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In this investigation the effects of catalase on varied concentrations of hydrogen peroxide. By measuring the amount of oxygen given off.

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Introduction

Enzyme investigation Aim: In this investigation the effects of catalase on varied concentrations of hydrogen peroxide. By measuring the amount of oxygen given off. Variables: these are the possible variables: Temperature Concentration of hydrogen peroxide Surface area of liver (catalase) Time The variables that will be kept constant will be surface area of liver because it is easier to cut multiple pieces of the same size rather than changing them all the time. Time will be kept constant which is very easy to control, and concentration will be kept as it comes out of the bottle. Temperature will be the variable that is changed. It should be easy to do by putting the liver in the conical flask in a water bath heated by a Bunsen burner and over 1 minute the temperature shouldn't change too much to affect results. Background information: An enzyme is a specialised organic substance, made up of amino acids (or proteins) that act as catalysts which determine the speed of reaction in living organisms. They are not alive themselves. An enzyme basically finds the substrate that it has the function to breakdown, and it breaks it down into more simplified pieces. There are theorems to say how an enzyme works exactly, one is the "lock and key hypothesis" which is when the enzyme acts like a lock and the substrate is the key but only one "key" (substrate) will fit any given "lock"(enzyme). ...read more.

Middle

and the time will start as soon as I start to inject the 10 % hydrogen peroxide solution. Then once 1 minute has passed the amount of gas produced will be read and recorded also the weight of the liver. This will be repeated for each temperature and then again and again to make a total of 3 tests for each temperature. Prediction: My prediction is backed by the collision theory because I believe that the more heat there is the more kinetic energy and the more collisions which should mean more reactions. Although I also believe that the proteins will denature due to the temperature being too high and the enzymes cannot function properly, thus slowing down the rate of reaction. Because this is what happened in my preliminary results that I carried out on a laptop. I think the optimum conditions will be about 35 - 40oc because this is the kind of temperature that the living body operates at. I think the graph will look a bit like this: This will show my optimum temperature and the temperatures that the proteins (enzymes) denature on either side of the optimum as you can see. Fair test: All tests will only last one minute. All pieces of liver will be the same size (or as close as possible). Concentration of hydrogen peroxide will be as it comes from the bottle. The temperature will be the only variable changed. ...read more.

Conclusion

Evaluation: My investigation compared to my original intention was fairly good because the collision theory I used to predict my results also explained my final results without being too tentative. My points mainly fit the line of best fit but there are a few anomalous results as you can see by my graph these maybe due to that the solutions weren't the right temperature to start off with, or the pieces of liver of these anomalous results were slightly bigger than the others; however there is a clear trend. I could have improved the procedure by using a water bath that was set to the exact temperature so I would have had no temperature that were a few degrees celcius out which may have cause anomalies. Also I should have left the liver in the bath for longer without adding the hydrogen peroxide so the catalase had time to reach the temperature aimed and this would allow any enzymes to reach the right temperature. I could have improved this experiment by using an electric water bath that is set to one specific temperature which is a lot more precise and a lot easier. I could extend this experiment by perhaps looking at the temperature closer and having the range of temperature based immediately around the optimum temperature I found on this experiment. Or I could investigate into another variable such as pH or surface are of liver. Even though I could have improved my experiment the results compared to my preliminary results fairly evenly. ...read more.

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