What is the role of NADP⁺ in photosynthesis?

• A. It helps produce ATP from the light reactions.
• B. It absorbs light energy.
• C. It forms part of photosystem II.
• D. It is the primary electron acceptor.
• E. It forms NADPH to be used in the Calvin cycle.

Answer: (E)

Verified step by step guidance

1. Understand the context of photosynthesis: Photosynthesis is a process used by plants, algae, and some bacteria to convert light energy into chemical energy stored in glucose. It consists of two main stages: the light-dependent reactions and the Calvin cycle (light-independent reactions).
2. Identify the role of NADP+ in the light-dependent reactions: During these reactions, which occur in the thylakoid membranes of chloroplasts, light energy is used to produce ATP and NADPH. NADP+ acts as an electron carrier.
3. Explain the electron transport chain: In the light-dependent reactions, water molecules are split, releasing electrons, protons, and oxygen. The electrons are transferred through a series of proteins in the thylakoid membrane, known as the electron transport chain.
4. Describe the reduction of NADP+: As electrons move through the electron transport chain, they eventually reach NADP+, which acts as the final electron acceptor. NADP+ is reduced to form NADPH by gaining electrons and a proton (H+).
5. Connect NADPH to the Calvin cycle: NADPH, along with ATP produced in the light-dependent reactions, is then used in the Calvin cycle to convert carbon dioxide into glucose. Thus, NADP+ is crucial for forming NADPH, which provides the reducing power needed for the synthesis of carbohydrates in the Calvin cycle.