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In a chloroplast, the highest number of protons is found in the
Your answer:
Correct answer: (d)
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Explanation
Why (d) is correct
Protons build up inside the thylakoid lumen. They come from the splitting of water on the lumen side and are also pumped in as electrons move through the cytochrome complex. NADP reductase removes protons from the stroma, so the lumen has the most protons.
Why the other options are wrong
- (a) · your answer The stroma loses protons (they are pumped into the lumen and used to make NADPH), so its proton concentration is lower.
- (b) · your answer The space between the two envelope membranes does not collect the protons of photosynthesis.
- (c) · your answer The antenna complex is a group of pigment molecules, not a compartment where protons collect.
NCERT point: The proton gradient across the thylakoid membrane (high in the lumen) drives ATP synthesis through ATP synthase.
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