Respiration of the breaking down of food to create energy, or in more scientific terms respiration is the release of energy from glucose or another organic chemical. The chemical energy in glucose can be used to provide the energy required for growth, repair and movement.
The normal form of respiration. It requires oxygen and releases the most energy from glucose. When we respire like this we have to breathe oxygen in and breathe carbon dioxide out. We also have to excrete (get rid of) the extra water in our urine.
Also releases energy from glucose, but it provides us with a lot less energy than with aerobic respiration. When yeast respires anaerobically it produces carbon dioxide and alcohol. When we respire we produce lactic acid.
Too much lactic acid poisons our muscles (you get cramp).