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Experiments with yeast - 1

To show the effects of temperature on fermentation by yeast

Background information

If yeast is added to a liquid containing sugar and other nutrients, kept at an appropriate temperature [and deprived of oxygen], it will turn the sugars into ethanol (alcohol) and carbon dioxide.
{italics: experimental variables}

Suggested action

Each group to work as a team.

Individually, think about the problem and try to come up with a hypothesis about the effect of temperature on carbon dioxide production by yeast.

Try 1 spatula of yeast per 50 ml of grape juice in a 100ml conical flask, fitted with a bung carrying a delivery tube.....

Decisions needed:

1) How to measure carbon dioxide output - many methods are not practical on the time scale or not available due to other limitations (advice is available)

2) Varying temperature
- what range of temperature is sensible to investigate?
- what actual values of temperature to choose - how many temperatures?
- what method of temperature control?

3) What factors are to be kept constant (and how) ?

4) How to organise team work to gather results.
The same criteria apply to this as to other assessments, so it is important to research and justify each stage.

Results format

Time Elapsed
time from
volume at
Reading taken by (name) :
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