During photosynthesis, ATP synthesis takes place when electrons move from:
Correct answer: C. Cytochrome to Plastocyanin (Pc)
- A. Primary Electron Acceptor (PEA) to Plastoquinone (Pq)
- B. Plastoquinone (Pq) to cytochromes
- C. Cytochrome to Plastocyanin (Pc)
- D. Plastocyanin (Pc) to Photosystem I (PS I)
Explanation
When an electron leaves PSII, it is transferred first to a small organic molecule (plastoquinone, Pq), then to a cytochrome complex (Cyt), and finally to a copper-containing protein called plastocyanin (Pc). As the electron moves through this electron transport chain, it goes from a higher to a lower energy level, releasing energy. Some of the energy is used to pump protons H+ from the stroma (outside of the thylakoid) into the thylakoid interior.This transfer of H+, along with the release of H+ from the splitting of water, forms a proton gradient that will be used to make ATP.
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