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Factors affecting the activity of potato catalase on hydrogen peroxide.

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Introduction

Biology coursework Factors affecting the activity of potato catalase on hydrogen peroxide Aim: This experiment is based on the simple aim of finding the factors affecting the activity of potato catalase on hydrogen peroxide. We are going to set up an experiment which involves a test tube with different hydrogen peroxide solutions, then we will have to slices of potatoes into the test tube, then we will put a bung and measure the amount of oxygen given off in a cylinder. Prediction: There are many factors affecting the activity of potato catalase on hydrogen peroxide. The main factors affecting this experiment are: pH, the temperature, concentration enzyme (amount of potato), concentration of substrate and surface area of potato. Lock and key principle: Enzymes work at a lock and key principle, any factors which affect this reaction will increase the rate of reaction. Enzymes are basically biological catalysts, so if something speeds the reaction making enzymes move faster, then more enzymes will join the large molecule structure. This will then form more substrate complexes and then more enzymes and more products. This is why I predict that as hydrogen peroxide increases the O2 will also increase, because there will be more molecules substrate for enzymes to join to. Enzymes are proteins which break down molecules and there are two types: constructive and destructive. The active site of an enzyme is the region that binds the substrate and contributes the amino acid residues that directly participate in the making and breaking of chemical bonds. Enzymes convert substrates to products by breaking and making chemical bonds This diagram shows us how the lock and key principle works. pH The pH affects the rate of reaction, in such a way that the whole experiment could be a disaster. If the solution is to acidic or to alkaline the enzymes will work worse and the rate of reaction will decrease tremendously. ...read more.

Middle

test tube where the H2O2 and potato chips are; which contain the enzymes used to catalyse the H2O2 to help produce the oxygen a lot quicker. We will fill up the beaker with water so oxygen will not escape. We used the water in the measuring cylinder to measure the overall amount of oxygen produced by seeing how much the oxygen has been trespassed from the test tube with the catalyse to the measuring cylinder. Here we can see a diagram representing our experiment. The only thing missing are the two clamp stands which would hold the measuring cylinder and the test tube To collect our data we will be measuring the amount of oxygen produced from the reaction, by letting it pass through a tube and let it go up the measuring cylinder, which will have water up to 10ml�, that way we can start to read our results because if we had started at 0ml� the lines were difficult to read. Then every 30 seconds we will see how much oxygen has got up to the surface and so we will record it. Then we will put our results into a line graph. However when a period of 300 seconds have passed we will remove the tube from the cylinder and start the same procedure with another solution. I am going to use 5 minutes of time so that it was enough time to get the reaction going. The water produced by the reaction will stay in the boiling tube and only the oxygen will pass through the tube and reach the surface at the top of the bottom of the measuring cylinder. I knew my results were reliable because I saw that as the concentration increased the rate of reaction grew tremendously. The experiment was done two times, one done at 7�C and another one at 17�C and the 17 �C one had a bigger rate of reaction than the one at 7�C. ...read more.

Conclusion

In the first place, when we wrote down our results every 30 seconds, we might have read them wrong. So then the results would be slightly wrong and they would be carried across all the experiment affecting our final results. But unfortunely we did not have equipment to solve this and we just had to look at it and record it. The hydrogen peroxide could have also been put in a water bath while doing the experiment so there were not any changes and the temperature could remain the same. We could have also made more readings, and so we would have gotten more results to plot on our graphs. Maybe doing 9 H2O2+ 1H2O, 8H2O2 + 2H2O, etc. Or even with decimal places, 9.5 H2O2 + 0.5H2O, 8.5 H2O2 + 1.5H2O, etc. We also could have changed other variables like the surface area of the potatoes by cutting them in smaller peaces, so then we could compare results. Another problem was placing the bung inside the test tube. When we tried to put the bung inside the test tube after a few seconds it automatically came out and so in some of the concentrations we had to push it during five minutes, so that means that more pressure was being made and so more oxygen would be given out. When we cut the potatoes we could have done it with an electronic ruler which would have given us up to three decimal places. The clining film was not very good and it braked easily so when we opened it to get some potato slices we had to use more clining film. Another problem is that there were not enough clamp stands to hold the test tubes and so we had to use one for the test tube but we could not use one for the measuring cylinder. Well on the whole the experiment ran smoothly, the equipment we used was not necessarily very good but considering what the school had I think it was the best material in the school. ...read more.

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