What is the primary electron donor whose photolysis produces molecular oxygen during light reactions of photosynthesis?
Answer and explanation
Correct answer: D. Water (H2O)
- Step 1: In Photosystem II (PS II), the oxygen-evolving complex contains a manganese cluster. Step 2. Light-driven oxidation splits water: 2 H2O -> 4 H+ + 4 e- + O2, supplying electrons to replace those excited in P680. Answer: Water (H2O). Why not the others: CO2 is the carbon source in dark reactions; glucose is the end product; NADPH is an electron carrier generated by PS I.
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