KEY TAKEAWAYS •
There are certain qualities of living things that separate them from nonliving things.
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There is a hierarchy of life that starts with subatomic particles as the smallest part and that ends with the biosphere, which represents all ecosystems put together.
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Life on earth is carbon-based so that living things (and many nonliving things) are made with this atom.
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There are four major organic macromolecules, such as proteins, carbohydrates, lipids, and nucleic acids.
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Water is essential for life and has molecular characteristics that make it an excellent solvent and temperature-regulator. It also participates in the pH of solutions that is strictly regulated in living systems for the purpose of enzymes and enzymatic reactions.
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