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In this investigation I will perform two experiments in an attempt to determine what the best temperature is for Catalase to do its job as an enzyme in breaking down Hydrogen Peroxide.

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Investigating the factors effecting the breakdown of Hydrogen Peroxide by the enzyme Catalase Introduction: In this investigation I will perform two experiments in an attempt to determine what the best temperature is for Catalase to do its job as an enzyme in breaking down Hydrogen Peroxide. Catalase as a catalyst: Catalase is a powerful catalyst that is found in the Liver. It has the ability to quickly efficiently and safely breakdown and neutralise the threat of Hydrogen Peroxide. Without this enzyme the body would be poisoned by the Hydrogen Peroxide and die. Like most enzymes Catalase has an optimum functioning temperature of about 37 degrees Celsius. However if the temperature is too low it may not work, or if it is too high say about 75 degrees, the enzyme may die and cease to function. Why does hydrogen Peroxide need to be broken down in the Human Body? Hydrogen Peroxide is a poisonous chemical which is the by-product of bodily functions, such as digestion. It is vital that the Hydrogen Peroxide is broken down so it does not poison the body and kill. The body does this by releasing the enzyme Catalase to attack and breakdown the Hydrogen Peroxide into water and Oxygen. Chemicals I will be using: I am going to use the chemicals Hydrogen Peroxide (H2O2), and the Yeast fungus which will provide the Catalase. The Yeast has been diluted in Water (H2O) and will be used in varying concentrations according to the percentage of yeast used in the water. The experiment will release the chemicals Oxygen (O2(g)) and Water(H2O(l)). ...read more.


I would theorise that the concentration of Hydrogen Peroxide may have been too high, but I didn't actually do anything with the supply of H2O2 so this rules out that theory. Rate of Reaction: By dividing the time by the volume of chemicals used I can work out the rate of reaction. I can compare the rate of reaction in this preliminary to the real experiment and hopefully decide which is the most commanding variable. The rate of reaction for this experiment is: Looking at these rates of reaction i can assume that 2% Yeast was not done properly. The gaps in time between the other 3 experiments are all a few milliseconds but 2% Yeast is more than 2 seconds ahead. Possible causes of Anomalous Readings: One factor that I highly suspect is that I did not have the correct amount of Water in the Burette. This would make it take longer, thus giving a strange reading. Another possibility could be Oxygen leaking away. Some of the Oxygen may have escaped from the bung or the delivery tube. Making sure the bung was tightly fitted or selotaping the delivery tube to the top of the bung to let no Oxygen out may have been a good thing to do. I would also suspect the status of the Yeast might have been influential. If it was not evenly mixed i.e. most of the Catalse was at the bottom like a silt, then it would have taken longer for the H2O2 to reach it and initiate the reaction. ...read more.


Graph Analysis: The above graph has shown me that as the concentration increases, so does the time it takes to react. 4 vol.= 0.32 20 vol.=1.18 - 0.86 over 16 volumes. 0.86 divided by 16 vol gives an increase of 0.05 per each vol. This proves my theory. I can explain this rise in rate of reaction because there will be more H2O2 for the Catalase to react with. This means there will be more collision between the enzme and H2O2 so the rate of reaction will increase. My graph shows a straight line of increases. However I cannot explain why it curves at the top, beacuse surely it would keep going straight. The only possible explanation for this I can make is that I performed the experiments inaccurately and made a few mistakes. Evaluation: I think the results were workable and fairly reasonable, and they did what they were supposed to do by allowing me to prove my theory. One possible reason for the apparent wrongness of 4 vol. H2O2 I suspect is that the concentration was not as accurate as it could have been. I may have used too much or even too little water, or the Yeast may have been too weak on the 1st and 3rd try, but as it should have been on the 2nd attempt. I do not think Oxygen Leakage (as mentioned in the preliminary) could be a major factor but once again I must suspect the accuracy of the amount of water in the burette. ...read more.

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