What is the role of oxygen in the electron transport chain, and why is it so essential?

Oxygen acts as the final electron acceptor in the electron transfer chain, resulting in the formation of H₂O. This is essential because without it, the electron transfer chain cannot function resulting in a lack of oxidative phosphorylation in the inner membrane of the mitochondria. Further more, the lack of functioning electron transport chain means that NADH and FADH₂ cannot be oxidised, creating a lack of NAD+ and FAD, which are coenzymes for reactions in the Link reaction and the Krebs cycle.Consequently, during anaerobic respiration only glycolysis can occur. This reduces the ATP production of aerobic respiration from 38, to the ATP of anaerobic respiration of 12, as well as producing waste products such as lactate which must be removed.