The final electron acceptor in aerobic respiration is oxygen, according to McGraw Hill Education. A molecule other than oxygen is the final electron acceptor in anaerobic respiration, pyruvate. Both of these processes occur during cell metabolism.
Chemo-trophic micro-organisms vary in terms of their electron acceptors and their energy sources. Fermentation occurs when an organic energy source is degraded and oxidized without the use of an exogenous electron acceptor; when the energy source is degraded and oxidized in the absence of this electronic acceptor, the process is known as respiration. Respiration can be aerobic or anaerobic, depending on the final electron acceptor.