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The effects of temperature on the rate at which a substrate is broken down.

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03/09/03 Biology coursework An experiment on the effects of temperature on the rate at which a substrate is broken down A. Prediction: This experiment is to test the effects of temperature on the rate at which catalase breaks down hydrogen peroxide into oxygen and other products. Therefore, if the temperature is increased or decreased, the rate, at which the proteins are broken down by the enzyme, will vary: faster if the temperature is increased and slower if decreased. B. Background knowledge: This prediction is based on many points. Firstly, as the enzymes are found in the human body, one can conclude that they work better at body temperature which is roughly around 40�C. However should the temperature rise, there would be more energy and so the enzymes would vibrate more. Consequently, they are more likely to collide and so attach to proteins. As a result, more proteins are broken down. Should the temperature be lowered, the enzymes would vibrate less, giving them a lesser chance of attaching to a protein. Therefore, the proteins are broken down at a slower rate. However, there is a limit to how high the temperature can increase as the enzymes will start to denature. ...read more.


E. Variables: - The temperature of the water bath was varied. - The rate at which the enzymes broke down the hydrogen peroxide changed (this is an independent variable). - The amount of potato, hydrogen peroxide stayed the same (this is a dependent variable). F. Results: The results were as follows: (* for a 20g piece of potato and the reaction timed for 3 minutes) Temperature of catalase (in �C) Amount of gas produced from reaction (in mL) 23 (or Room temperature) 0.4 0.4 30 3 3 40 3.8 3.6 50 5.4 4 60 5.8 6.8 80 4 4 The averages of the results are thus: Temperature of catalase (in �C) Amount of gas produced from reaction (in mL) 23 (or Room temperature) 0.4 30 3 40 3.7 50 4.7 60 6.3 80 4 G. Analysis of the results: The results seem to follow a certain pattern. The amount of gas produced from the reaction seems to start at a fairly low amount at room temperature. This amount increases as the temperature rises and it is at its optimum at 60�C. From then on, it falls. To illustrate this, graph 1 was drawn (see next page). ...read more.


At the end of a predetermined time, the gas displaced is then measured and noted. This method is effective in the sense that factors aforementioned are controlled further. For instance, when using the potato, the number of enzymes weren't the same at each experiment. In this experiment, that number is now controlled as there is always a fixed amount of catalase. Also, when using the potato, enzymes could have been lost when it was exposed to the air. In this experiment, the catalase is in powder form so none are lost. As previously calculated, the Q10 coefficients of the enzymes are more or less equal to 1.3 and most enzymes have a Q10 coefficient of 2. This could be explained by the fact that the experiment had some flaws aforementioned in this section. This could affect the prediction because, since most enzymes have a Q10 coefficient of 2, the coefficients calculated do not comply with the rule. So my prediction could be wrong. However, given these factors, the results do add up to a conclusion. Granted, the results are rudimentary (due to some of the factors previously explained) but there is a pattern: the rate does go up and having reached the optimum temperature, the rate does drop back down again. So therefore, I can conclude that temperature does affect the rate at which the substrate is broken down. ...read more.

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