What is the electron transport chain's final electron acceptor in aerobic respiration, and what is produced to drive ATP synthesis?

What is the electron transport chain's final electron acceptor in aerobic respiration, and what is produced to drive ATP synthesis?

• A. Glucose; produced ATP directly
• B. Oxygen; it accepts electrons and forms water, driving proton motive force that powers ATP synthase
• C. Nitrogen; forms ammonia
• D. Sulfur; forms hydrogen sulfide

Answer: (B)

Oxygen is the final electron acceptor in the electron transport chain during aerobic respiration. It accepts electrons at the end of the chain and combines with protons to form water. The passage of electrons to oxygen releases energy that pumps protons across the inner mitochondrial membrane, creating a proton gradient (proton motive force). This gradient drives ATP synthase, which converts ADP and inorganic phosphate into ATP as protons flow back through the enzyme. Glucose is the fuel oxidized earlier, not the final electron acceptor; nitrogen and sulfur can serve as electron acceptors in some anaerobic contexts, but not in aerobic respiration where oxygen is present.

Oxygen is the final electron acceptor in the electron transport chain during aerobic respiration. It accepts electrons at the end of the chain and combines with protons to form water. The passage of electrons to oxygen releases energy that pumps protons across the inner mitochondrial membrane, creating a proton gradient (proton motive force). This gradient drives ATP synthase, which converts ADP and inorganic phosphate into ATP as protons flow back through the enzyme. Glucose is the fuel oxidized earlier, not the final electron acceptor; nitrogen and sulfur can serve as electron acceptors in some anaerobic contexts, but not in aerobic respiration where oxygen is present.