In PS II, first known electron acceptor is

Options

A. Cytochrome
B. PQ
C. FAS
D. Pheophytin

Answer

### Step-by-Step Solution:

1. **Understanding Photosystem II (PS II)**:
- Photosystem II is one of the two photosystems involved in the process of photosynthesis. It is primarily responsible for the light-dependent reactions.

2. **Location of PS II**:
- PS II is located in the thylakoid membrane of chloroplasts, where it plays a crucial role in capturing light energy.

3. **Function of PS II**:
- When light is absorbed by PS II, it leads to the photolysis of water, which splits water molecules into oxygen, protons, and electrons.

4. **Electron Generation**:
- The absorbed light energy excites electrons in the chlorophyll (specifically in the P680 reaction center of PS II), generating high-energy electrons.

5. **Electron Transport Chain**:
- The excited electrons are transferred through a series of electron carriers. The first known electron acceptor in this chain is crucial for understanding the process.

6. **Identifying the First Electron Acceptor**:
- The first known electron acceptor in PS II is **pheophytin** (often abbreviated as pH). This molecule accepts the high-energy electrons generated from the photolysis of water.

7. **Subsequent Electron Carriers**:
- After pheophytin, the electrons are passed on to other components in the electron transport chain, including QA, QB, cytochrome b6f, and plastocyanin (PC).

8. **Conclusion**:
- Therefore, the correct answer to the question "In PS II, the first known electron acceptor is" is **pheophytin**.

### Final Answer:
The first known electron acceptor in PS II is **pheophytin**.

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