Since you did not give a list of choices,here are some reasons why l<span>iving cells cannot use heat to provide the activation energy for biochemical reactions:
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>Heat can never be used to do work.
>Heat is not readily available to all living cells.
>Heat doesn't provide the activation energy for their reactions.
If they live in a river, they would most likely need fins (to swim) and gills (to breathe under water)
Hope this helps!
Power is the rate at which work is done.
Hope this helps!