Which statement regarding the light reactions of photosynthesis is true?

• A. Oxygen is consumed during the light reactions.
• B. Glucose is synthesized directly during the light reactions.
• C. ATP and NADPH are produced during the light reactions.
• D. The light reactions occur in the stroma of the chloroplast.

Answer: (C)

Verified step by step guidance

1. Step 1: Begin by understanding the light reactions of photosynthesis. These reactions occur in the thylakoid membranes of the chloroplast and are responsible for converting light energy into chemical energy in the form of ATP and NADPH.
2. Step 2: Clarify that oxygen is not consumed during the light reactions. Instead, oxygen is produced as a byproduct when water molecules are split (a process called photolysis) to provide electrons for the photosystem.
3. Step 3: Note that glucose is not synthesized directly during the light reactions. Glucose synthesis occurs during the Calvin cycle, which uses ATP and NADPH produced in the light reactions to fix carbon dioxide into sugars.
4. Step 4: Confirm that ATP and NADPH are indeed produced during the light reactions. ATP is generated through photophosphorylation, and NADPH is formed when electrons are transferred to NADP⁺ at the end of the electron transport chain.
5. Step 5: Correct the statement about the location of the light reactions. They occur in the thylakoid membranes, not the stroma. The stroma is the site of the Calvin cycle, which follows the light reactions.