Oxygen serves as an electron acceptor. When food is completely metabolised in the organism, it is decomposed to electrons, protons and CO2. The electrons are carried by NADH to mitochondria, to electron-transport chain. At the end of the electron transport chain, oxygen receives electrons, thus providing for maximal yield of energy carried by those electrons (in the electron-transport chain, they are used for pumping protons across the mitochondrial membrane, thus proton gradient which empowers ATPase, is maintained). At last, the ATPase enzyme produces ATP, the usable form of energy. *Aerobic respiration requires oxygen, whereas anaerobic respiration takes place in the absence of oxygen.
*Most of the plant and animal cells use aerobic respiration. On the other hand, anaerobic bacteria, yeast cells, prokaryotes, and muscle cells perform anaerobic respiration.
*Aerobic respiration is more efficient than anaerobic respiration. For one molecule of glucose, aerobic respiration produces 38 ATP molecules, whereas anaerobic respiration produces just 2 ATP molecules.
*Aerobic respiration usually takes place in the mitochondria, while anaerobic respiration takes place in the cytoplasm.
*In case of aerobic respiration, the end products are carbon dioxide and water. In anaerobic respiration, the end products are ethyl alcohol or lactic acid, and carbon dioxide.
*Aerobic respiration takes a longer time to release energy. Anaerobic respiration is a much faster process.