5.6 practical: investigate the role of anaerobic respiration by yeast in different conditions

Method:

- mix sugar, yeast, and distilled water in a boiling tube, covered with a layer of oil to prevent oxygen entry.
- the boiling tube is connected to a second tube of water using bungs to stop oxygen from getting in, so the yeast will have to start respiring anaerobically.
- place the boiling tube in a water bath at a set temperature.
- calculate the rate of CO2 production by dividing the number of bubbles produced by the time taken for them to be produced in seconds. This gives an indication of respiration rate
- repeat the experiment with the water bath set at different temperatures, and compare the results.

Results:
- Rate of CO2 production increases as the temperature gets closer to the optimum, as it will promote increasing enzyme activity which increases anaerobic respiration.
- However, if the temperature is too high, enzymes may denature and the rate of CO2 production will decrease.