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My aim is to discover how temperature effects the production of oxygen from yeast and hydrogen peroxide. I will mix yeast with hydrogen peroxide and use an upturned measuring cylinder to measure how much oxygen is produced.

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Planning Aim My aim is to discover how temperature effects the production of oxygen from yeast and hydrogen peroxide. I will mix yeast with hydrogen peroxide and use an upturned measuring cylinder to measure how much oxygen is produced. To find out how much hydrogen peroxide and yeast I will use, I will carry out pre-tests. This will also aid accuracy of the final experiment by uncovering potential flaws in the method. Hypothesis and Theory There are many ideas to suggest that the change in temperature will cause an increase of respiration in yeast. Yeast is a single cell fungus made up mostly of protein, which has been use for its applications in fermentation. Yeast, after activation creates the ferments carbon dioxide and ethyl alcohol by secreting the enzyme zymase (a complex of 12 enzymes) in the yeast, which acts on simple sugars such as glucose. The alcohol produced has been used in making wines and bears and the carbon dioxide produced has been used in baking as it gets trapped in the dough and causes it to rise. Enzymes are catalysts which speed up reactions, they are made from protein and are specific as to which substrate they work on. Enzymes basically work due to the lock and key theory, where the substrate substance (the key) fits into the active site on the enzyme and they bind together, the reaction takes place and the substrate unlocks to form one or more substances leaving the enzyme ready to perform the binding again. ...read more.


1 2 2 6 3 11 4 13 Test 2 Time (minutes) Oxygen Produced (cm3) 1 2.5 2 6 3 10 4 12 Temperature: 29�C Test 1 Time (minutes) Oxygen Produced (cm3) 1 4 2 12 3 13 4 13 Test 2 Time (minutes) Oxygen Produced (cm3) 1 6 2 8 3 12 4 13 Temperature: 39�C Test 1 Time (minutes) Oxygen Produced (cm3) 1 9 2 11 3 12 4 15 Test 2 Time (minutes) Oxygen Produced (cm3) 1 8 2 12 3 14 4 15 Temperature: 48�C Test 1 Time (minutes) Oxygen Produced (cm3) 1 7 2 11 3 13 4 13 Test 2 Time (minutes) Oxygen Produced (cm3) 1 7 2 11 3 13 4 14 Temperature: 59�C Test 1 Time (minutes) Oxygen Produced (cm3) 1 16 2 19 3 21 4 21 Test 2 Time (minutes) Oxygen Produced (cm3) 1 17 2 20 3 21 4 22 I have ensured that my results are as accurate as possible by controlling all the variables stated in my planning section. I also took care when using the equipment so as to retain continuity throughout the experiment. For this, I checked everything was set up correctly at each reading and prepared my solution in the same way. I did not prepare a batch of solutions as this would have given some more time to acclimatise and more time to react and respire, changing the conditions. AVERAGES Temperature: 29�C Time (minutes) Oxygen Produced (cm3) 1 2.25 2 6 3 10.5 4 12.5 Temperature: 39�C Time (minutes) ...read more.


This would mean the temperature is not affecting the temperature. All three of these could make the experiment inaccurate. To make sure that the results were as reliable as I could make them, I calculated the mean of two results at each interval when dealing with the rate. The obvious anomalous result is at 3 minutes with temperature 39C, this could be due to the afore mentioned flaws in the method. I took all possible precautions to make the apparatus used to be reliable and give good values do I think the slight unreliability was caused by the preparation of the solution and the unpredictability of how the reaction went that came with it. To obtain more reliable results I would want complete continuity with preparations, maybe arranging sets of substances to create multiple solutions beforehand or preparing them but not actually activating the yeast so as to prevent any getting a head start over the others. This would ensure that all the preparations are the same and would give continuity. This would help give more reliable results throughout. If I were to further investigate this experiment and my results, I would probably want to calculate the point where the enzymes begin to denature for respiration in yeast. I could also examine the change in rate between the intervals to determine validity and continuity, also running them through maybe more intricate calculations involving log. At this stage, I shouldn't think there is too much more I can do. I think it would be interesting to vary the amount of H2O2 as an extension. Nikki Newland 11R ...read more.

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