Yeast Investigation

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Yeast Investigation Introduction In this investigation I am going to try and find the optimum temperature at which the new strain of yeast respires using trial and improvement. I will test from 20°c to 70°c as this is the most suitable. This means that little heating will be needed to get the maximum respiration in the yeast and therefore the most efficient alcohol production. Yeast respires glucose an aerobically producing carbon dioxide and ethanol as waste products. The carbon dioxide is given off as bubbles and the number given off in a certain amount of time can be used to estimate the rate of reaction. I will be using this method in my experiment. Method To do this investigation I will test the yeast in a water bath (beaker filled with water of a certain temperature) so I can adjust the temperature and mix the yeast with water using a syringe and some tubing. I will be using 250ml of water, 25g of sucrose (sugar) and 2g of dried yeast. I will also use tin foil wrapped round the beaker to keep the temperature from changing. Fair Test I will make this experiment a fair test by using the same water bath syringe and tubing each time and by measuring the water sucrose and yeast very carefully. Prediction I predict that the optimum temperature will be around 20°c as yeast respires glucose an aerobically and a higher temperature will speed up the reaction but if the temperature is too high then the reaction will be slowed down. Apparatus Preliminary work I did a preliminary test in order to help me plan my experiment out more carefully and so I can get an idea of what's going to happen. I tested the yeast in temperatures of 20°c and 70°c (the range that I will be testing in in my final experiment). Preliminary Results Temperature tested Bubbles counted 20°c 15 70°c
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