Respiration is a series of exothermic reactions that occur in the mitochondria of living cells in order to release energy from food molecules.

This energy can then be used to produce heat, for movement, growth, reproduction and active uptake.

There are 2 types of respiration - aerobic and anaerobic.

Aerobic respiration

Aerobic respiration happens in the presence of oxygen and releases more energy than anaerobic respiration.

A swimmer

Aerobic respiration word equation:

glucose + oxygen → carbon dioxide + water + energy

Aerobic respiration balanced chemical equation:

C6H12O6 + 6O2 → 6CO2 + 6H2O + energy

Anaerobic respiration

Anaerobic respiration happens in the absence of oxygen

It occurs during strenuous exercise. The buildup of lactic acid causes muscle soreness.

Anaerobic respiration word equation (in mammalian muscle cells):

glucose → lactic acid + energy

Anaerobic respiration word equation (in yeast cells):

glucose → alcohol + carbon dioxide + energy

The alcohol produced is the basis of wine and beer production.