Answer: Act as the final electron acceptor at the end of the electron transport chain.
- A Activate the enzyme hexokinase to begin glucose breakdown under most conditions studied
- B Provide carbon atoms that are incorporated into ATP in standard reference material
- C Act as the final electron acceptor at the end of the electron transport chain
- D Directly combine with glucose in the cytoplasm during glycolysis as widely reported
Correct answer: C. Act as the final electron acceptor at the end of the electron transport chain
Explanation: In aerobic respiration, oxygen serves as the final electron acceptor of the electron transport chain, combining with electrons and protons to form water, allowing the chain to continue functioning.
Aerobic respiration unfolds in three locations: glycolysis in the cytoplasm yields a small amount of ATP directly, the Krebs cycle in the mitochondrial matrix harvests electron carriers (NADH, FADH2), and the electron transport chain in the inner mitochondrial membrane uses those carriers to generate the bulk of the ATP, with O2 needed only at this final stage.
Concept context
Glycolysis, the Krebs cycle, the electron transport chain, fermentation, and the respiratory quotient. The cellular energy-release counterpart to photosynthesis.