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Investigating the Effects on the Activity Rate on Catalase

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Biology Coursework By Can Erdogan 11A Investigating the Effects on the Activity Rate on Catalase Introduction Enzymes are catalysts; they speed up chemical reactions within your body. They travel through our blood. Enzymes are made up of proteins and each protein has a different type of amino acid so they can form into a different 3D shape. This causes the enzymes to have different shapes meaning that its active site is suitable for one type of substrate. This happens because each active site has a different shape to fit a specific substrate and where the enzyme and the substrate fit that's where the reaction happens. Without enzymes in our body, the chemical reactions in our system would be to slow and if it's to slow it will cause death. The Investigation The aim of our investigation was to find out the activity rate of the enzyme by changing temperature to find out what the optimum temperature is. * Yeast * Hydrogen Peroxide 5ml * 100cm� conical flask * 100 cm3 Measuring Cylinder * Washing Up Bowl * Spatula * Delivery Tube * Stopwatch * Top can Balance Yeast at Different Masses Mass of Yeast (grams) Oxygen produced in 2 minutes (cm�) 0.2 54.0 0.4 49.0 (Outlier) 0.6 58.0 Mass of Yeast (grams) Time for Reaction to end(s) 0.2 153.0 0.4 136.0 0.6 36.0 (Outlier) 0.8 37.0 (Outlier) 1.0 91.0 1.2 62.0 I have found out from the top table that the more yeast I add the more oxygen is produced. This has been indicated when the volume of O2 increases as more yeast is added. A method that we used for measuring the volume of O2 being produced is the use of the 100cm3 measuring cylinder. But this method was not very successful because it does not give accurate measurements of the volume of oxygen. From the second table I found out that the more concentration of yeast I add the quicker the reaction goes. ...read more.


The error bars on the graph for some of the points are quite large, this suggests that my results maybe unreliable. Because the shape of the graph was predicted and it was the most logical shape to be predicted. In my graph I have five results plotted down depending on the average activity rate of the enzyme. We continued using the gas syringe and it gave us rather accurate results enabling us to be able to use these results to get our optimum temperature. But what may lead my results to not be accurate is the fact that I got one outlier, meaning that a fault occurred during the experiment. The fault would most likely be a common human error, so maybe we did not put in the right amount of H2O2 in the clinical flask. The error bars on my main graph indicates that my optimum temperature may not be accurate because the error bar is quite big. A reason for why it may be big is that it was hard to maintain that temperature because the water was continuously dropping down to room temperature. The error bar (indicating the temperature at 23oC) was very small which means that there were very accurate readings when measuring the volume of O2. Taking reading may have been accurate at 23oC because the temperature was very easy to control and it was easy to control because the room temperature was between 22-24oC meaning that the temperature could not get any hotter or colder. Even though our data look very accurate we cannot be 100% certain that 45oC is the optimum temperature, this is because if we only took 5 temperatures then it's not very likely that our results would be 100% accurate because we would have to take very single temperature around the predicted optimum temperature. Another reason for why we cannot be 100% certain is because all living things have different variations of genes meaning that because of their genetic factors some may work better at different temperatures. ...read more.


But the error bars indicating the readings of 32-45oC had quite a big error bar which shows its unreliability. A reason for these inaccurate results is because that we may have not left the potato in the beaker as long as we should have. Another reason is that we did not add more water so it continued to drop down to room temperature. But the potato was not left in there long enough for the water to go down to 23oC. But there was a slight change in temperature when the potato was taken out form the beaker into the conical flask. Reasons for why the error bar at 45oC was big was because the temperature was far away from room temperature, so the temperature was hard to control so if the temperature continued to drop while the potato was in beaker. Common human error could of had a major affect on the outcome e.g. timing problem because stopping at a longer time could mean more oxygen being made, making a higher reading. Another common human error is how much H2O2 was poured into the measuring cylinder because anyone would easily have poured the wrong amount of hydrogen peroxide giving us an unfair result. My conclusion is rather reliable because my data shows quite accurate results. My apparatus have allowed me to be precise because we used a gas syringe to measure the volume of oxygen which is very accurate at measuring volumes of air. This proves that my conclusion is reliable and correct because it shows the logical explanation for my data and a clear understanding. My methods helped me to be precise because we used the units of "cm3", "ml" (when measuring how much hydrogen peroxide was poured into the conical flask) and "oC", there units were precise. My conclusion matches my data which shows that my conclusion is correct. But I cannot be 100% certain because I may not have came up other ideas for why I've got the results I have. ?? ?? ?? ?? ...read more.

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