Respiration

There are two types of respiration; aerobic and anaerobic. Aerobic respiration uses oxygen but anaerobic doesn't.

In aerobic respiration glucose and oxygen are converted in the cells of the body into carbon dioxide, water and energy. That's why we breathe in oxygen and breathe out carbon dioxide. The glucose comes from the food that we eat.

During intense exercise anaerobic respiration takes place in the muscles creating lactic acid. This is what causes cramp.

Bread, beer and wine are all made using yeast to produce fermentation. During fermentation glucose is converted into ethanol (alcohol), carbon dioxide and energy.