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Investagating the Action of the Enzyme Catalase On the Surface Area of a Potato.

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INVESTAGATING HOW INCREASING THE SURFACE AREA OF A POTATO AFEECTS THE AMOUNT OF OXYGEN PRODUCED AIM: My aim in this investigation is to examine how the amount of oxygen produced is affected by increasing the surface area of a potato (increasing the enzyme catalase in the experiment). I will be changing the surface area of a potato and observe how long it takes the oxygen to produce as I increase the surface area of the potato to produce oxygen. The substrate I will be using will be hydrogen peroxide and the biological catalyst will be the potato. VARAIBLES: In this investigation, I will increase the enzyme catalase in the experiment by increasing the surface area of the potato, and observe how it affects the amount of hydrogen peroxide decomposed, producing oxygen at the end of the reaction. The main variables in this investigation that affect the rate at which hydrogen peroxide is broken down are, the concentration of the hydrogen peroxide, the quantity of the hydrogen peroxide solution used, the temperature of the solution, the time at which the experiment is carried out for, the pH value of the catalyst and the surface area of the potato used. If the concentration of the solution is high, more hydrogen peroxide will be decomposed faster producing more oxygen. This is because if the concentration of the reactant is high and the reactants are more concentrated, then there are more particles for each unit of volume in the hydrogen peroxide. Since there are more particles, there is a higher possibility that the particles will attack the surface area of the potato causing a reaction and forming the product oxygen and water. Since there are more particles in the solution causing more collisions, the rate of which the hydrogen peroxide is decomposed, (the rate of reaction), will also be fast allowing more of the products to be formed in a short period of time. ...read more.


Therefore, if I time the experiment for ten minutes, this gives enough time for the substrate to be decomposed and the oxygen to be collected which will give me a better result. This will allow me to get enough results to plot a graph showing the surface area against the rate of reaction. I would repeat the whole experiment three times to ensure that my results are accurate and reliable to come to a conclusion. I will gain an average of these results as well to plot them on a graph. These changes will help me lead a good experiment, allowing me to get reliable results to base a conclusion on. I will also round off the oxygen collected to the nearest millilitre because that way the results are more accurate and reliable. During the experiment, the catalyst, the potato will remain unchanged. FAIR TESTING: To ensure that the investigation that I carry out is a fair one many factors the same for the whole investigation. * I will always use the same volume and the same concentration of the hydrogen peroxide. However, I will change the surface area of the potato used every time. * I will always take the measurements when collecting the oxygen to the nearest full millilitre, as they are more accurate results. * I will always time each experiment for 10 minutes and then note down the amount of oxygen collected. * I will also make sure that each result is repeated three times to allow me to gain an average at the end of the investigation to make my results more accurate and reliable. * I will also keep the following key factors constant. I will always make sure that the measuring cylinder is clear so that the amount of oxygen produced at the end can be seen properly. * The amount of oxygen produced also needs to be measured at eye level to gain a reliable result. ...read more.


This is because the tube got clogged with the oxygen at some points enabling the oxygen to be collected fairly. Also, I would use a gas syringe rather than try collecting over water because I found the experiment harder to conduct when I had to collect the oxygen over water because there were so may things to control A gas syringe would have been easier to observe and set up. I would also check the temperature of the experiment because at different places in the lab, the temperature varied and sometimes that allowed the catalase enzyme to work faster than other times. This is because enzyme work fastest at 370C and therefore, if the room temperature was higher at one point or one day, that may have allowed the catalase enzyme to work faster allowing more oxygen to be made. Also, not all the faces of the potato cube were attacked by the substrate easily. This is because, one of the faces of the cube, was always facing the bottom of the conical flask, not allowing the substrate to attack it. Therefore, this was not fair and not all of the six faces were attacked by the substrate. Therefore, if I was to do this experiment again, I would stick some pins or cocktail sticks into the potato cubes so that all the faces of the cubes had a fair chance for the substrate to attack and none were facing the bottom of the conical flask. A diagram below shows this. In future if I were to do this experiment again, I would repeat more results to get an even better average result. I would also try using other catalyst such as magnesium oxide and compare the results when the potato was the catalyst. I would also try using more hydrogen peroxide to see how increasing the substrate affects the same amount of catalyst. Finally, I would try testing with different pH's, to see the effect it has on decomposing the substrate. 1 ...read more.

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