Select the correct statement .

Options

A. FAD is hydrogen acceptor when succinic acid is oxidized to malic acid .
B. Oxygen acts a terminal electron acceptor in aerobic respiration .
C. Cytochrome c and `a_3` contains two copper centres .
D. Respiration is a catabolic process only .

Answer

To solve the question "Select the correct statement", we will analyze each option provided and determine which one is accurate based on our understanding of biological processes, particularly in the context of cellular respiration.

### Step-by-step Solution:

1. **Analyze Option 1**:
- The statement claims that "FAD is a hydrogen acceptor when succinic acid is oxidized to malic acid."
- In the Krebs cycle, succinic acid is actually converted to fumaric acid, not malic acid. During this conversion, FAD acts as an electron acceptor and gets reduced to FADH2. Therefore, this option is incorrect.

2. **Analyze Option 2**:
- The statement claims that "oxygen acts as a terminal electron acceptor in aerobic respiration."
- In the electron transport chain (ETC), oxygen indeed acts as the final electron acceptor. Electrons are transferred through various complexes, and ultimately, they are transferred to oxygen, which combines with protons to form water. This statement is correct.

3. **Analyze Option 3**:
- The statement claims that "cytochrome C and A3 contain two copper centers."
- Cytochrome C does not contain copper centers; it is a heme-containing protein. However, cytochrome A and A3, which are part of complex IV, do contain copper centers. Therefore, this statement is incorrect.

4. **Analyze Option 4**:
- The statement claims that "respiration is a catabolic process only."
- Respiration is not solely a catabolic process; it is considered an amphibolic pathway because it involves both catabolic and anabolic reactions. Thus, this statement is also incorrect.

### Conclusion:
After analyzing all the options, the correct statement is **Option 2: Oxygen acts as a terminal electron acceptor in aerobic respiration.**

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