What are the main reactants and products of the Calvin cycle?

What are the main reactants and products of the Calvin cycle?

• A. Reactants: CO2, ATP, NADPH; Products: G3P, ADP, NADP+, Pi.
• B. Reactants: O2, ATP; Products: CO2.
• C. Reactants: H2O, NADPH; Products: O2, ATP.
• D. Reactants: G3P; Products: RuBP and CO2.

Answer: (A)

The Calvin cycle uses carbon dioxide and the energy-rich molecules from the light reactions, ATP and NADPH, to convert inorganic carbon into an organic sugar precursor. Specifically, CO2 is fixed and reduced with the help of ATP and NADPH, producing G3P, a three-carbon sugar. This G3P can be used to make glucose later, while the rest of the cycle regenerates the RuBP acceptor to keep the process going. The ATP and NADPH are consumed and become ADP, NADP+, and Pi, which feed back into the light reactions. That makes the combination of inputs and outputs in the correct option: CO2, ATP, and NADPH as reactants, and G3P with ADP, NADP+, and Pi as products. The other options mix in incorrect reactants or products—oxygen, water, or CO2 being produced instead of consumed—so they don’t fit the actual process of the Calvin cycle.

The Calvin cycle uses carbon dioxide and the energy-rich molecules from the light reactions, ATP and NADPH, to convert inorganic carbon into an organic sugar precursor. Specifically, CO2 is fixed and reduced with the help of ATP and NADPH, producing G3P, a three-carbon sugar. This G3P can be used to make glucose later, while the rest of the cycle regenerates the RuBP acceptor to keep the process going. The ATP and NADPH are consumed and become ADP, NADP+, and Pi, which feed back into the light reactions.

That makes the combination of inputs and outputs in the correct option: CO2, ATP, and NADPH as reactants, and G3P with ADP, NADP+, and Pi as products. The other options mix in incorrect reactants or products—oxygen, water, or CO2 being produced instead of consumed—so they don’t fit the actual process of the Calvin cycle.