Which of the following statements about RuBisCO is true?
It is an enzyme involved in the photolysis of water.
It catalyzes the carboxylation of RuBP.
It is active only in the dark.
It has higher affinity for oxygen than carbon dioxide.
RuBisCO (Ribulose bisphosphate carboxylase-oxygenase) catalyses the most crucial step of the Calvin cycle: the carboxylation of Ribulose bisphosphate (RuBP) . Regarding the incorrect options: RuBisCO has a much greater affinity for CO2 than for O2 when the CO2:O2 ratio is nearly equal ; photolysis of water is associated with Photosystem II, not RuBisCO ; and the biosynthetic phase (Calvin cycle) is dependent on the products of light reactions (ATP and NADPH), meaning it does not strictly occur 'only in the dark' .
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