"To See What Factors Affect The Decomposition Of Hydrogen Peroxide By The Enzyme Catalase Which Is Found In The Liver" Introduction: Enzymes are biological catalysts. They speed up the chemical reactions which go on inside living things. Without them the reactions would be so slow that life would grind to a halt. Enzymes work by when a substrate molecule bumps into a molecule of the right enzyme, it fits into a depression on the surface of the enzyme molecule. This depression is called the active site. The reaction then takes pl