Final answer:
The final electron acceptor in the electron transport chain of aerobic respiration is an oxygen molecule (O2), allowing for the high-efficiency production of ATP.
Step-by-step explanation:
In aerobic respiration, the final electron acceptor of the electron transport chain (ETC) within oxidative phosphorylation is an oxygen molecule (O2). Electrons carried by NADH and FADH2 travel through the ETC and their energy is used to pump protons across the mitochondrial membrane, creating a gradient that is then used to generate ATP through chemiosmosis. When these electrons reach the end of the ETC, they are transferred to oxygen, reducing it and forming water.
In the absence of oxygen, cells can resort to fermentation or anaerobic respiration to regenerate NAD+ from NADH, which allows glycolysis to continue. However, these anaerobic processes do not utilize the ETC and produce ATP at a much lower efficiency. Hence, in aerobic conditions, oxygen is crucial as the final electron acceptor for producing a high yield of ATP.