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# Rates of reaction of starch

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Introduction

Hypothesis: I predict that as the temperature increases the rate of the reaction will increase until the optimum temperature and after the optimum temperature the rate of reaction will decrease. I also think the optimum temperature will be around 40 C as it is the body temperature and any temperature after 60 C will denature the enzyme. I have predicted this using my background information, which is below, and using the collision theory. Below it states that as you increase temperature the molecules move quicker and so more successful reactions occur until a certain temperature when the active site of the enzyme starts to break down and the substrate then doesn't fit and so the reaction starts to decrease and so I predict that as you increase the temperature to around 40 which is around its optimum the reaction will increase but over that the reaction will start to decrease. Background Information Enzymes are protein molecules, which can be defined as biological catalysis. A catalyst is a molecule, which speeds up the chemical reaction, but remains unchanged at the end of the reaction. Enzymes are globular proteins. ...read more.

Middle

Potato Knife Cutting Board Kettle Plan: I will collect all the necessary equipment needed. I will then chop up and measure the potato pieces weighing to 3 cm each. For every sample of potato, I test; I will set up the equipment as shown in the diagram. Before starting the experiment, I will ensure the heated water is at the right temperature and check the volume of water in the test tube so that I ensure that the results are fair and reliable. Then I will start by adding 5cm� of Hydrogen Peroxide into a test tube. I will then cut a piece of potato with a cork borer, using size 4. The next step would be to boil the kettle so we can then add cold water to decrease the temperature down to what is needed for the experiment. Use a thermometer to measure the temperature. When the temperature is correct I will place the test tube into the beaker filled with the heated water. I then will add the potato and the hydrogen peroxide in the test tube. I will quickly then close the bung onto the test tube and place in position. ...read more.

Conclusion

I must also assume that the substrate concentration is the same within the same potato but I cannot be sure and so I must take this into consideration when looking into the reliability of my results. I will do the experiment 2-3 times so that I can get an averaged result and more reliable set of data. I will obtain my set of data by timing the breakdown of the substrate until it is broken down all the way till the outside. I will also have to peel the outside layer of the potato, as it is not digestible and so will alter the results and time it takes to react. To heat the enzyme instead of using a Bunsen burner, which is harder to control, I am going to use cold and boiling water to get rite temperature by mixing the cold and hot together. The temperatures I am taking are at 0 oC, 10 oC, 20 oC, 37.5 oC, 50 oC, 60 oC, and 70 oC. I have increased it in a systematic way so that I can get a large set of data and draw an accurate graph from these results. ...read more.

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