During night, desert plants<span> absorb carbon dioxide and form an intermediate. Then during day time when the stomata is closed to prevent loss of water, they use this stored carbon dioxide to perform </span>photosynthesis<span>.</span>
Function of an enzyme is to lower reaction's activation energy and to increase speed of a reaction, but to make it happen, enzyme and substrate must fit spatially. The shape of an enzyme is essential to make enzyme-substrate complex - if active site of an enzyme doesn't fit to substrate, there won't be a enzyme-catalised reaction.
I think it might be lyosomes as they help break down waste and other stuff in a cell.
I believe proteins would be the correct answer, but of course I just learnt this stuff 2 weeks ago. xD