Name the two types of particle transferred from NADPH to CO2 in the dark stage of photosynthesis.

Name the two types of particle transferred from NADPH to CO2 in the dark stage of photosynthesis.

• A. Oxygen and Carbon
• B. Water and Oxygen
• C. Electrons and Protons
• D. Protons Only

Answer: (C)

In the dark (Calvin cycle) reactions, CO2 is reduced using reducing power from NADPH. NADPH donates the reducing equivalents needed to build carbohydrate by transferring electrons and a hydrogen ion to the carbon skeleton. So the two particles moved from NADPH to CO2 intermediates are electrons and protons. (NADPH carries a hydride, delivering two electrons and a proton to the substrate, with another proton often coming from the medium to balance the reaction.) This reducing power, together with ATP, drives the conversion of CO2 into sugars.

In the dark (Calvin cycle) reactions, CO2 is reduced using reducing power from NADPH. NADPH donates the reducing equivalents needed to build carbohydrate by transferring electrons and a hydrogen ion to the carbon skeleton. So the two particles moved from NADPH to CO2 intermediates are electrons and protons. (NADPH carries a hydride, delivering two electrons and a proton to the substrate, with another proton often coming from the medium to balance the reaction.) This reducing power, together with ATP, drives the conversion of CO2 into sugars.