Processes of Life

Your body needs a supply of materials to keep it alive. Substances enter and leave the body and are transported to and from cells by the blood.

You need substances from food for growth and for making new cells. Digestion of food makes these substances available.

You need oxygen to get energy from food by respiration. The air you breathe in provides oxygen.

You need to get rid of waste substances which your body makes. This is called excretion.