The Rate Of Respiration In Yeast And — страница 3

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sensitive to oxygen and will go blue with contact with oxygen and colourless with the production of NADH during glycolysis as the glucose is broken down. The amount of this would affect the accuracy of the readings as the rate of NADH production affects the methylene blue and a differing amount of methylene blue would not give fair and reliable results. I shall keep the amount of drops of methylene blue the same at each timing. AMOUNT OF YEAST??????????? The amount of yeast is crucial, more yeast means more glucose will be respired and more products created. An imbalance will upset the results. The amount of yeast will be weighed out on an accurate top-pan balance each time.AMOUNT OF GLUCOSE??????????? The amount of glucose will affect the results also, as more glucose means that

there are potentially more products, which would make the results accurate or the experiment fair. The glucose will be weighed out each time using an accurate top-pan balance.VOL. OF WATER??????????? The volume of water may have a slight affect to the results as it may cause less accuracy when distributing the heat in the test tube. The volume of water will be kept constant by using a measuring cylinder at each preparation.ACLIMATISATION AND SHAKING??????????? Acclimitisation and shaking will help to activate the yeast and prepare the solution for timing. If it is improperly mixed, acclimatised to temperature or activated, the results would not be fair and inaccurate. I will shake the test tube thoroughly each time until I can see bubbles being created well and I shall do this

while it is warm to aid activation. I shall also leave this in the water bath at the required heat for two minutes, regulating the temperature with the Bunsen.LIGHT + ATMOSPHERIC CONDITIONS??????????? These would not have a great deal of affect on my experiment and are beyond my control. Some of the substances may be sensitive to these, but I doubt they are sensitive enough to affect the results.?Diagram of final experimentApparatus Bunsen Burner Stopwatch Yeast Glucose Stand and Gauze Methylene-blue Syringe Pipette Boiling tubes (x2) Beaker Bungs Method??????????? In my final experiment, I shall use methylene blue in the solution. I shall time how long it takes for methylene blue to go colourless in the solution, constantly checking against a control which contains a little

methylene blue for continuity. To avoid unfair contact to Oxygen in the air, I will? put a layer of oil over the mixture. I shall weigh out 2g of glucose and 2g of yeast this time and 25cm3 of water to aid accuracy.? My independent variable is the temperature and the dependant is the time taken to change colour of control. ??????????? I shall take readings from 20?C to 60?C at 10?C intervals. I will start from 20?C as I found out from my initial investigation that there was no respiration activity below this temperature. I shall proceed in this sequence as it is the easiest way of collecting results and will help to find out other flaws at a lower temp.? Also to aid accuracy, I shall take three readings at each interval and take the mean.Results headingsTime

(s)????????????????????????????????? t1???????? t2???????? t3???????? T(mean)???? Rate (S-1)Temp (?C)????????????????????????????? Safety See Attatched Document HAZARD?????? ?????? DANGER(0-3)?? ? LIKELIHOOD(0-3)???? SCORE???? ACTION See Attatched Document Burn (Bunsen,??????????? 1????????????????????????????????? 2????????????????????????????????? 2????????? ? Goggles, care hot water)?????? ????? ????????????????????????????????????????????????????????????????????????????????????????? ???when heating ??????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? ?? and handling,? ???????????????????????????????? ??????????????????????????????????????????????????????????????????????????????????? ????orange flame

??????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? ?? when not used. See Attatched Document Broken glass????????????? 2????????????????????????????????? 2 ???????????????????????????????? 4????????? ? Goggles, care ??????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? ?? when hot and ??????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? ?handling, clean ??????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? up all fragments Broken ?????????????????????? 3?????????????????????????????????