One of the most important enzyme-controlled processes in living things is aerobic respiration. it takes place all the time in plant and animal cells.

Respiration takes place in the mitochondria. Mitochondria are tiny rod-shaped organelles, they have a folded inner membrane. this provides a large surface area for the enzymes involved in aerobic respiration. the number of mitochondria in a cell shows you how active the cell is.

Reasons for respiration

Your muscles use a lot of energy. Muscle tissue is made up of protein fibres. These contract when they are supplies with energy from respiration. Muscles fibres usually occur in groups known as muscles, which contract to cause movement.