Final answer:
The final electron acceptor in the electron transport chain of cellular respiration is oxygen. Oxygen is essential for the efficient production of ATP through aerobic respiration. Without oxygen, cells resort to less efficient methods like fermentation to sustain ATP production.
Step-by-step explanation:
In the electron transport chain of cellular respiration, the final electron acceptor is oxygen. This is crucial because oxygen's role is central to the process of aerobic respiration, which allows for a high yield of ATP from glucose.
Oxygen acts as the terminal electron acceptor at the end of the chain, receiving electrons that have cascaded down the transport chain, and combines with free protons (H+) to form water.
When oxygen is not present, cells may turn to anaerobic processes, such as fermentation or anaerobic respiration, to continue generating ATP, albeit much less efficiently. In these processes, electrons are transferred to organic or inorganic molecules other than oxygen to regenerate NAD+ from NADH, allowing glycolysis to continue.