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An investigation to determine the effect of temperature on the effectiveness of catalase.

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An investigation to determine the effect of temperature on the effectiveness of catalase Aim The aim of this experiment is to determine how the rate and efficiency of the enzyme catalase is affected by change in temperature. Prediction From what I know about enzymes and their properties, the catalase will work best at approximately 37�C, will denature at higher temperatures, and work slower or not at all in low temperatures, however I do not know the extent of the effect or the temperatures at which denaturing occurs for catalase. Preliminary work As preliminary work for the investigation we have performed a number of tests to determine optimum conditions for obtaining results. The first experiment used a 1cm3 piece of potato, which contains some catalase, and 10ml of hydrogen peroxide. However we found that the reaction did not occur fast enough, and not enough gas was given off to accurately measure. We found that liver was much more effective, suggesting a higher catalase content than potato. This gave off approximately 20ml of gas at room temperature, using a 4g piece of liver. We decided to reduce the liver slightly to 2.5g so that we would stay within the maximum capacity of the measuring cylinder (50ml) ...read more.


The other bung (attached to the delivery tube for gas collection) is used to bung the boiling tube quickly and the stopwatch or stopclock will be started. Our preliminary work showed that 30 seconds should not fill the measuring cylinder but will let slower reactions react enough to be measured, so after 30 seconds the reading will be taken on the measuring cylinder and recorded. This experiment will be repeated three times to get an accurate average and three more times at each temperature. For those temperatures warmer than room temperature, the Bunsen burner will be lit and the water bath warmed slowly to the right temperature, it will be warmed slowly to ensure that the thermometer keeps up with the current temperature. Variables We are investigating the temperature variable and its effects, but other variables are: Weight of liver Surface area of liver amount of H2O2 Time left Concentration of H2O2 Fair Test In order to maintain a fair test, we will perform each experiment three times to get a fair average and to make it easier to see anomalous results. We will also try to keep all of the variables listed the same through all experiments Results Temperature (�C) ...read more.


The lower temperatures show that catalase has very little effectiveness below 30�C. This is consistent with the fact that under operating conditions in the liver, they would never become this cold. Evaluation There were a number of factors that could have affected our results that we did not intend, firstly we only used a 50ml measuring cylinder, and some of the volumes of gas given off were above 50ml, so we had to estimate the overflow. I think this was done accurately, however and so no significant impact would have been made on the accuracy of our results. Secondly after the experiments at 20�C the 2 volume H2O2 was depleted, so we had to dilute 10 volume H2O2 to the correct concentration. There is a significant increase in gas given off between 20�C and 30�C so it is possible that this new hydrogen peroxide was of a higher concentration than intended. Overall though I think we obtained clear results that followed a good pattern and agreed with our predictions, and the experiment therefore went well. Improvements we could have made would have been to test a wider range of temperatures so that we could obtain a more accurate optimum temperature, through to when the enzymes totally denature. Robert Hogan 10X ...read more.

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