Respiration is the chemical process that supplies the body with energy for all other life processes: growth and repair of cells, muscle contraction, protein synthesis, sending nerve impulses, absorbing molecules in active transport to name just a few. It happens in ALL living cells, not just animal cells but also plant cells. There are two types of respiration: aerobic and anaerobic respiration. Aerobic means “with air” and so needs oxygen, whereas anaerobic respiration doesn’t need oxygen. Aerobic respiration releases energy in cells by breaking down food substances whilst in the presence of oxygen. It is represented by this simplified equation Glucose + Oxygen —– Carbon Dioxide + Water + Energy. Glucose is broken down by oxygen to release the by-products of carbon dioxide and water. Energy is released, which is then used to make a special energy molecule called ATP. ATP is how energy is stored for later use by the body. Aerobic respiration happens all the time in all cells, usually in the mitochondria.