Catalysts speed up the rate of the reaction; lowers the energy input required for a chemical reaction to happen. It remains unchanged at the end of the reaction. Prime purpose of this lecture is to present on Enzymes: Biological Catalysts. Enzymes are Biological catalysts. Enzymes control chemical reactions that take place in the cytoplasm. Catalyses in an example of an enzyme made by living cells. The enzyme catalase breaks down the waste substance hydrogen peroxide into water and oxygen.