What is respiration?

Respiration is not just a gas exchange, oxygen for carbon dioxide. Oxygen is the one critical part of a larger process and carbon dioxide is simply a by product of the process. Cellular respiration a complex series of chemical reactions where sugars are broken down to release energy by the use of oxygen. (Gottfried, 1993). The key is not the gases that are released, but the energy. The next concern is who or what does cellular respiration. It is commonly thought that organisms with some form of respiratory system can respire and that is true, animals undergo cellular respiration, but we are not alone. Because every living organism is composed of cells, and all cells need energy to function, then every organism must carry out some form of cellular respiration.