Bothaerobic and anaerobic respiration involvechemical reactions which take place in the cell to produce energy, which is needed for active processes.

Aerobic respirationtakes place in the mitochondria and requires oxygen and glucose, and produces carbon dioxide, water, and energy. The chemical equation is

C6H12O6+ 6O2→ 6CO2+ 6H2O (glucose + oxygen -> carbon dioxide + water).

Anaerobic respirationalso produces energy and uses glucose, but it produces less energy and does not require oxygen. This is useful in tissues which have a high energy demand such as in working muscles, in which there isnot enough oxygen to produce all the energy needed by using aerobic respiration alone. Anaerobic respirationtakes place in the cell cytoplasm and produces lactic acid.

The chemical equation isC6H12O6 -> 2C3H6O3 (Glucose -> Lactic acid).

The lactic acid then needs to be oxidised later to carbon dioxide and water afterwardsto prevent it building up. This process requires oxygen and therefore following anaerobic respiration there is oxygen debt in the cell, as oxygen is needed to break down the lactic acid produced.