Hydrogen peroxide, the same mild acid used in disinfectants and hair dyes, is produced in the body, by certain white blood cells and has the vital role of killing, bacteria, viruses and toxins and maintain a healthy body. In this experiment, the floating disk method was used to observe how catalase enzyme activity was affected by the concentration of substrate. Ultimately, this imitates the reactions that occur in the human body when the catalase enzymes break down and balance the hydrogen peroxide. A small disc of filter paper, which had been soaked in yeast, was placed into a hydrogen peroxide solution. The yeast catalase then reacted with the hydroxide peroxide, producing oxygen and water, presented by; H2O2 →H2O +O2. This oxygen produced…show more content… The dependent variable in this experiment is the reaction rate of the disks. The independent variable is the varying levels of hydrogen peroxide( 0 %, 0.1 % 0.2 % 1% 3% ,5 % ) in 40 mls. Maintaining a few factors constant was vital in this experiment. Firstly, the 40 mls of each hydrogen peroxide solution was kept constant, as controlling the amount of hydrogen peroxide solutions ensures that the same amount of hydrogen peroxide molecules is available for reaction in the beaker. The temperature is another factor that was kept constant throughout the duration of the experiment, as the enzyme activity is affected by temperature. Due to this, the experiment was carried out in room temperature. The size of the paper discs also required to remain constant throughout the experiment so that the amount of oxygen gas required to lift it to the surface remains unchanged for each trial. And finally the yeast solution, and the scales used to weigh the amount of…show more content… As the concentration of the hydrogen peroxide was increased, the reaction rates also increased. However, it must be considered that the enzyme will reach a point where more enzyme molecules are available to accept than substrate molecules (Sheppard, T 2010), causing the results to plateau. At this point, the enzyme has reached its optimum value, and the only way the enzyme concentration can make a difference is if the substrate concentration is further increased (Sheppard, T 2010). The same applies for the substrate, eventually it will reach a point where more substrate molecules exist than enzymes and even if the concentration is raised, no reaction will occur due to inadequate enzyme molecules to meet this supply. For the plateauing to be observed within this experiment, a higher concentration level of hydrogen peroxide was required as the reaction rate continued to increase even with the 5 % hydrogen peroxide