Question

Which of the following statements is incorrect

• A. Oxidation-reduction reactions produce proton gradient in respiration
• B. During aerobic respiration, role of oxygen is limited to the terminal stage
• C. In ETC (Electron Transport Chain), one molecule of NADH+H⁺ gives rise to 2 ATP molecules, and one FADH₂ gives rise to 3 ATP molecules
• D. ATP is synthesized through complex V

Answer 1

The Correct Option is C

To determine which statement is incorrect, let's examine the provided options one by one:

1. Oxidation-reduction reactions produce proton gradient in respiration: This statement is correct. In cellular respiration, oxidation-reduction (redox) reactions within the Electron Transport Chain (ETC) lead to the pumping of protons (H⁺) across the inner mitochondrial membrane, creating a proton gradient. This proton gradient is essential for ATP synthesis during oxidative phosphorylation.
2. During aerobic respiration, the role of oxygen is limited to the terminal stage: This statement is correct. In aerobic respiration, oxygen acts as the final electron acceptor at the end of the ETC. It combines with electrons and protons to form water, completing the process of cellular respiration.
3. In ETC (Electron Transport Chain), one molecule of NADH+H⁺ gives rise to 2 ATP molecules, and one FADH₂ gives rise to 3 ATP molecules: This statement is incorrect. The standard biochemical perspective states that one molecule of NADH typically yields approximately 2.5 to 3 ATP molecules, while one FADH₂ yields approximately 1.5 to 2 ATP molecules. Therefore, the values in this statement are incorrect.
4. ATP is synthesized through complex V: This statement is correct. Complex V, also known as ATP synthase, is the enzyme responsible for synthesizing ATP as protons flow back through it, driven by the proton gradient established during earlier stages of the ETC.

Based on these analyses, the incorrect statement is: "In ETC (Electron Transport Chain), one molecule of NADH+H⁺ gives rise to 2 ATP molecules, and one FADH₂ gives rise to 3 ATP molecules." The expected ATP yield is different as described.