Question

How many molecules of ATP and NADPH are required for every molecule of CO₂ fixed in the Calvin cycle?

• A. 2 molecules of ATP and 3 molecules of NADPH
• B. 2 molecules of ATP and 2 molecules of NADPH
• C. 3 molecules of ATP and 3 molecules of NADPH
• D. 3 molecules of ATP and 2 molecules of NADPH

Answer 1

The Correct Option is D

The Calvin Cycle: Carbon Fixation and Glucose Production 

The Calvin cycle involves the fixation of carbon dioxide and the production of glucose.

For every molecule of CO₂ fixed, the following are required:

• 3 molecules of ATP are used to power the cycle.
• 2 molecules of NADPH are used in the reduction phase to reduce 3-phosphoglycerate into glyceraldehyde-3-phosphate (G3P).

Thus, for every CO₂ fixed, 3 molecules of ATP and 2 molecules of NADPH are required.