Oxygen is the final electron acceptor in the electron transport chain in aerobic respiration
The electron transport chain of the mitochondria is the means by which electrons are removed from reduced carrier NADH and transferred to oxygen to yield water.
In the cytochrome oxidase complex of the electron transport chain, four electrons interact with a molecule of oxygen and eight hydrogen ions. The four electrons, four of the hydrogen ions and the molecule oxygen are used to form water molecules.
In anaerobic respiration the final electron acceptor can be of many types such as Ferric iron which is used by denitrifying bacteria
