Answer:
Humans release carbon dioxide (CO2) into the atmosphere through cellular respiration. This CO2 is used by plants during photosynthesis. During photosynthesis, plants release oxygen (O2) into the atmosphere. The oxygen is used by animals in order to carry out cellular respiration.
Explanation:
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Answer:
The fish did not yet exist when the old layers of rocks were deposited. In fact, animals with hard parts did not evolve until about 600 million years ago, which is only about 13% of the 4.5 billion year age of the Earth. Multicellular animals without hard parts left tracks in older sediments, but had no fossilize-able body parts.
Explanation:
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