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Experiment to show the factors that effect the respiration in yeast

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Experiment to show the factors that effect the respiration in yeast Introduction Yeast is a single celled fungus. It respires anaerobically (the release of energy from glucose, without combining it with oxygen). When this is done it converts sugar to ethanol. Yeast is one of the living cells which can respire without oxygen anaerobically by reacting with a sugar solution such as glucose to produce carbon dioxide and ethanol and a small amount of energy. When the conversion of sugar to ethanol and carbon dioxide it is known as fermentation. The energy formed is necessary for the yeast to carry out the reactions necessary for cell growth. Yeast cell replicates fastest at about forty-two degrees Celsius. The variable I have used to carry out this experiment is Temperature Equation: Glucose -> alcohol + carbon dioxide + energy Prediction I predict that in my bubble count the number of bubbles will increase gradually as the temperature increase up to sixty-two degrees Celsius because the yeast will respire faster at a higher temperature. At 27 degrees Celsius the yeast will give off Carbon dioxide because the temperature is to low and it is not high enough to form a reaction but between 32 degrees Celsius and 47 degrees Celsius a large amount of Carbon Dioxide we be given off. ...read more.


After that you connect the delivery tube to the boiling tube with the rubber bung going into the boiling tube and the glass end going into a test tube. 8. You then start your stop clock and leave it running for 10minutes waiting for the yeast and glucose solution to react and form carbon dioxide which should then form bubbles. 9. You then count the amount of bubbles formed within one minute. 10. When you have completed those following steps you repeated them three times for each temperature. You use these eight different temperatures which are: 27, 32, 37, 42, 47, 52, 57, & 62 degrees Celsius. Diagram to show the method used Results Temperature (degrees Celsius) Carbon Dioxide Bubbles within one minute 1 2 3 Average 27 4 4 5 9.67 32 9 10 10 22.33 37 22 24 25 54.33 42 44 47 48 107.00 47 63 67 70 153.33 52 15 14 17 15.33 57 13 11 14 12.6 62 No Bubbles formed 0 Conclusion Hydrogen Peroxide is broken down by peroxides in many organisms. Its catalytic results in the release of oxygen gas can be collected and is measured. The estimation of the oxygen release can be made by counting bubbles. Equation: 2H2O2 --> 2H2O + O2 Hydrogen Peroxide The experiment uses the peroxides of yeast which is available without destruction of yeast cells. ...read more.


The second to last temperature I tested was 57 degrees Celsius. At this point very few bubbles were formed. The amounts of bubbles formed were similar to the amounts formed at 32 degrees Celsius. The last temperature I tested was 62 degrees Celsius. At this point there were no bubbles formed therefore the yeast had denatured. Evaluation My results may not have been accurate as they should have been because sometimes the amount of bubbles being let of may have been released to fast and therefore they could not have been counted correctly and accurately. Different batches of yeast which were used gave of different results in my experiment. The bubbles which were formed could have either been large or small, therefore the accuracy of my results may have reduced. The Temperature of the climate outside can make my results vary. At different times of the day you can get different results because of the room temperature changing. e.g. Monday morning the experiment takes place, the room temperature is colder. Thursday afternoon the experiment continues, the room temperature is a lot warmer than the Monday morning. The Timings of the experiment done can also effect my results because at different times of the day, the temperature of the yeast can be affected. This shows that errors have occurred. All of the reasons given above evaluate what problems went wrong during my experiment. ?? ?? ?? ?? Rishul Shah 10B ...read more.

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