The body of every living animal and plant is a chemical factory. In fact, if all kinds of chemical changes weren’t constantly taking place, life would be impossible. You are able to use food, breathe, grow, and move because of the chemical changes which take place m the cells, tissues, and organs of your body.

Here is an example of this chemical life process. You eat a piece of bread, or a cereal, or a potato. The starch in this food is changed into sugars which go into the blood. There they are burned by the oxygen which is in the air you breathe, and your body obtains energy.