Which one of the following electron acceptor is present in respiratory chain

Options

A. Cytochrome f
B. Cytochrome `a_(3)`
C. Plastocyanin
D. Ferredoxin.

Answer

To solve the question "Which one of the following electron acceptors is present in the respiratory chain?", we will analyze each of the given options one by one.

### Step-by-Step Solution:

1. **Understanding the Respiratory Chain**: The respiratory chain, also known as the electron transport chain, is a series of complexes located in the inner mitochondrial membrane. It is responsible for transferring electrons from electron donors to electron acceptors through a series of redox reactions, ultimately leading to the production of ATP.

2. **Evaluating Option A: Cytochrome F**:
- Cytochrome F is involved in photosynthesis, specifically in transferring electrons from reduced quinone to plastocyanin in plants.
- Since it is part of the photosynthetic process, it is **not** involved in the respiratory chain.
- **Conclusion**: Incorrect option.

3. **Evaluating Option B: Cytochrome A3**:
- Cytochrome A3 is a component of complex IV of the mitochondrial respiratory chain.
- It plays a crucial role in transferring electrons to the terminal electron acceptor, which is oxygen.
- Since it is directly involved in the respiratory chain, this option is **correct**.
- **Conclusion**: Correct option.

4. **Evaluating Option C: Plastocyanin**:
- Plastocyanin is a soluble electron carrier that transfers electrons between the two photosystems during photosynthesis in plants.
- As it is associated with photosynthesis, it is **not** part of the respiratory chain.
- **Conclusion**: Incorrect option.

5. **Evaluating Option D: Ferredoxin**:
- Ferredoxin is another electron carrier involved in photosynthesis, specifically in transferring electrons from P700 (a photosystem) to NADP.
- Like the previous options, it is also **not** part of the respiratory chain.
- **Conclusion**: Incorrect option.

### Final Answer:
The correct electron acceptor present in the respiratory chain is **Cytochrome A3** (Option B).

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