Which stage uses ATP and NADPH to synthesize sugars from carbon dioxide and occurs in the stroma?

• A. Light-dependent reactions
• B. Light-independent reactions
• C. Photosystems
• D. ATP Synthase

Answer: (B)

Calvin cycle. This stage uses ATP and NADPH produced by the light-dependent reactions to fix carbon dioxide into sugars, and it takes place in the stroma of the chloroplast. In this cycle, CO2 is incorporated into a five-carbon sugar, then converted through a series of steps that require ATP for energy and NADPH for reducing power, ultimately forming glyceraldehyde-3-phosphate and regenerating the CO2-accepting molecule to keep the cycle going. The reason this is the stage that fits is that it directly uses the energy carriers from the light reactions to build sugars, and it operates in the stroma, unlike the light-dependent reactions, which occur in the thylakoid membranes.