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To investigate the effect of temperature on enzyme activity. The enzyme used will be catalyse.

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Experiment Plan Experiment: To investigate the effect of temperature on enzyme activity. The enzyme used will be catalyse. The enzyme catalyse: The enzyme catalyse is a biological enzyme. It is used to break down Hydrogen Peroxide, which is harmful. The reaction that occurs is: Hydrogen peroxide Water + Oxygen The activity of the enzyme catalyse can therefore be measured by the amount of oxygen (in the form of froth) that is produced. Prediction: The enzyme catalyse will have an optimum temperature of between 40�-45�. If the temperature rises above this temperature range or below this temperature range, the rate of enzyme activity will fall. This is because the enzyme catalyse is a protein enzyme and a biological catalyst, and the optimum temperature of most biological catalysts is between 40�C-45�C. If the temperature rises above this, the enzyme activity will slow down because the enzyme will be denatured. This means that the active site will be changed. Enzymes only work if the substrate fits into to the enzymes active site, like a lock and key (see diagram). The reaction then takes place and the product leaves. If the active site shape is changed the substrate will no longer be able to fit in (see diagram). This means that the reaction can no longer take place. As the temperature gets higher above 45�C, more enzymes will be denatured. The higher the temperature above 45�C, the slower the reaction rate. ...read more.


Temperature (�c) Volume of oxygen produced (cm ) 1 Volume of oxygen produced (cm ) 2 Volume of oxygen produced (cm ) Average Ice 10 9 3 6 Room 20 47 46 46.5 30 12 20 20 40 17 Not tested 17 50 5 4 4.5 60 3 Not tested 3 70 3 Not tested 3 The results that are highlighted grey are considered anomalies, so have been discounted from the average. Analysis Conclusion: The results show that the optimum temperature for catalyse to work at is 20�C. Looking at the initial part of the reaction (see graph), between 10 and 20�c the gradient of the graph was quite steep. Between 20�c and 30�c the gradient of the graph was also steep, but after 40�C the line begins to level off. These results partly do and partly do not support the prediction. As the prediction stated, the reaction time was slower at the coldest and hottest temperatures. This is because at lower temperatures the enzymes do not move with as much energy. This is because of kinetic theory, which states that the more heat energy a particle has, the faster, and with more energy, it will move. At 10�C the particles of the catalyse have less kinetic energy, so collide with the particles of the hydrogen peroxide with less energy. Therefore a reaction is less likely to take place, and less oxygen (in the form of froth) ...read more.


The results for this experiment gave the optimum temperature for the catalyse as 20�C. Although I did suggest a reason for this in my conclusion, it is possible that my prediction was correct and that that result was a n anomaly. In order to ensure a greater reliability of results, I should have repeated each experiment 3 times. Unfortunately, there was not enough time to do this. In addition, when I plotted my results in a rough graph, (see below) I noticed that the result for 30�C did not fit in with the trend of the data. I therefore looked at my data for the result for 30�C, and decided that the result 12 cm was an anomaly. It was possibly caused by too much potato being left in the syringe, meaning there was less catalyse in the experiment. I believe I collected a suitable range of results for this experiment, as the results I collected enabled me to see a pattern clearly. However, as I believe that the pattern shown by my results would continue beyond the range specified, If I repeated this investigation I would develop it by also using the temperatures 0�C, 80�C, 90�C and 100�C. Another good way of developing this experiment would be to have the temperatures used closer together, e.g. 20�C, 25�C, 30�C, etc. Having closer together temperatures would make it clearer to see at what temperature which denaturing took place. ...read more.

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Here's what a teacher thought of this essay

4 star(s)

A good understanding of the theory behind the investigation is shown but some weaknesses in the method followed are evident.

Marked by teacher Adam Roberts 10/05/2013

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