Discussion : Catalase is a common enzyme which is found in almost all living organisms that is exposed to oxygen. Catalase catalyzes the decomposition of hydrogen peroxide to water and oxygen which can be shown in the equation : 2H2O2 â 2H2O + O2 Catalase is an enzyme that acts as a cellular defense for oxidative damage that is caused by reactive oxygen species (ROS). ROS are high reactive ions and free radicals that involves oxygen. ROS can impair the DNA, RNA, and proteins, in plants. ROS are produced as a regular product of cellular metabolism. ROS is produced from aerobic organisms. Oxygen ions and peroxides contributes to ROS. Catalase enzyme converts the hydrogen peroxide to water and oxygen. (Chidrawi, Robson, & Hollis, 2008) Catalase is a tetramer of four polypeptide chains, with each more than 500 amino acids long. It comprises of four porphyrin heme(iron) groups that enables the enzyme to react with the hydrogen peroxide. (Boon, Downs, & Marcey, 1997-2000) Two experiments were conducted to investigate the effects of catalase concentration on hydrogen peroxide and the enzymatic effects of materials on hydrogen peroxide respectively. The effects of catalase concentration was studied by using potato samples of different amounts, which was 5g, 10g and 15g that was tested with hydrogen peroxide. Potato was chosen due to its high presence of catalase. Potato is involved in photorespiration which is a process that prevents an unwanted ratio of absorbed light to water consumption from producing hydrogen peroxide, which can oxidize plant matter and kill the plant. Catalase converts the hydrogen peroxide into water and oxygen which can be seen through the formation of gas bubbles. In this experiment, different amount of potato samples, 5g, 10g and 15g samples were tested 3 times each to get the average number of gas produced. The enzymatic effects of materials on hydrogen peroxide was conducted with liver, manganese dioxide, and potato samples once again. Liver...