What is the primary role of the aerobic electron transport chain in cellular respiration?

• A. To generate ATP by using the energy released from electrons transferred to oxygen
• B. To break down fatty acids into acetyl-CoA
• C. To directly synthesize glucose from carbon dioxide and water
• D. To convert pyruvate into lactic acid under anaerobic conditions

Answer: (A)

Verified step by step guidance

1. Understand the context of cellular respiration: Cellular respiration is the process by which cells generate energy in the form of ATP. It involves multiple stages, including glycolysis, the citric acid cycle, and the electron transport chain.
2. Identify the aerobic electron transport chain: This is the final stage of cellular respiration, occurring in the inner mitochondrial membrane. It uses oxygen as the final electron acceptor.
3. Explain the mechanism: Electrons are transferred through a series of protein complexes (Complex I, II, III, and IV) in the electron transport chain. This transfer releases energy, which is used to pump protons (H⁺) across the mitochondrial membrane, creating a proton gradient.
4. Describe ATP synthesis: The proton gradient drives ATP synthesis through the enzyme ATP synthase. As protons flow back into the mitochondrial matrix, ATP synthase catalyzes the conversion of ADP and inorganic phosphate (Pi) into ATP.
5. Clarify the primary role: The aerobic electron transport chain's main function is to generate ATP by utilizing the energy released from electrons transferred to oxygen, which combines with protons to form water.