Which molecules provide energy and reducing power for the Calvin cycle to convert CO2 into sugars?

Which molecules provide energy and reducing power for the Calvin cycle to convert CO2 into sugars?

• A. ATP and NADPH
• B. ATP and NADH
• C. NADPH and FAD
• D. ATP and FADH2

Answer: (A)

The Calvin cycle runs on energy from ATP and reducing power from NADPH, both supplied by the light-dependent reactions. ATP provides the chemical energy to drive the phosphorylation steps that convert intermediates into higher-energy forms, while NADPH donates electrons to reduce intermediate molecules (such as 3-phosphoglycerate) toward glyceraldehyde-3-phosphate and ultimately toward sugars. This combination of ATP and NADPH is produced in the chloroplasts during photosynthesis, not by NADH or FAD-based pathways used in respiration. That’s why ATP together with NADPH best fits the role of energy and reducing power for turning CO2 into sugars.

The Calvin cycle runs on energy from ATP and reducing power from NADPH, both supplied by the light-dependent reactions. ATP provides the chemical energy to drive the phosphorylation steps that convert intermediates into higher-energy forms, while NADPH donates electrons to reduce intermediate molecules (such as 3-phosphoglycerate) toward glyceraldehyde-3-phosphate and ultimately toward sugars. This combination of ATP and NADPH is produced in the chloroplasts during photosynthesis, not by NADH or FAD-based pathways used in respiration. That’s why ATP together with NADPH best fits the role of energy and reducing power for turning CO2 into sugars.