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Gas Production by Yeast

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Introduction

Gas Production by Yeast. First Experiment Apparatus The apparatus we used in the first experiment are as follows: Syringe, fresh yeast, three solutions of glucose at concentrations of 1%, 5% and 10%, enamel dish, boss head, small crystallising dish, glass rod, spatula, 10cm measuring cylinder, stop clock, thermometers and a water bath. Prediction I predict that as I increase the concentration of glucose, the more bubbles will be produced. Method My partner and I placed one spatula of fresh yeast into a glass beaker, 5cm3 of 1% glucose was added to the beaker slowly bit at a time, my partner and I mixed the two together thoroughly. When the glucose and yeast were mixed together well, we drew 5cm3 of the mixture into a syringe we then made sure that the mixture was not near the nozzle by pulling the plunger back as far as it could go. We both filled a water bath with warm water at a temp of 35oC and placed the syringe in the bath, a boss head was used to hold the syringe down. ...read more.

Middle

Prediction I predict that as I increase the concentration of glucose, the more bubbles will be produced. Apparatus My partner and I, first decided on the apparatus we are going to use and we both came up with the following: Pestle and mortar, one spatula, yeast, syringe, 10ml measuring cylinder, warm water, tub, cork/bung, glucose solutions 1% 5% 10% 15% 20% concentrations, petri dish, thermometer, glass rod. Plan In the experiment we are going to undergo, my partner and I aim to find out how quickly yeast respires with 1% 5% 10% 15% 20% concentrations of glucose. We will find this information out by counting the number of bubbles produced each minute by the yeast. My partner and I can control variables by the amount of water, amount of yeast, time spent in the water bath at a temperature of 35oC and the volume of the glucose. The things that I am going to change from the first experiment are as follows; I am going to raise the syringe while it is in the water bath, I will do this by placing a bung under the syringe, and this will prevent the mixture from leaking out of the end of the syringe. ...read more.

Conclusion

The syringe with the solution in it was placed into the bath, a bung was placed underneath the syringe to make sure the solution does not leak a pestle was then placed on top of the syringe to hold it in place. My partner started the stop-clock and I was waiting to count the bubbles produced, we waited for four minutes. The apparatus was then washed out and the experiment was repeated with 5% 10% 15% 20% concentrations of glucose. Results Glucose solution Number Of Bubbles Produced Each Minute 1st Min 2nd Min 3rd Min 4th Min 5th Min 1% 1 0 0 0 2 5% 4 2 2 2 2 10% 2 1 3 3 2 15% 5 4 2 2 3 20% 3 2 1 1 1 Evaluation The reason my experiment worked this time and not in my first experiment was; I placed a bung underneath the syringe, by doing this my syringe did not leak any mixture, my partner and I also ground down the yeast before mixing the yeast and glucose together. Mt partner and I also used to more solutions of glucose at concentrations of 15% and 20% to make my results more reliable. Rhys Buckley 10f ...read more.

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