The ratio of ATP to NADPH used by the Calvin cycle is approximately 3:2 (3 molar ATP used for each 2 molar NADPH). What is the MINIMUM number of these molecules required to synthesize one mole of glucose?
A)30 molar ATP + 20 molar NADPH
B)18 molar ATP + 12 molar NADPH
C)12 molar ATP + 8 molar NADPH
D)6 molar ATP + 4 molar NADPH
E)3 molar ATP + 2 molar NADPH

Question

Quizplus · Accepted Answer

The Calvin cycle requires 6 molecules of CO2 to synthesize one molecule of glucose. For each CO2 molecule fixed, the cycle uses 9 ATP and 6 NADPH molecules. Therefore, to fix 6 CO2 molecules, the cycle would need 54 ATP and 36 NADPH molecules. To simplify this, we can divide each by the lowest common denominator, which is 18. This gives us 3 molar ATP and 2 molar NADPH used for each CO2 fixed. Therefore, to synthesize one mole of glucose, the cycle needs 18 molar ATP and 12 molar NADPH. Choice B is the closest option.

The Ratio of ATP to NADPH Used by the Calvin