Investigating the Rate of Respiration in Yeast: Triple/double science Biology coursework for GCSE - page 2
Keywords: Investigating the Rate of Respiration in Yeast: Triple/double science Biology coursework for GCSE, anerobic respiration, A, Higher Level
By Glamurus on 02/11/2006 17:54:57
Level: GCSE Key Stage 4 (Years 10-11)
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other variables aren’t interfering pr affecting the experiment. Some other things I needed to find out from this preliminary experiment are exactly how to measure the amount of oxygen produced and what temperature all the water used in the experiment should be.
This is my first result:
Glucose concentration (%) : 10
Amount of gas produced in 2 minutes (cm³) : 0
This experiment didn’t produce a result because I used water at room temperature (20°C). Yeast didn’t respire rapidly enough to produce a result at this low temperature. For my second repeat experiment, I used the same concentration of glucose but I increased the water temperature to 30°C.
This is my second result:
Glucose concentration (%) : 10
Amount of gas produced in 2 minutes (cm³) : 3
There are two things that could still be improved in this experiment. I started the stopwatch when the first bubble appeared, but to do so will not measure rate of respiration well. This is because some of this early gas may be air from inside the boiling tube and the gas that is carbon dioxide will be given off unevenly because the yeast will not yet be respiring at a constant rate. Also very little gas was produced in 2 minutes, so I am going to wait 5 minutes for the rate of respiration to become a constant rate, then I am going to time how much carbon dioxide is given off by the yeast respiring for the 5 minutes after that. I am going to use water at 35°C.
Method
1. Set up equipment as shown in diagram above. Check the water temperature (it should be 35°C) by using the thermometer. Put 10cm³ of yeast in the boiling tube, then dilute the glucose accordingly. I am going to use these concentrations:
Solution (cm³) Water (cm³)
10 0
8 2
6 4
4 6
2 8
0 10
2. Put the glucose into the boiling tube, then replace the bung. Start the stopwatch. Wait for 5 minutes.
3. After 5 minutes, note the level of the water in the burette. Wait 5 minutes.
4. After 5 minutes, stop the stopwatch. Note the level of water in the burette. Subtract this from the original reading. This is the volume in cm³ of gas that has been given off by the yeast respiring.
5. Repeat.
I will do 2
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