Last electron acceptor of PS I is

Options

A. Ferredoxin
B. Cyt `b_(6)`
C. Plastocyanin
D. Plastoquinone.

Answer

**Step-by-Step Solution:**

1. **Understanding Photosystems**: Photosynthesis involves two main photosystems, PS I (Photosystem I) and PS II (Photosystem II). Each photosystem has a specific role in the light-dependent reactions of photosynthesis.

2. **Electron Excitation**: When light energy is absorbed by chlorophyll in PS II, it excites electrons, which are then transferred through a series of proteins in the electron transport chain.

3. **Electron Transfer from PS II to PS I**: The electrons from PS II are transferred to a protein complex called cytochrome b6f, and then to plastocyanin, which carries the electrons to PS I.

4. **Electron Excitation in PS I**: In PS I, the absorbed light energy excites the electrons again, and these high-energy electrons are transferred to a final electron acceptor.

5. **Identifying the Last Electron Acceptor**: The last electron acceptor in PS I is ferredoxin. It receives the electrons and subsequently helps in the reduction of NADP+ to form NADPH.

6. **Conclusion**: Therefore, the last electron acceptor of PS I is ferredoxin.

**Final Answer**: The last electron acceptor of PS I is ferredoxin.

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