Which of the following best describes the role of oxygen in aerobic metabolism?

The role of oxygen in aerobic metabolism is fundamentally tied to its critical function in the breakdown of carbohydrates and fats to produce energy. In aerobic metabolism, oxygen acts as the final electron acceptor in the electron transport chain, a central process that occurs within the mitochondria of cells. This pathway efficiently generates adenosine triphosphate (ATP), the energy currency of the cell, by oxidizing carbohydrates and fatty acids.

When carbohydrates and fats are metabolized in the presence of sufficient oxygen, glucose and fatty acids are converted into carbon dioxide and water, releasing energy that is captured in the form of ATP. This process supports sustained, lower-intensity physical activities and endurance sports, allowing the body to utilize oxygen to maximize energy production over prolonged periods.

The other options highlight different aspects of metabolism but do not accurately reflect the specific role of oxygen in aerobic metabolism. Selectivity for carbohydrate and fat oxidation using oxygen significantly distinguishes aerobic metabolism from anaerobic pathways, which generate energy without oxygen but at a much lower efficiency. Understanding this distinction is important for comprehending how the body generates energy under different physical activity conditions.