What is the role of ATP in photosynthesis?

• A. Provides or stores energy
• B. Reduces CO2
• C. For dark stage
• D. Glucose formation

Answer: (A)

ATP provides or stores energy. In photosynthesis, energy from light is captured to make ATP, which then acts as the energy currency in the light-independent reactions (the Calvin cycle). The steps that build sugars require energy input, such as the phosphorylation of intermediates and the regeneration of RuBP, and these energy needs are supplied by ATP. It’s important to note that ATP is not a reducing agent—NADPH supplies the electrons to reduce CO2 during carbon fixation. The idea of a “dark stage” is outdated; the Calvin cycle can run when ATP and NADPH are available from the light reactions, so ATP’s role is to power the energy-demanding transformations that convert CO2 into organic sugars. glucose formation is the overall outcome of multiple steps, powered by ATP and NADPH, not a direct action of ATP alone.