Which of the following ETS complex is inhibited by cyanide?

Options

A. Complex II
B. Complex V
C. Complex IV
D. Complex III

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks which complex of the Electron Transport System (ETS) is inhibited by cyanide.

2. **Identifying the Complexes**: The Electron Transport System consists of several complexes:
- Complex I
- Complex II
- Complex III
- Complex IV
- Complex V

3. **Analyzing Inhibitors**:
- Complex II is inhibited by oxaloacetate.
- Complex V is inhibited by IF1.
- Complex III is inhibited by antimycin A.
- Complex IV is the focus of our question.

4. **Cyanide's Role**: Cyanide is known to specifically inhibit Complex IV of the Electron Transport Chain. It does this by binding to the cytochrome c oxidase, which is part of Complex IV, preventing the transfer of electrons to oxygen.

5. **Conclusion**: Based on the information, the correct answer to the question is Complex IV, as it is the complex inhibited by cyanide.

**Final Answer**: Complex IV

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