MCAT Biochemistry Question 149: Answer and Explanation
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Question: 149
14. Which complex does not contribute to the proton-motive force?
- A. Complex I
- B. Complex II
- C. Complex III
- D. Complex IV
Correct Answer: B
Explanation:
Complex II is the only complex of the ETC that does not contribute to the proton gradient. Complexes I and III each add four protons to the gradient; Complex IV adds two protons to the gradient.