The Rate Of Respiration In Yeast And — страница 2

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states that, with an increase in temperature, the rate of reactions will increase. This is due to the increase of speed of the particles, brought about by the extra energy given to them by heat. Faster particles will bring about more particle collisions and so the reaction will take lace faster. Enzymes are sensitive to temperature changes up until a certain temperature and will increase in their activity also. The reactions that take place in the enzymes will be quicker and so will create more of their products. As a general rule of thumb, it has been said that there is a doubling of the rate of reaction for every 10?C rise this is called the ?Q10=2? theory. This should be evident when the concentration of the enzyme and substrate are kept the same also. ??????????? Enzymes are

sensitive to temperature up untill a certain temperature where the shape of the active site is altered drastically, so much so that binding hardly ever takes place. This is called denaturisation. Prediction ??????????? With reference to my theory, I predict that the rate and speed of respiration of glucose by yeast will increase with temperature rise up until a certain point where the enzyme used and secreted by the yeast will become denatured and cease to function, reducing the rate significantly. This is explained through Kinetic theory, yeast respiration and the nature of enzymes. Initial Investigation??????????? In my initial investigation, I simply counted the number of bubbles released by the yeast in a 2 minute period. I did his because I only wanted to uncover the general

trend and temperatures where there was or wasn?t notable activity so I could use this information when conducting my final experiment. I used 1g of glucose and 1g of yeast, creating a 50:50 split, I also used 10cm3 of distilled water. I mixed the three in a boiling tube, warmed it a little and shook it to activate the yeast. I then left it for one minute to let the mixture acclimatise to the temperature and then assembled the apparatus as shown and counted how many bubbles were formed during 2 minutes. My independent variable was the temperature; the dependant being the number of bubbles. I increased the temperature by 10?C each time. I took three readings at each temp took their mean. I timed from the first bubble. Initial Investigation Diagram See Attatched Document Initial

Investigation Results See Attatched Document See Attatched Document ??????????? 0????????????????????????????????? 0????????????????????? 0????????????????????? 0????????????????????? 0 See Attatched Document ??????????? 10??????????????????????????????? 0????????????????????? 0????????????????????? 0????????????????????? 0????????? See Attatched Document ??????????? 20??????????????????????????????? 4????????????????????? 6????????????????????? 4????????????????????? 4.7 ??????????? ??????????? 30??????????????????????????????? 11??????????????????? 9????????????????????? 10??????????????????? 10 ??????????? 40??????????????????????????????? 18??????????????????? 16??????????????????? 14??????????????????? 16 ??????????? 50??????????????????????????????? 22???????????????????

20??????????????????? 19??????????????????? 20.3 See Attatched Document ??????????? 60??????????????????????????????? 4????????????????????? 10??????????????????? 6????????????????????? 5 See Attatched Document At this last temperature, I think the 10 bubbles at 60?C was an anomalous result. This may be due to improper heating and will be discussed in my evaluation. It was not included in my mean number of bubbles. See Attatched Document Graph Variables??????????? In my main experiment, I shall use the time taken for methylene blue test tube with yeast and glucose solution to turn the colour of the control as my dependant variable and the temperature as my independent variable. ??????????? Here is a list of variables that can have an affect on my experiment and also how I will

control them if possible.Temperature Amount of methylene blue Amount of yeast Amount of glucose Volume of water Amount of shaking and acclimatisation Light and atmospheric conditionsTEMPERATURE??????????? Temperature of the experiment will have a great affect on the results as explained by kinetic theory. Temperature will affect the rate of yeast respiration. I shall keep the temperature of he mixture and water bath under control by using a thermometer and checking it constantly. I shall also keep swirling the thermometer to keep the heat distributed. Also, as it will take longer for the temperature inside the test tube the same as the water bath, I shall leave the apparatus for two minutes, keeping the temperature constant.AMOUNT OF METHYLENE BLUE??????????? Methylene blue is