The reactions of the Calvin cycle used to be referred to as the "dark reactions" of photosynthesis, implying that light was not required for this pathway to incorporate CO₂ into carbohydrate. However, in the absence of light the Calvin cycle shuts down. Which of the following parts of the Calvin cycle would be impacted FIRST by the absence of light energy? A)the reduction of 3-phosphoglycerate and the regeneration of RuBP B)the carboxylation of RuBP and the reduction of 3-phosphoglycerate C)the carboxylation of RuBP and the regeneration of RuBP D)the carboxylation of RuBP and the synthesis of hexose sugars

Question

Quizplus · Accepted Answer

The reduction of 3-phosphoglycerate and the regeneration of RuBP in the Calvin cycle are directly dependent on ATP and NADPH, which are products of the light-dependent reactions. Without light, these energy carriers are not replenished, impacting these steps first.

The Reactions of the Calvin Cycle Used to Be Referred