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For this practical I will see how temperature affects the rate of respiration with yeast. To do this I will conduct an experiment which will test this in the most fair and safe way.

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Biology Practical Assessment Coursework Planning For this practical I will see how temperature affects the rate of respiration with yeast. To do this I will conduct an experiment which will test this in the most fair and safe way. My prediction for the experiment is that the yeast will respirate the most carbon dioxide at 40*C this is because yeast is an enzyme and we have enzymes in our body and they work best at our core body temperature which is 37*C. Yeast is a single celled organism and it uses sugar that is needed to react with the oxygen these react to respirate which produces three products; carbon dioxide, water and energy but to do this the molecules must collide. The molecules at different temperatures will have various collision rates this is how at which temperature the yeast will respirate best at. The higher the temperature the more collisions will occur which will increase the reaction rate so the yeast will respirate at higher rate but only to a certain point because if the temperature is too high the enzymes begin to naturise and don't work properly so the rate of respiration will begin to drop. ...read more.


- after the practical has been finished mark results into the results table and see if there are any anomalies and confirm if you wish to do any of the temperatures again but only if there is time. Results These where the results that we got from the practical. Water displaced with Carbon dioxide in cm3 Temperature in *C First test Second test 30 5 5 40 11 10.5 50 15.5 14.5 60 9.5 8 70 2.5 2 All of these results followed a pattern apart from one which is the most of the trend by 1.5 mm3 which is at 60*C on the second test but it isn't an extreme anomaly. The averages are; 30*C = 5 40*C = 10.75 50*C = 15 60*C = 8.75 70*C = 2.25 My results show that at 50*C the enzymes worked best. At 30*C the enzymes respired at quite a slow rate but then at 40*C the respiration rate increased by double this is because there was more heat so more kinetic energy was gained allowing a higher rate of collisions to occur so an increase in reaction speed. At 50*C the most amount of water was displaced by carbon dioxide this follow the same reason as before accept that the molecules were moving even faster. ...read more.


I feel that the results were accurate as we didn't have any anomalies and the results from both test were similar and were as far as 1cm3 off apart from one which was 1.5cm3 off so we noted that as a half anomaly but we found it as not much of an interest also the results repeated ach other as well. We as a group didn't come to any problems and neither did I with the practical technique but there was a problem which wouldn't have been any easy to resolve and that was then tome available basically perfect timing and organisation would have helped with that but then there was the other groups to wait for. If there any ways to improve the experiment it would be to ask for more time so we can do the experiment a few more times for more reliable result to work with and if any serious mistakes were made there would be time to recover from them. If we had more time we could also have extended the practical by maybe seeing if the strength of the solution would change the amount of carbon dioxide released and if other solution that were to be mixed in would make a difference. ...read more.

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