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Investigating how prolonged exposure to its optimum temperature affects the respiration of yeast.

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Introduction

Investigating how prolonged exposure to its optimum temperature affects the respiration of yeast. By Stuart Laverty Contents Page(s) * Aims and Hypothesis .............................................. 3-5 * Method .................................................................. 5-11 o Risk Assessment of Equipment ...................... 5 o Justification of Equipment ............................. 6-7 o Full Equipment List ....................................... 7 o Constant Values ........................................... 7-8 o Variables ...................................................... 8 o Pilot Method ................................................. 8-10 o Main Method ................................................ 11 * Results ................................................................... 12-13 o Results for Pilot Method ................................. 12 o Results for Main Method ................................. 13 * Conclusion ............................................................. 14-15 * Evaluation .............................................................. 16-17 * Appendix's ............................................................ 18-21 o Appendix A .................................................. 18 o Appendix B .................................................. 19 o Appendix C .................................................. 20 o Appendix D .................................................. 20 o Appendix E .................................................. 21 * Bibliography .......................................................... 22 * Word Count ........................................................... 22 Investigate how prolonged exposure to its optimum temperature affects the respiration of yeast Aims and Hypothesis:- The aim of this project is to investigate how prolonged exposure to its optimum temperature affects the respiration of yeast. Since yeast is a living organism, it will respire, and is comparable in its characteristics to fungi. Hence, it is classified as being in the Fungi-kingdom. This automatically refers to it as a eukaryotic organism, meaning it has mitochondria - the site of aerobic respiration and the production on ATP (adenosine triphosphate). ATP is the energy for all known living organisms, including fungi like yeast. Yeast uses organic compounds as a source of energy, and therefore do not require sunlight to grow. Instead, it receives its main source of carbon from hexose sugars, with prime examples being glucose and fructose. As with all substances, glucose contains carbon, and is digestible by yeast. Proof that glucose contains carbon can be shown by its chemical structure (see, right) which shows a representation of powdered glucose that I will use in my experiment: The fact that yeast respires using carbon gained from glucose makes it able for practical use, such as bread making and alcohol production. ...read more.

Middle

3. Fill one 1000 cm� beaker with cold water up to around the 700 cm� mark. 4. Create a water bath at the optimum temperature, whatever the pilot experiment suggested it was. For the sake of this example, the optimum temperature will be taken to be 45�C. Heat the water up with hot water from the kettle, and use the thermometer to measure this. If the temperature goes unintentionally too high, then balance it out with cold water. Get the 45�C as close as possible. 5. Fill the 100 cm� measuring cylinder completely with cold water. Press your palm across the top, and invert it into the 1000 cm� beaker filled with cold water (see Figure 3.2 on page 9). Try to lose as little water as possible from the cylinder. Repeat if unsuccessful. 6. Using the second 100 cm� measuring cylinder, take 25 cm� from your water bath (make sure its still at the desired temperature - if not then raise or lower the temperature accordingly). With this 25 cm�, mix it with the powdered glucose, and stir quickly with the stirring rod. See Figure 3.3 on page 9. 7. Put the yeast into the conical flask, before repeating step six, only substituting the glucose with yeast. See Figure 3.4 on page 9. 8. Put the conical flask carefully in the water bath and add the glucose to the yeast mixture and quickly put the bung on the conical flask to seal it up. Start the stopwatch for the amount of time to expose the yeast to its optimum temperature. Make sure that the conical flask doesn't get any additional water in it, and making sure the delivery tube stays outside the measuring cylinder. 9. Once the time has expired, reset the stopwatch quickly. Put the delivery tube into the bottom of the inverted measuring cylinder. Restart the stopwatch immediately. 10. Make sure that the temperature of the water bath doesn't drop by heating it with more hot water if it ever goes cooler. ...read more.

Conclusion

30 6.5 8 5.5 6.667 Appendix E: [�]: This shows the calculations for the Spearman Ranking, which would end up helping find the correlation between the average Carbon Dioxide released and the amount of exposure time, so trends could be easily identified in the project. The following data is the calculations used to work out the Spearman Ranking. It is safe to assume this as correct, since the answer always has to be between +1 and -1. Firstly, a table had to be devised, with the following headings: * Carbon Dioxide Released * Exposure Time * Rank One (Carbon Dioxide Released) * Rank Two (Exposure Time) * d * d� Spearman's Ranking would be worked out in terms of P, which is the actual Ranking itself, and indicates the correlation of a set of points, with +1 being a perfect positive correlation, and -1 being a perfect negative correlation. d stands for the difference, between the two ranks, taking the smallest rank from the biggest. The overall formula for working out the Ranking is: This can be interpreted like so: N is the number of results, so in my experiment there were 7. The Sigma of d� is simply the sum of all the d� numbers, and this was then multiplied by six. The sum of d� would be too hard to work out without a table, where it is made very simple. Carbon Dioxide Released Exposure Time Rank One (Carbon Dioxide Released) Rank Two (Exposure Time) d d� 19.83 0 5 1 4 16 26.17 5 7 2 5 25 21.67 10 6 3 3 9 17.83 15 4 4 0 0 14.17 20 3 5 2 4 11.00 25 2 6 4 16 6.667 30 1 7 6 36 Total d� 106 Substituting the values obtained into the formula gives: P = 1 - [(6x106) � 7(7� - 1)] P = 1 - [(636) � 7(48)] P = 1 - [636 � 336] P = 1 - 1.8929 P = - 0. ...read more.

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