Final answer:
In aerobic respiration, oxygen is the final electron acceptor, while in anaerobic cellular respiration, organisms may use alternative electron acceptors.
Step-by-step explanation:
In aerobic respiration, the final electron acceptor is oxygen. Oxygen is the terminal step in the electron transport chain and creates water inside the mitochondria. It is the recipient of the free hydrogen at the end of the electron transport chain. Without oxygen, organisms may use alternative electron acceptors, including organic and inorganic molecules, in a process called anaerobic cellular respiration.