Which molecule serves as the final electron acceptor in the electron transport chain?

Oxygen serves as the final electron acceptor in the electron transport chain during cellular respiration. This process occurs in the mitochondria and is essential for the production of ATP, which is the energy currency of the cell. As electrons are transferred through a series of proteins in the inner mitochondrial membrane, they ultimately reach oxygen molecules.

When oxygen accepts electrons, it also binds with protons (hydrogen ions) to form water, a byproduct of this metabolic process. This step is crucial because it allows the electron transport chain to continue functioning; without oxygen to accept the electrons, the entire chain would become backed up, halting ATP production and energy metabolism.

The other molecules, such as nitrogen, carbon dioxide, and glucose, do not play this role in the electron transport chain. Glucose is a substrate that is broken down during earlier stages of cellular respiration (glycolysis and the Krebs cycle) to provide electrons, while nitrogen and carbon dioxide are not directly involved in the electron transport process. The unique role of oxygen as the final acceptor is vital for aerobic respiration, allowing organisms to efficiently convert biochemical energy from nutrients into ATP.