Ques:Q: Living things get energy from food in a process called respiration, which releases what gas back into the atmosphere? Choices: - oxygen - hydrogen - nitrogen - carbon dioxide A:

Ans:carbon dioxide
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Ques:Q: Nitrogen is a very important element to living things, because it is part of nucleotides and amino acids that are the building blocks of nucleic acids and these? Choices: - cells - lipids - follicles - proteins A:

Ans:proteins
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Ques:Q: What are a class of biochemical compounds that living things use to store energy? Choices: - hydrocarbons - proteins - calories - lipids A:

Ans:lipids
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Ques:Q: How many protons do all atoms of a particular element have in their nuclei? Choices: - varying number - three - zero - same number A:

Ans:
same number
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