Given scientific fact as input, generate the question from this fact such that it can be answered from the input.

Q: Metabolism produces waste energy in the form of heat, which helps warm-blooded (endotherm) animals conserve and maintain heat at a relatively constant body temperature.

A: Metabolism produces waste energy in the form of heat, which helps what type of animal conserve and maintain heat at a relatively constant body temperature?
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Q: Energy do ecosystems absorb on the earth.

A: What do ecosystems absorb on the earth?
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Q: Cholesterol type of molecules help the plasma membrane keep its shape.

A:
What type of molecules help the plasma membrane keep its shape?
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