The Calvin cycle uses six ATP molecules to produce one three-carbon sugar (glyceraldehyde-3-phosphate, 3GP) from three molecules of RuBP and three molecules of carbon dioxide. Yet the Calvin cycle actually requires nine ATP molecules to function. Why?
a) Three additional ATP molecules are used to reduce NADP+ to NADPH.
b) Three additional ATP molecules are used to phosphorylate carbon dioxide for the next cycle.
c) Three additional ATP molecules are hydrolyzed to keep enough heat available for the reaction to continue.
d) Three additional ATP molecules are used to regenerate RuBP.Three additional ATP molecules are used to reduce NADP+ to NADPH.