During aerobic respiration, which molecule acts as the final electron acceptor in the electron transport chain?

• A. Glucose
• B. Carbon dioxide (\(CO_2\))
• C. NADH
• D. Oxygen (\(O_2\))

Answer: (D)

Verified step by step guidance

1. Understand the concept of aerobic respiration: Aerobic respiration is a process where cells generate energy (ATP) by breaking down glucose in the presence of oxygen. It involves glycolysis, the citric acid cycle, and the electron transport chain.
2. Learn the role of the electron transport chain: The electron transport chain is the final stage of aerobic respiration, where electrons are transferred through a series of protein complexes embedded in the inner mitochondrial membrane.
3. Identify the role of the final electron acceptor: Electrons are passed down the chain to progressively lower energy states. At the end of the chain, the final electron acceptor is required to complete the process and prevent the accumulation of electrons.
4. Recognize the molecule that acts as the final electron acceptor: Oxygen (\(O_2\)) is the molecule that accepts electrons at the end of the electron transport chain. It combines with electrons and protons (\(H^+\)) to form water (\(H_2O\)).
5. Understand why other options are incorrect: Glucose is the initial substrate for respiration, not the electron acceptor. Carbon dioxide (\(CO_2\)) is a byproduct of respiration, and NADH is an electron carrier that donates electrons to the chain, not the final acceptor.