
A) active transport
B) diffusion
C) pinocytosis
D) phagocytosis
Answer: B Page Ref: 613
16) What is the composition of bile?
A) cholesterol
B) phospholipids
C) pigments and salts
D) all of the above
Answer: D Page Ref: 613
17) Which type of lipoprotein is synthesized by the enterocytes of the small intestine?
A) chylomicron
B) VLDL
C) LDL
D) HDL Answer: A Page Ref: 614
18) The most important phagostimulants of insects are
A) Sugars.
B) amino acids.
C) fatty acids.
D) both A and B Answer: D Page Ref: 599
19) Lacking a mouth and digestive system, in many ways the anatomy of this invertebrate resembles that of a gut turned inside out.
A) sponge
B) Hydra
C) cestode
D) sea urchin
Answer: C Page Ref: 600
20) Which animal is incorrectly matched with the anatomical feature associated with feeding?
A) sponge : choanocytes
B) Hydra : tentacles
C) snail : radula
D) spider : proboscis
Answer: D Page Ref: 600-601
21) The beak of birds is covered by a sheath of overlapping keratin scales called the A) rhamphotheca.
B) rostrum.
C) osculum.
D) manubrium.
Answer: A Page Ref: 601
22) The four types of teeth that occur in mammals are the
A) incisors, molars, precanines, and canines.
B) incisors, bicuspids, tricuspids, and canines.
C) incisors, canines, premolars, and molars.
D) incisors, canines, epimolars, and molars.
Answer: C Page Ref: 603
23) The enamel of the mammalian tooth is composed of crystals of
A) calcium carbonate.
B) calcium fluoride.
C) calcium phosphate.
D) calcium chloride.
Answer: C Page Ref: 602
24) A two-way gut system (i.e., gastrovascular cavity) is a characteristic of
A) platyhelminths.
B) annelids.
C) arthropods.
D) molluscs.
Answer: A Page Ref: 605
25) The space between the body wall and the GI tract of vertebrates is known as the A) gastric vestibule.
B) peritoneal cavity.
C) visceral mass.
D) abdominal lumen.
Answer: B Page Ref: 605
26) Although derived from three germ layers, the __________ lack coeloms.
A) cnidarians
B) platyhelminths
C) rotifers
D) nematodes
Answer: A Page Ref: 605
27) During development in __________, the blastopore develops into the anus and the mouth is
secondar ily derived.
A) molluscs
B) annelids
C) arthropods
D) echinoderms
Answer: D Page Ref: 605
28) During embryonic development in vertebrates, the foregut gives rise to the
A) esophagus.
B) stomach.
C) anterior region of the duodenum.
D) all of the above
Answer: D Page Ref: 605
29) The upper GI tract of __________ is more complex than that of other vertebrates due to the presence of a crop.
A) sharks
B) amphibians
C) reptiles
D) birds
Answer: D Page Ref: 607
30) What is the function of saliva?
A) initiation of enzymatic degradation
B) lubrication and dissolution of ingested food
C) antimicrobial cleansing of the mouth
D) all of the above
Answer: D Page Ref: 608
31) The interior lining of the stomach is composed of __________ epithelial cells.
A) squamous
B) cuboidal
C) columnar
D) transitional Answer: C Page Ref: 608
32) Of the cells lining the gastric pits of the stomach, which does NOT secrete a substance into the lumen?
A) mucous neck cells
B) parietal cells
C) chief cells
D) enteroendocrine cells
Answer: D Page Ref: 609
33) Moving from the lumen outward, which of the following describes the correct order of the layers comprising the intestinal wall?
A) mucosa, submucosa, circular smooth muscle, longitudinal smooth muscle
B) circular smooth muscle, longitudinal smooth muscle, mucosa, submucosa
C) circular smooth muscle, mucosa, submucosa, longitudinal smooth muscle
D) submucosa, mucosa, circular smooth muscle, longitudinal smooth muscle
Answer: A Page Ref: 609
34) The __________ layer of the intestinal wall is primarily composed of connective tissue.
A) mucosa
B) submucosa
C) circular smooth muscle
D) longitudinal smooth muscle
Answer: B Page Ref: 610
35) __________ is a hormone secreted by the stomach that stimulates appetite.
A) Gastrin
B) Ghrelin
C) Leptin
D) Secretin
Answer: B Page Ref: 615
36) __________ is an appetite-suppressing hormone secreted by white adipose tissue.
A) Gastrin
B) Ghrelin
C) Leptin
D) Secretin
Answer: C Page Ref: 615
37) The mechanism of acid secretion by the parietal cells of the stomach involves the actions of the
A) enzyme pepsid anhydrase.
B) K+/H+ ATPase proton pump.
C) Cl-/H+ exchanger.
D) all of the above
Answer: B Page Ref: 617
38) Treatments for excessive stomach-acid secretion target the
A) K+/H+ ATPase proton pump of the parietal cells.
B) H2 receptors of the parietal cells.
C) neuroendocrine G cells of the stomach that release gastrin.
D) both A and B
Answer: D
Page Ref: 618
39) What is the role of the myenteric plexus?
A) regulation of gut motility and enzyme secretion
B) ion and water transport by the gut
C) regeneration of the intestinal epithelium and mucus secretion
D) all of the above
Answer: A
Page Ref: 619
40) Hyperphagy
A) is an important adaptation for survival in all animals, including humans.
B) is common in large mammals, but rare in small mammals and birds
C) translates into fat deposition, which is important for migration, reproduction, and dormancy.
D) A and C
Answer: C
Page ref: 624 (Challenges to Homeostasis 14.3)
41) Which of the following events is most likely to occur when blood glucose levels are high and the pancreas responds by secreting insulin?
A) glycogen breakdown in the liver is stimulated
B) adipose tissue uptake of glucose and its conversion to triglycerides is stimulated
C) down regulation of the GLUT-4 transporter in skeletal muscle
D) all of the above
Answer: B
Page Ref: 626
42) __________ are most important as part of a metabolic stress response.
A) Glucocorticoids
B) Insulin and glucagon
C) Epinephrine and norepinephrine
D) Acetylcholine and nitric oxide
Answer: A
Page Ref: 626
43) Glucocorticoids serve which of the following functions?
A) induction of gluconeogenesis
B) reduction of glucose uptake by peripheral tissues
C) mobilization of triglycerides in the form of fatty acids
D) all of the above
Answer: D
Page Ref: 626
44) The function of adipokinetic hormone in insects is the
A) mobilization of energy stores of the fat body.
B) stimulation of the corpora cardiacum to release ecdysteroids.
C) conversion of flight muscle proteins into the blood sugar trehalose.
D) all of the above
Answer: A
Page Ref: 626
45) During long-term starvation,
A) glycogen stores become depleted.
B) skeletal muscle experiences protein degradation.
C) fatty acids and amino acids are converted into ketone bodies.
D) all of the above
Answer: D
Page Ref: 626
46) What accounts for the differences in metabolic rates of animals?
A) body size
B) activity level
C) temperature
D) all of the above
Answer: D
Page Ref: 627
47) Adipose tissue acts as an endocrine tissue, playing roles related to
A) inflammation.
B) blood clotting and blood pressure.
C) dietary status.
D) all of the above
Answer: D
Page Ref: 625
48) The main metabolic effects of obesity include all but which one of the following?
A) high blood pressure
B) insulin resistance
C) low blood glucose levels
D) low HDL
Answer: C
Page Ref: 625
49) The gross energy of food materials can be quantified experimentally using the technique known as __________.
Answer: calorimetry
Page Ref: 628
50) The heat generated in the body of an endotherm from its ingested food is known as the __________.
Answer: specific dynamic action
Page Ref: 595
51) _____________ is the bacterium that causes gastric ulcers.
Answer: Helicobacter pylori
Page Ref: 599 (Applications 14.1)
52) Protein digestion takes place in the __________ and the __________.
Answer: stomach; small intestine
Page Ref: 612
53) In the small intestine, the __________ and __________ found in bile act in concert to organize lipids into small droplets called micelles.
Answer: phospholipids; salts
Page Ref: 613
54) __________ are lipid complexes synthesized by the cells of the small intestine and released into circulation by way of the lymph.
Answer: Chylomicrons
Page Ref: 614
55) The middle layer of the mammalian tooth is a living tissue known as the __________.
Answer: dentin
Page Ref: 602
56) The early embryonic gut of vertebrates is derived from the __________.
Answer: endoderm
Page Ref: 605
57) The functional length of the straight gut of a shark is increased by an internal membranous network known as the __________.
Answer: spiral valve
Page Ref: 606
58) The surface area of enterocytes is increased by the presence of microscopic protrusions called __________.
Answer: microvilli
Page Ref: 607
59) In one-way digestive tracts, muscular valves called __________ control the passage of food from one compartment to the next.
Answer: sphincters
Page Ref: 607
60) Bile is produced by the __________ and stored in the __________.
Answer: liver; gallbladder
Page Ref: 610
61) Pancreatic proteases are produced in an inactive form called __________.
Answer: proenzymes
Page Ref: 610
62) Peptide YY, leptin, and ghrelin, the appetite-controlling hormones, exert their effects on the region of the brain called the __________.
Answer: hypothalamus
Page Ref: 615
63) The secretion of pepsinogen by the chief cells of the gastric pits is induced by the hormone __________.
Answer: gastrin
Page Ref: 618
64) __________ is the slow wave of contraction that progresses down the GI tract to push food along its length.
Answer: Peristalsis
Page Ref: 619
65) __________ is the hormone antagonist of insulin.
Answer: Glucagon
Page Ref: 623
66) When blood glucose levels are high, the __________ cells of the pancreas respond by secreting insulin.
Answer: beta Page Ref: 623
67) In the insects, the product of the corpora cardiacum called __________ triggers the mobilization of triglycerides stored in the fat body.
Answer: adipokinetic hormone (AdK)
Page Ref: 626
68) Nervous tissue relies almost exclusively on __________ as fuel. Answer: glucose Page Ref: 626
69) Insulin insensitivity causes the liver to __________ (increase or decrease) lipid storage. Answer: increase Page Ref: 625
70) In vertebrates, early starvation is characterized by utilization of stored _____________ and ___________ to meet the metabolic needs of tissues.
Answer: glycogen, triglycerides
Page Ref: 627
71) Describe the various forms of energy that are NOT available from the food an animal ingests.
Answer: The total or gross energy of ingested food consists of two components: digestible energy and indigestible energy, the latter of which takes the form of feces. Of the digestible energy, some is unmetabolizable, leaving the body as urine. The remaining metabolizable energy is usable net energy and specific dynamic action (or body heat).
Page Ref: 595
72) Describe the processes by which animals can produce de novo a variety of fatty acids that differ in chain length and desaturation.
Answer: Using the enzyme fatty acid synthase, acetyl CoA can be converted in palmitate and subsequently lengthened into other fatty acids via elongases. Double bonds are
introduced via desaturases.
Page Ref: 597
73) Why do animals require lipids for normal physiological function? While animals can produce some fatty acids on their own (de novo), others must be acquired from the diet. Which are the two essential fatty acids that animals cannot manufacture themselves, and what are their sources?
Answer: Animals require lipids for a variety of functions, including phospholipids to build cell membranes, triglycerides to provide metabolic energy, and other lipids to serve in cell signaling.
Animals cannot manufacture omega-6 (linoleic acid) and omega-3 (alphalinolenic acid) fatty acids, and therefore need to obtain both from their diet. Fish is the best source of omega-3 fatty acids, while plant seeds are high in omega-6 fatty acids.
Page Ref: 597
74) What is the importance of digestive enzymes? Briefly describe the four different classes of enzymes that most animals utilize, despite the fact that there is a large variation in diet in the animal kingdom.
Answer: Animals require enzymes to convert the large macromolecules that they obtain in their food into smaller molecules that can be absorbed. 1) Amylases, such as glucoamylases, break down polysaccharides into oligosaccharides. Disaccharidases, such as lactase, break down disaccharides into monosaccharides. 2) Lipases, such as triglyceride lipases, break down triglycerides and release fatty acids, while phospholipases release fatty acids from phospholipids. 3) Proteases, such as trypsin, break down large proteins into smaller polypeptides. Amino-peptidases break the first N terminal peptide bond, while carboxy peptidases break the last C-terminal peptide bond. 4) Nucleases are responsible for breaking up DNA into nucleotides, which are then further broken down into nitrogenous bases for absorption.
Page Ref: 597
75) Describe the process of the enzymatic digestion of carbohydrates.
Answer: Starch and glycogen are converted into oligosaccharides and disaccharides by the actions of salivary and pancreatic amylases. Specific disaccharidases in the duodenum convert disaccharides into monosaccharides that are then absorbed by the intestinal epithelium.
Page Ref: 611
76) What is the mechanism by which the glucose transporter SGLT-1 increases the ability of the small intestine to absorb glucose?
Answer: The SGLT-1 transporter serves as a glucose sensor that triggers a signaling pathway leading to the rapid synthesis of another glucose transporter, GLUT-2, and its intracellular transport to the microvilli.
Page Ref: 612
77) Describe the processing of vegetation through the stomach of a ruminant.
Answer: Vegetation enters the first pair of compartments, the rumen and reticulum, where
fermentative bacteria digest the cellulose. The partially processed food is regurgitated, chewed, and then passed through the esophagus to the second set of stomachs, the omasum and abomasum. The abomasum secretes digestive enzymes to serve as the glandular stomach.
Page Ref: 607
78) Explain how the molecular structure of bile salts permits them to function as emulsifiers.
Answer: Bile salts are amphipathic molecules with a polar region that interacts with water and a nonpolar region that binds to fats. By coating the surface, the fat droplets are stabilized in the aqueous solution of the intestine.
Page Ref: 610
79) Describe the events of the trypsinogen cascade.
Answer: The three pancreatic proteases are secreted as inactive proenzymes to protect the secreting cells from proteolytic degradation. Upon entering the lumen of the duodenum, trypsinogen is cleaved into active trypsin by a membrane-bound enterokinase. Trypsin then converts chymotrypsinogen and procarboxypeptidase into chymotrypsin and carboxypeptidase, respectively, via enzymatic cleavage.
Page Ref: 610
80) Describe the roles of leptin, ghrelin, and peptide YY in regulating appetite.
Answer: Ghrelin is an appetite-stimulating hormone that is released by gastric cells when the stomach is empty. In contrast, peptide YY is released by enteroendocrine cells to inhibit hunger when the colon is full. Both have short-term effects, whereas leptin, secreted by white adipose tissue, serves as a long-term suppressor of appetite based on the body's fat stores.
Page Ref: 616-617
81) Describe the series of events triggered by the entry of acidic stomach contents into the duodenum.
Answer: The sudden change in acidity triggers the duodenal release of secretin and vasoactive peptide (VIP) into the bloodstream to induce the pancreatic secretion of bicarbonate. Cholecystokinin (CCK), released into the bloodstream by other intestinal cells in response to lumenal amino acid and fatty acid levels, acts on the pancreas to stimulate digestive enzyme secretion and on the gallbladder to trigger the release of bile via smooth muscle contractions.
Page Ref: 618
82) What is the role played by adipokinetic hormone in the regulation of insect flight?
Answer: During energy-demanding activities such as flight, adipokinetic hormone (AdK) is released by the corpora cardiacum and stimulates the mobilization of insect fat body lipid and glycogen stores. The resultant mobilized products (i.e., DAG, fatty acids, and trehalose) provide energy to the flight muscles.
Page Ref: 626
Chapter 15 Thermal Physiology
1) Some fish have the ability to keep certain parts of their body warm by the use of retia.
Retia are
A) countercurrent heat exchangers
B) found in locomotor muscles of certain species of large fish, such as tuna and lamnid sharks.
C) special adipose cells that generate heat.
D) A and B
Answer: D Page Ref: 635
2) At which of the following systems would environmental temperatures be the most variable?
A) hydrothermal vents
B) cave systems
C) bathypelagic systems of the world's oceans
D) alpine terrestrial systems
Answer: D
Page Ref: 636
3) The exchange of thermal energy between an animal and its environment can occur by
A) conduction and convection.
B) radiation.
C) evaporation.
D) all of the above
Answer: D
Page Ref: 637
4) Which one of the following has the highest thermal conductivity?
A) fat
B) air
C) water
D) rock
Answer: D
Page Ref: 638
5) Radiant heat from the body of an animal is described by
A) the Nernst equation.
B) the Stefan-Boltzmann equation.
C) Fourier's law.
D) Q10.
Answer: B Page Ref: 638
6) From among the following list of animals, which would lose heat at the fastest rate per unit mass?
A) bear
B) mouse
C) rabbit
D) wolf
Answer: B
Page Ref: 639
7) According to Bergmann's and Allen's rules, brown bears living in temperate regions would be __________ than those living in the arctic.
A) larger with shorter limbs
B) smaller with shorter limbs
C) larger with longer limbs
D) smaller with longer limbs
Answer: D
Page Ref: 639
8) In animals insulated with fur or feathers, __________ heat loss is reduced.
A) convective
B) conductive
C) radiant
D) more than one of the above
Answer: B
Page Ref: 640
9) Which of the following is most synonymous with the term ectotherm?
A) heterotherm
B) poikilotherm
C) endotherm
D) pseudotherm
Answer: B
Page Ref: 641
10) Which of the following animals would be classified as a homeotherm?
A) polar fish
B) Burmese python
C) marine iguana
D) more than one of the above
Answer: A
Page Ref: 641
11) A __________ is an example of a temporal heterotherm.
A) python
B) swordfish
C) hummingbird
D) laminid shark
Answer: A Page Ref: 642
12) Temporal heterothermy
A) benefits ectotherms by enabling them to reach the thermoneutral zone.
B) benefits ectotherms by allowing them to increase their metabolism, which speeds up digestion, nutrient absorption, and biosynthesis.
C) benefits endotherms by enabling them to conserve energy when temperatures are cold.
D) B and C
Answer: D Page Ref: 642
13) A __________ heterotherm can retain heat in certain parts of its body.
A) temporal
B) spatial
C) positional
D) regional
Answer: D Page Ref: 642
14) The __________ of a resting homeotherm is the range of ambient temperature where its metabolic rate is minimal.
A) thermoneutral zone
B) preferred temperature
C) optimal temperature range
D) idealized thermal region
Answer: A Page Ref: 643
15) If the body temperature of an endothermic homeotherm falls below the __________ temperature, the metabolic rate increases.
A) upper critical
B) lower critical
C) incipient upper lethal
D) incipient lower lethal
Answer: B Page Ref: 643
16) A(n) __________ cannot tolerate a wide ambient temperature range.
A) ectotherm
B) poikilotherm
C) eurytherm
D) stenotherm
Answer: D
Page Ref: 642
17) Of the major classes of macromolecules, only __________ are substantially affected by temperature over the normal range experienced by animals.
A) proteins and lipids
B) carbohydrates
C) nucleic acids
D) all of the above
Answer: A
Page Ref: 645
18) In the process of homeoviscous adaptation, cells
A) alter rates of chemical reactions.
B) alter membrane fluidity.
C) alter isozyme ratios.
D) switch to alternative biochemical pathways.
Answer: B
Page Ref: 647
19) __________ is essentially the ratio between reaction rates of a process adjusted for a 10°C temperature difference.
A) Q10
B) An Arrhenius plot
C) Km
D) Homeoviscous adaptation
Answer: A
Page Ref: 650
20) Membrane fluidity can be increased by __________ of the plasma membrane.
A) increasing the lengths of fatty acid chains
B) decreasing the number of double bonds in the fatty acids
C) decreasing the phosphatidylcholine to phosphatidylethanolamine ratio
D) decreasing the cholesterol content
Answer: C
Page Ref: 647
21) If the catalytic activity of an enzyme doubles with a biologically relevant 10°C increase in temperature, then Q10 would be near the value of
A) 2.
B) 5.
C) 10.
D) 20.
Answer: A
Page Ref650 and Box 15.2
22) The observation that a given enzyme retains its kinetic properties in different species adapted to different temperature regimes is a phenomenon known as
A) Arrhenius effect.
B) Q10.
C) conservation of Km
D) homozyme stability.
Answer: C
Page Ref649
23) Temperature-dependent remodeling may involve qualitative strategies such as
A) changes in mitochondrial density of muscle fibers.
B) hypertrophic growth of the heart.
C) seasonal differential expression of myosin isoforms.
D) variable levels of myoglobin concentrations.
Answer: C
Page Ref: 649
24) Organisms that thrive in the extreme cold are known as
A) psychrotrophs.
B) cryomorphs.
C) mesotrophs.
D) picnomorphs.
Answer: A Page Ref: 651
25) Cold-adapted enzymes are more efficient at low temperatures than their warm-adapted counterparts due to their
A) increased stability.
B) reduction in weak bonds that stabilize the three-dimensional structures.
C) higher proportion of hydrogen bonds.
D) more than one of the above
Answer: B
Page Ref: 652
26) __________ are able to survive without expressing functional myoglobin.
A) Coral reef damsel fish
B) Salmon
C) Polar bears and other arctic mammals
D) Antarctic fish
Answer: D Page Ref: 652
27) During times of thermal stress, heat shock proteins act as
A) chaperones to assist in the refolding of proteins.
B) transcriptional activators that ultimately lead to altered membrane lipids.
C) intercellular cytokine messengers that trigger adaptive responses in adjoining cells.
D) more than one of the above
Answer: A Page Ref: 652
28) __________ have lost the ability to mount a heat shock response.
A) Antarctic fish
B) Fruit flies
C) Reindeer
D) Bluefin tuna
Answer: A Page Ref: 652
29) Ice crystals forming within tissues are detrimental due to the
A) piercing of cell membranes.
B) generation of hyperosmotic stress.
C) loss of membrane fluidity.
D) all of the above
Answer: D Page Ref: 653
30) In some freeze-tolerant animals, intracellular ice crystal formation is prevented by the presence of
A) proton pumps.
B) antifreeze proteins.
C) heat shock proteins.
D) hydration elements.
Answer: B Page Ref: 654
31) To date, __________ classes of antifreeze proteins have been identified.
A) 2
B) 3
C) 4
D) 5
Answer: C Page Ref: 654
32) The antifreeze glycoproteins (AFGPs) share a common ancestry with
A) heat shock proteins.
B) pancreatic trypsinogen.
C) cytoskeletal actin.
D) Ca2+ -dependent lectin.
Answer: B Page Ref: 655
33) The ability to produce endogenous body heat is known as
A) metabolic hyperthermy.
B) mesothermy.
C) thermogenesis.
D) oxidative metabolism.
Answer: C Page Ref: 655
34) Shivering thermogenesis of many birds and mammals is associated with
A) white adipose tissue.
B) cardiac muscle tissue.
C) brown adipose tissue.
D) skeletal muscle tissue.
Answer: D Page Ref: 657
35) Most thermogenic pathways of futile cycling involve cycling between the hydrolysis and synthesis of
A) heat shock proteins.
B) fatty acids.
C) glucose-6-phosphate.
D) ATP.
Answer: D Page Ref: 656
36) The mechanism by which bumblebees and certain moths generate preflight heat in thoracic muscles involves
A) a metabolic futile cycle in carbohydrate metabolism
B) the simultaneous contraction of antagonistic flight muscles.
C) rapid wing movement that avoids lift.
D) all of the above
Answer: D Page Ref: 657
37) Typically,an endotherm has a resting metabolic rate that is __________ higher than that of an ectotherm of equivalent size.
A) 2-fold
B) 5-fold
C) 10-fold
D) 20-fold
Answer: C Page Ref658
38) BAT growth and thermogenesis are under the control of the
A) central nervous system.
B) sympathetic nervous system.
C) parasympathetic nervous system.
D) all of the above
Answer: B Page Ref: 658
39) In brown adipose tissue, thermogenin inserts into the inner mitochondrial membrane and serves to
A) uncouple oxidation from phosphorylation.
B) enhance the proton motive force.
C) eliminate two of the steps of electron transport.
D) more than one of the above
Answer: A Page Ref: 658
40) In mice, the overexpression of a transcription factor PRDM16, results in an increase in BAT, which appears to be important
A) as an uncoupling protein
B) in decreasing mitochondrial respiration
C) in protection against metabolic dysfunctions, such as obesity.
D) in ATP production.
Answer: C Page Ref: 659 (Box 15.3)
41) The central thermostat of birds appears to reside in the
A) atrial wall.
B) adrenal cortex.
C) hypothalamus.
D) spinal cord.
Answer: D Page Ref661
42) The reduction of heat loss via piloerection is a phenomenon commonly observed in
A) birds and mammals.
B) heterothermic fish.
C) large flying insects.
D) marine reptiles.
Answer: A Page Ref: 661
43) What do the red muscles of tuna, the optical systems of billfish, and the legs of birds have in common?
A) higher proportions of glycolytic muscle fibers
B) brown adipose tissue
C) countercurrent heat exchangers
D) more than one of the above
Answer: C Page Ref: 662-663
44) What is the primary role of salt as a constituent of sweat in evaporative cooling systems?
A) boiling point elevation
B) water balance
C) blood pressure regulation
D) electrolyte adjustment
Answer: A Page Ref: 663
45) Many animals exhibit a daily hypometabolic state known as
A) estivation.
B) endothermy.
C) hibernation.
D) torpor.
Answer: D Page Ref: 665
46) As compared to cooler regions, in the warmer regions of their habitats, reindeer are able to reduce body temperature more effectively by
A) breathing through their nostrils.
B) increasing the rates of evaporative cooling from their ears.
C) switching to glycolysis in their brain stems.
D) panting and increasing the breathing frequency.
Answer: D Page Ref: 664
47) __________ is the ability to generate and maintain elevated body temperatures.
Answer: Endothermy Page Ref: 634
48) The independent routes to endothermy of birds and mammals can be explained by the ________________evolution of insulation.
Answer: convergent Page Ref: 635
49) In biological systems, radiant heat exchange occurs through electromagnetic radiation in the __________ range.
Answer: infrared Page Ref: 637
50) A __________ is an animal with a body temperature that varies in response to environmental conditions.
Answer: poikilotherm Page Ref: 641
51) The relatively constant temperature of the deep, internal region of a homeotherm is known as the __________ temperature.
Answer: core Page Ref: 642
52) A __________ heterotherm can retain heat in certain parts of the body.
Answer: regional Page Ref: 642
53) The range of __________ is the difference between the incipient upper and lower lethal temperatures.
Answer: tolerance Page Ref: 643
54) Cells can remodel their membranes to preserve fluidity in a process known as __________ adaptation.
Answer: homeoviscous Page Ref: 647
55) In the natural world, the complex response of an animal to seasonal changes in temperature is known as __________.
Answer: acclimatization Page Ref: 649
56) __________ are animals that thrive in the extreme cold.
Answer: Psychrotrophs Page Ref: 651
57) Thermogenic pathways rely on __________ cycling in which chemical potential energy is spent to generate heat.
Answer: futile Page Ref: 656
58) The use of skeletal muscles to generate heat in birds and mammals is referred to as __________. (two words)
Answer: shivering thermogenesis Page Ref: 656
59) Typically located near the backs and shoulders, __________ tissue is particularly important for thermogenesis in small mammals and newborns of larger mammals.
Answer: brown adipose Page Ref: 658
60) In animals, regulating how much blood flows into the vasculature is referred to as the response.
Answer: vasomotor
Page Ref: 661
61) The raising of individual hairs in mammals to increase the insulation capacity of the fur is a process known as __________.
Answer: piloerection
Page Ref: 661
62) __________ is a cooling behavior seen in birds and is characterized by rapid contraction and relaxation of throat muscles.
Answer: Gular fluttering
Page Ref: 663
63) Name and briefly define the four routes by which heat is transferred between an animal and its environment.
Answer: Conduction is the transfer of thermal energy from one region of an object or fluid to another. Convection is the transfer of thermal energy between an object and a moving external fluid. Radiation, usually in the form of infrared radiation, is either absorbed by or emitted from an animal. Lastly, evaporation of water molecules from the surface of an object absorbs thermal energy from the object during the phase change.
Page Ref: 637
64) Citing two examples, explain how an animal can alter its surface area to volume ratio to reduce heat loss?
Answer: Individual organisms can curl their bodies to effectively reduce their surface area to volume ratios. When a python rolls itself into a ball, the exposed surface area is reduced as much as 85%. Groups of organisms can attain similar results by huddling: Colonies of naked mole rats can maintain a constant body temperature by huddling, whereas an individual will experience a significant loss of body heat if the ambient temperature drops.
Page Ref: 639-640
65) What are the four mechanisms by which cells can remodel membranes to preserve fluidity?
Answer: The length of fatty acid chains of phospholipids can be shortened, reducing the number of intermolecular bonds and viscosity. Intermolecular bonds between fatty acid chains can also be reduced through bends in the chains by introducing double bonds. Changing the polar heads of phospholipids can reduce the polar interactions between the membrane and its environment: decreasing the phosphatidylcholine to phosphatidylethanolamine ratio reduces the viscosity. And lastly, increasing the concentration of cholesterol increases membrane fluidity at lower temperatures.
Page Ref: 645, 647
66) How have selective pressures altered the expression of the LDH-B gene among populations of killifish living along the eastern coast of North America?
Answer: Different alleles for the LDH-B gene exist in the killifish populations with different levels of expression. One allele predominates in northern populations; another predominates in southern populations. Due to mutations in the promoter, the northern allele is expressed at twofold higher levels to compensate for the effects of temperature on enzyme activity.
Page Ref: 649
67) Describe the molecular events of the heat shock response involving Hsp70.
Answer: When temperatures are elevated, usually by just a few degrees, the complex of heat shock protein 70 (Hsp70) and heat shock factor (HSF) monomers in the cytoplasm dissociate and Hsp70 binds to denatured proteins to act as chaperones. The HSF monomers assemble into trimers, migrate into the nucleus, and bind to the promoters of genes with heat shock elements. Transcription of Hsp70 increases, ultimately resulting in the formation of more Hsp70/HSF complexes and cessation of the transcriptional cascade.
Page Ref: 652
68) Describe the three preflight mechanisms of regional heterothermy observed in bumblebees and large flying moths.
Answer: First, a metabolic futile cycle involving two opposing enzymes results in ATP hydrolysis and heat production in the thorax. Second, two sets of antagonistic flight muscles can engage in a pattern of simultaneous contractions to generate heat without producing movement. And third, rapid wing movement generates heat, but by controlling the frequency and orientation of the wings, no lift is produced.
Page Ref: 657
69) What is BAT and what role does it play in animal physiology?
Answer: BAT is brown adipose tissue found along the back and shoulder regions of small mammals. BAT plays an important role in thermogenesis, because it generates heat in newborn mammals and small mammals that live in cold environments. BAT heat is referred to as nonshivering thermogenesis and a key feature of BAT is the protein thermogenin. In the mitochondrial membrane, thermogenin stimulates the rate of mitochondrial respiration and heat production. Normally, mitochondria produce ATP, but thermogenin uncouples mitochondria, dissipating the proton gradient so ATP cannot be produced, but instead heat is generated
Page Ref: 658
70) Describe the vasomotor response observed in the skin of animals.
Answer: Heat is lost as blood travels through the vasculature of the skin. The pattern of flow can be altered by arteriovenous shunts known as arteriovenous anastomoses. Under warm environmental conditions, the shunts are constricted, forcing blood near the surface to enhance heat loss; when dilated, the blood travels deeper beneath the skin and heat loss is reduced.
Page Ref: 661-662
71) Describe how birds and mammals lose heat through ventilation.
Answer: Birds and mammals have respiratory surfaces that are well adapted for gas exchange, so in these animals we see high vascularity, moist surfaces, and high airflow. Cooling through ventilation exemplifies a fine balance between respiratory demands and thermoregulation. To increase cooling, animals increase ventilation frequency. When birds are trying to cool off, we observe gular fluttering, which is characterized by rapid contraction and relaxation of throat muscles. Mammals pant in order to cool off. Both gular fluttering and panting have a cooling effect because rapid ventilation enhances heat loss across respiratory surfaces by convection, rapid ventilation causes evaporation of water via the tongue, and well-vascularized respiratory surfaces of mammals and birds are kept moist with secretions.
Page Ref: 663
Chapter 16 Reproductive Physiology
1) Parthenogenesis
A) enables females to self-fertilize their own ova
B) occurs in lizards, such as the Komodo dragon
C) occurs only in invertebrates
D) A and B
Answer: D
Page Ref: 668-669
2) The whiptail lizards Cnemidophorus uniparens of the American southwest are unique in that they are
A) Are an entirely female species that reproduce by parthenogenesis.
B) protogynous and the largest female develops into the male of the harem.
C) protandrous with the older, larger individuals developing into females.
D) a true social species with haploid sterile males and diploid female workers.
Answer: A
Page Ref: 669
3) The term "anisogametic" refers to
A) the haploid condition of mature gametes.
B) arrestment following the first meiotic division.
C) degradation of the polar bodies.
D) sex-specific difference in gamete size.
Answer: D
Page Ref: 670
4) One way in which gametogenesis differs between the two sexes is that in spermatogenesis,
A) the mature gametes lack mobility.
B) four viable haploid gametes are produced from one germ cell.
C) chromosome number is halved only after the second meiotic division.
D) the germ cells are diploid.
Answer: B
Page Ref: 678
5) Animals mediate the effects of steroid hormones by altering the
A) rates of hormone synthesis.
B) levels of target tissue receptors.
C) rates of degradation.
D) all of the above Answer: D Page Ref: 671
6) The immediate precursor of estradiol-17β is
A) androstenedione.
B) dihydrotestosterone.
C) progesterone.
D) testosterone.
Answer: D Page Ref: 672
7) __________ is not considered a gonadotropin.
A) CG
B) FSH
C) GnRH
D) LH
Answer: C Page Ref: 672
8) __________ is a cytochrome P450 enzyme that metabolizes androgens to estrogens.
A) Aromatase
B) Phenylethanolamine N-methyltransferase
C) Tyrosine hydroxylase
D) Steroid 22-hydroxylase
Answer: A Page Ref: 672
9) Which of the following would be considered a gonadotropin that occurs in vertebrates?
A) FSH
B) LH
C) CG
D) all of the above
Answer: D Page Ref: 672
10) The main regulator of the release of gonadotropins from the anterior pituitary is
A) aromatase.
B) GnRH.
C) CG.
D) LH.
Answer: B Page Ref: 672
11) Insects rely on the terpenoid __________ to control reproductive development, metamorphosis, and molting.
A) bombyxin
B) eclosion hormone
C) juvenile hormone
D) methyl farnesoate
Answer: C Page Ref: 673
12) Insects that develop through egg, larval, pupal, and adult stages are considered to be
A) hemimetabolous.
B) heterometabolous.
C) holometabolous.
D) hypermetabolous.
Answer: C Page Ref: 673
13) The activity levels of juvenile hormones can be reduced by
A) allatostatins.
B) allatotropins.
C) JH esterase.
D) all of the above
Answer: D Page Ref: 673
14) Methoprene
A) prevents insects from reproducing by not allowing the larvae to develop.
B) is a very effective insecticide that kills insects upon contact.
C) disrupts neural function of insects
D) is highly toxic to birds
Answer: A Page Ref: 674 (Applications 16.1)
15) Of the two types of automictic parthenogenesis, thelytoky differs in that
A) only homogametic males are produced.
B) only females are produced.
C) mitosis instead of meiosis generates diploid offspring.
D) more than one of the above
Answer: B Page Ref: 675
16) The phenomenon in which some female coral reef fish spontaneously transform into males if the dominant male is removed is known as
A) arrhenotoky.
B) protandry.
C) protogyny.
D) thelytoky.
Answer: C Page Ref: 676
17) In crocodilians and marine turtles, the sex of the young is determined by
A) homogamy vs. heterogamy.
B) aromatase activity.
C) nest temperature.
D) rates of vitellogenesis.
Answer: C Page Ref: 676
18) __________ is the reproductive strategy in which the entire development of the egg or ovum occurs externally.
A) Oviparity
B) Ovoviviparity
C) Viviparity
D) more than one of the above
Answer: A Page Ref: 677
19) Vitellogenin is a phospholipoprotein produced by the
A) follicle cells.
B) insect fat body.
C) vertebrate liver.
D) all of the above Answer: D Page Ref: 678
20) The Leydig cells of the typical vertebrate testis
A) produce testosterone.
B) develop into spermatids.
C) produce androgen-binding proteins.
D) mediate the response of the testis to FSH. Answer: A Page Ref: 681
21) The swimming capacity of human sperm is attained within the
A) bulbourethral gland.
B) epididymis.
C) prostate gland.
D) seminal vesicles.
Answer: B Page Ref: 682
22) Which of the following structures is INCORRECTLY matched to its function?
A) bulbourethral gland secretion of nutrients and enzymes
B) epididymis sperm concentration and storage
C) fallopian tube common site of fertilization
D) placenta maternal/fetal endocrine and exchange organ Answer: A Page Ref: 682
23) The alkaline fluid produced by the __________ neutralizes the acidic conditions of female reproductive tract to allow the sperm to swim.
A) bulbourethral gland
B) epididymis
C) prostate gland
D) seminal vesicles
Answer: D Page Ref: 682
24) In response to capture, animals often produce stress hormones. In green sea turtles,
A) an elevation in corticosterone levels is observed.
B) other hormones related to their reproductive condition influence the magnitude of the stress response.
C) males and females show similar increases in corticosterone levels
D) A and B
Answer: D
Page Ref: 683 (Challenges to Homeostasis 16.2)
25) The neurotransmitter __________ plays the key role in generating an erection in the mammalian penis.
A) acetylcholine
B) dopamine
C) GABA
D) nitric oxide
Answer: D
Page Ref: 685
26) Female insects possess an elaborate sperm-storage organ called the
A) accessory gland.
B) Dufour's gland.
C) gametosome.
D) spermatheca.
Answer: D
Page Ref: 686
27) Of the four extraembryonic membranes of developing amniotes, the __________ functions as a gas-exchange organ.
A) allantois
B) amnion
C) chorion
D) yolk sac
Answer: C
Page Ref: 687
28) The __________ of the amniotic egg encloses a fluid to act as a protective hydraulic cushion.
A) allantois
B) amnion
C) chorion
D) yolk sac
Answer: B
Page Ref:687
29) In the amniotic eggs of birds and reptiles, the __________ serves as a storage sac for nitrogenous wastes.
A) allantois
B) amnion
C) chorion
D) yolk sac
Answer: A Page Ref: 687
30) A member of the TGF-β family of cytokines, __________ is a peptide hormone secreted by the mature follicle.
A) CG
B) estrin
C) inhibin
D) progestin
Answer: C Page Ref: 688
31) The luteal phase of the ovulation cycle of mammals corresponds to the __________ phases of the estrous cycle.
A) proestrus and estrus
B) estrus and metestrus
C) metestrus and diestrus
D) diestrus and proestrus
Answer: C
Page Ref: 689 and Fig. 16.16
32) In the human reproductive system, ovulation is triggered
A) at the end of the luteal phase.
B) by the surge in progesterone release.
C) by the surge in LH release.
D) at the beginning of the follicular phase.
Answer: C
Page Ref: 689
33) The declining FSH levels during the follicular phase results in most of the developing follicles to undergo
A) conversion into corpora lutea.
B) degeneration by atresia.
C) development into nurse cells.
D) development into Graafian follicles.
Answer: B
Page Ref: 689
34) Driven by the __________ surge, the post-ovulation follicle undergoes a change in structure to develop into the corpus luteum.
A) FSH
B) LH
C) CG
D) progesterone
Answer: B
Page Ref: 689
35) After ovulation, the remnant of the ruptured follicle develops into the A) corpus allatum.
B) corpus luteum.
C) Graafian follicle.
D) polar bodies.
Answer: B Page Ref: 690
36) The uterine is lined by a layer of epithelial tissue known as the A) endometrium.
B) endothelium.
C) mesothelium.
D) myometrium.
Answer: A Page Ref: 691
37) The birth control pill developed in the early 1960s prevents pregnancy by
A) preventing ovulation.
B) stimulating thickening of the cervical mucus.
C) impairing endometrial growth.
D) all of the above
Answer: B Page Ref: 691
38) Parturition refers to
A) childbirth.
B) gestation.
C) menstruation.
D) placental development. Answer: A Page Ref: 691
39) The trophoblast of the implanted fertilized egg ultimately develops into the A) allantois.
B) amniotic cavity.
C) placenta.
D) zona pellucida. Answer: C Page Ref: 691-692
40) In human reproduction, once conception and successful implantation have occurred,
A) CG secreted by the placenta simulates the activity of LH.
B) the corpus luteum continues progesterone and estrogen secretion for the first trimester.
C) the placenta eventually assumes the production of progesterone and estrogen.
D) all of the above
Answer: D Page Ref: 692
41) At the onset of labor, __________ acts on the myometrium lining directly to induce contraction.
A) oxytocin
B) prolactin
C) prostaglandin
D) all of the above
Answer: D
Page Ref: 693
42) The hormone that controls milk production in mammals is
A) estrogen.
B) oxytocin.
C) prolactin.
D) prostaglandin.
Answer: C Page Ref: 693
43) The earliest mammary gland secretions, called __________, are rich in immunoprotective agents, growth factors, minerals, and vitamins.
A) caseinate
B) colostrum
C) globulus
D) meconium
Answer: B Page Ref: 695
44) Based on molecular evidence, casein most likely arose from a gene coding for
A) albumin.
B) fibrinogen.
C) myoglobin.
D) transferrin.
Answer: B Page Ref: 696
45) In addition to its effects in milk production, prolactin plays a role in
A) calcium metabolism.
B) gamma globulin biosynthesis.
C) uterine contractions.
D) maternal behavior.
Answer: D Page Ref: 693
46) __________ is a cytochrome P450 enzyme that metabolizes androgens to estrogens.
Answer: Aromatase Page Ref: 672
47) Most forms of asexual reproduction in animals occur by __________ through the use of ova and the female reproductive system.
Answer: parthenogenesis
Page Ref: 675
48) In serial hermaphroditism, __________ animals are initially males. Answer: protandrous Page Ref: 676
49) In ________________ animals, embryos obtain nourishment from yolk, and mature eggs hatch inside the mother. Answer: ovoviviparous Page Ref: 677
50) __________ is the most abundant of the yolk proteins. Answer: Vitellin Page Ref: 678
51) The __________ is the sperm-storage organ of female insects. Answer: spermatheca Page Ref: 686
52) In insects, sperm are able to fertilize the shelled egg through a tunnel called the __________. Answer: micropyle Page Ref: 680 delete, Box 14.1 not in 3e
53) Birds transfer sperm directly from the __________ of the male to that of the female. Answer: cloaca Page Ref: 684
54) Many mammals have a bone within the penis called the __________. Answer: baculum or os penis Page Ref: 685
55) The term _____________ describes the mating system where the offspring from a single litter or clutch was sired by different males. Answer: polyandry Page Ref: 686
56) In more than 100 mammalian species, embryogenesis can be arrested in the early blastocyst stage by a process known as __________. (two words) Answer: delayed implantation Page Ref: 687
57) The __________ is the loss of uterine tissue at the end of the menstrual cycle. Answer: menses Page Ref: 688
58) The lining of the uterus is known as the __________. Answer: endometrium Page Ref: 691
59) After shedding the zona pellucida, the outermost cells of the blastocyst differentiate to form the __________.
Answer: trophoblast
Page Ref: 691
60) The hormone __________ controls milk production.
Answer: prolactin
Page Ref: 695
61) The secretory units of the mammary glands are the __________.
Answer: alveoli
Page Ref: 695
62) What are the three levels through which genomic variation is generated by sexual reproduction?
Answer: First, each animal generates an enormous variety of gametes from a genome that was itself derived by a near-random combination of chromosomes from two different parents: An animal with 23 pairs of chromosomes can produce more than 8 million different gametes. Second, during meiosis, chromosomal recombinations can generate hybrids of maternal and paternal chromosomes. And third, the diploid offspring produced by fertilization are unique combinations of the variants generated by the first two processes cited above.
Page Ref: 670
63) Describe the mechanism of sex determination in the two forms of automictic parthenogenesis.
Answer: Essentially, sex determination depends on which of the sexes is homogametic. In thelytoky, the homogametic condition (XX) is female, and therefore the parthenogenetically produced offspring must also be homogametic (XX) and female. In arrhenotoky, the heterogametic (WZ) condition is female: Since fusion of the mature ovum with the second polar body simply reunites the chromatids derived from a single parent chromosome, all offspring must be homogametic (ZZ or WW) and either male (ZZ) or nonviable (WW).
Page Ref: 675
64) In most animals, the genotype of the organisms determines their sex. What is the relationship between sex determination and the environment?
Answer: Temperature-dependent sex determination (TSD) is one form of environmental sex determination that is common in reptiles: all crocodilians and sea turtles, and in some species of lizards and terrestrial turtles. At the pivotal temperature (intermediate ambient temperature), equal numbers of male and female offspring are produced. Three patterns have been observed from studies of TSD: 1) In some species of turtles, female offspring are produced above the pivotal temperature while males are produced below; 2) some species of lizards produce males when the temperatures are high and females when temperatures are low; and 3) in crocodiles and alligators, larger numbers of female offspring are produced at both low and high temperatures, while the abundance of male offspring is higher at intermediate temperatures.
Page Ref: 676
65) What role does inhibin play in regulating ovulation?
Answer: Inhibin is released by the mature ovarian follicle (or corpus luteum) and operates via the hypothalamus-pituitary axis to inhibit the synthesis and release of FSH. Inhibin also has autocrine and paracrine effects at the level of the ovary to inhibit estrogen synthesis.
Page Ref: 688-689
66) Describe the interactive roles of the various hormones in the process of parturition.
Answer: During gestation, high estrogen titers enhance the contractile strength of the uterine smooth muscles as well as their expression of oxytocin receptors, while progesterone inhibits uterine contractions. At the end of gestation when progesterone levels decline, the muscles are freed from inhibition. Fetal cells produce oxytocin, which stimulates the release of contraction-stimulating prostaglandins. Simultaneously, the maternal posterior pituitary begins secreting oxytocin that collectively with the prostaglandins stimulate uterine smooth muscle contractions. The stress stimulates the release of additional oxytocin and prostaglandins, thereby engaging a positive feedback loop.
Page Ref: –692-693
67) What is the proposed relationship between fibrinogen and casein?
Answer: Casein or milk protein is thought to have been derived from the gene coding for thechain of fibrinogen. Evidence to support this hypothesis comes from sequence similarities between the two proteins (and genes) and well as from the observation that primitive mammary glands produce a milk primarily derived from presynthesized components of the blood, including fibrinogen.
Page Ref: 696-697
68) What role does prolactin play in reproductive behavior?
Answer: During pregnancy in mammals, prolactin and the steroid hormones alter the brain biochemistry of the female to promote maternal behavior. The behavior is related to increased prolactin synthesis and to the expression of prolactin receptors in the medial peroptic area of the hypothalamus: The hypothalamus exhibits greater sensitivity to prolactin. In mammals in which paternal care has been observed, males also have higher levels of prolactin.
Page Ref: 693-694
69) What is the relationship between glucocorticoids and testosterone in the reproductive behavior of frogs?
Answer: Calling, mediated by testosterone, is one of the most energetically costly behaviors observed in ectotherms, necessitating the mobilization of energy stores by glucocorticoids. Elevated levels of testosterone result in more calling, increasing the demand for energy and the titers of glucocorticoids. Ultimately, the glucocorticoid levels are so high that the stress response is elicited, testosterone production declines, and calling ceases.
Page Ref: 683
70) All mammals have mammary glands and produce milk. Discuss the features of mammary glands that all mammals have in common, and describe the differences in the anatomical structure of mammary glands in the three different groups of mammals (monotremes, marsupials, and eutherians).
Answer: In all mammals, mammary glands consist of exocrine glands, which secrete milk and myoepithelial cells that have control over the secretions. Mammary glands are similar to sebaceous glands in that they are associated with hair follicles. Milk is released from exocrine glands, milk’s composition includes macromolecules and fluids, and prolactin controls milk production. Mammary glands of monotremes consist of convoluted tubes that lie under the skin of the female on the ventral side. Monotremes have no nipples, so the milk oozes through the ducts onto the female’s fur and the pups lap up the milk Marsupials have mammary glands with teats. A newborn marsupial takes the teat into its mouth; the teat enlarges in its mouth and keeps the newborn in position. The mammary glands of eutherian mammals consist of globes grouped into alveoli and the alveoli have ducts, which lead to an external teat. Whenever young eutherian mammals are hungry, they locate the teat, suck the milk, and release the teat upon satiation or when the mom walks away.
Page Ref: 695
