Which of the following explains why elements, such as carbon and oxygen, that are used in organic molecules are not permanently removed from the environment?
A. They are replenished by sunlight.
B. They are cycled through ecosystems.
C. They are replaced by volcanic eruptions.
D. They are produced constantly from nutrients.

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Answers

2014-06-18T09:35:50+08:00
B. They are cycled through ecosystems. 


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