You learned in Chapter 2 that living things are composed of the same elements as the inanimate universe (e.g., C, H, O, P, N, and S). But usually the arrangements of these atoms into molecules are unique in biological systems. You will not find biological molecules such as proteins in nonliving matter unless they came from a once-
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Experimental evidence was used to refute the idea that life could arise from nonliving materials.
Water did not always exist on Earth, and its presence on Earth was necessary before life could arise.
Experimental evidence supports the theory that life evolved as the result of chemical and physical changes on early Earth.
Evidence discovered in meteorites and on Mars raises questions about whether life evolved on bodies other than Earth.