Given a scientific question, generate a correct answer to it.

Q: A problem with using food chains to describe ecosystems is that some organisms can feed on or be consumed by species from more than one of what level?

A: trophic level
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Q: What third property is different if two boxes have the same volume but one has greater mass?

A: density
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Q: Both endotherms and ectotherms control what through behavioral responses to changes in the environment?

A:
body temperature
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