Respiration occurring in the absence of oxygen. In a process not involving oxygen, it ensures that foodstuffs, usually carbohydrates, are partially oxidised, with the release of chemical energy. The energy yield of this type of respiration is lower than that of aerobic respiration. It occurs in bacteria and yeast as well as in muscle tissue when oxygen is absent. An illustrative example of anerobic respiration is the fermentation of alcohol in which one of the end products is ethanol.
See Aerobic respiration, Lactic acid