Which species from the light reactions keeps thioredoxin reduced so that it can activate enzymes in the Calvin cycle?
A) ferredoxin
B) plastoquinone
C) P700
D) NADPH

Question

Quizplus · Accepted Answer

Ferredoxin is the species from the light reactions that keeps thioredoxin reduced so that it can activate enzymes in the Calvin cycle. Thioredoxin is reduced by ferredoxin-dependent thioredoxin reductase, which uses electrons passed from ferredoxin to NADP+. Reduced thioredoxin then activates enzymes in the Calvin cycle, including ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco), the key enzyme that catalyzes carbon fixation. Plastoquinone is involved in the electron transport chain between photosystem II and photosystem I. P700 is the reaction center chlorophyll in photosystem I. NADPH is a product of the light reactions and is used to reduce carbon dioxide in the Calvin cycle.

Which Species from the Light Reactions Keeps Thioredoxin Reduced So