Final answer:
Aerobic respiration requires oxygen as the final electron acceptor, while anaerobic respiration can use an organic or inorganic molecule. NADH must be reoxidized to NAD+ for reuse as an electron carrier in the absence of aerobic respiration.
Step-by-step explanation:
In aerobic respiration, the final electron acceptor is an oxygen molecule, O₂. If aerobic respiration occurs, then ATP will be produced using the energy of high-energy electrons carried by NADH or FADH₂ to the electron transport chain. If aerobic respiration does not occur, NADH must be reoxidized to NAD* for reuse as an electron carrier for the glycolytic pathway to continue.
Some living systems use an organic molecule as the final electron acceptor, while others use an inorganic molecule. Both methods are called anaerobic cellular respiration in which organisms convert energy in the absence of oxygen.