In photosystem-I the first electron acceptor is

Options

A. Plastocyanin
B. An iron-sulphur protein
C. Ferredoxin
D. Cytochrome

Answer

To answer the question about the first electron acceptor in Photosystem I, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Photosystem I**:
- Photosystem I (PSI) is one of the two photosystems involved in the light-dependent reactions of photosynthesis. It absorbs light and initiates the process of electron transport.

2. **Identifying Electron Acceptors**:
- In the context of PSI, various proteins can act as electron acceptors. The key players include plastocyanin, ferredoxin, and iron-sulfur proteins.

3. **Electron Transfer Process**:
- When light energy is absorbed by PSI, it energizes electrons, which are then transferred to the first electron acceptor.

4. **First Electron Acceptor**:
- The first electron acceptor in Photosystem I is **ferredoxin (FD)**. This is a type of iron-sulfur protein that plays a crucial role in the electron transport chain.

5. **Confirmation of the Answer**:
- While plastocyanin and iron-sulfur proteins are involved in the electron transport chain, ferredoxin is specifically the first acceptor that captures the energized electrons from PSI.

6. **Conclusion**:
- Therefore, the correct answer to the question is **ferredoxin**.