Final answer:
The last electron acceptor in the ETC is oxygen, which is reduced to water by the final ETC carrier.
Step-by-step explanation:
In aerobic respiration, the final electron acceptor in the electron transport chain (ETC) is oxygen (O₂), which is reduced to water (H₂O) by the final ETC carrier.
This process is essential for ATP production, as it drives the entire set of ATP-producing reactions within the mitochondrion.
This is why we must breathe in oxygen to provide the necessary electron acceptor for the ETC to generate ATP and supply energy to the cells.