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Draw a labelled diagram of the apparatus in which you used yeasts to produce alcohol - Leaving Cert Biology - Question c - 2007
Question c
Draw a labelled diagram of the apparatus in which you used yeasts to produce alcohol. The water that you used in the apparatus was previously boiled and cooled. Why... show full transcript
Worked Solution & Example Answer:Draw a labelled diagram of the apparatus in which you used yeasts to produce alcohol - Leaving Cert Biology - Question c - 2007
Step 1
Draw a labelled diagram of the apparatus in which you used yeasts to produce alcohol.
Answer
To represent the apparatus used for alcohol production via yeast fermentation, I would sketch a glass container (fermentation vessel) with the following components:
- Yeast Solution: Represented as a liquid in the container.
- Air Lock: To prevent oxygen entry while allowing carbon dioxide to escape.
- Water Seal: A layer of oil or liquid on top to further exclude air.
It's crucial to label all parts accurately to ensure clarity.
Step 2
The water that you used in the apparatus was previously boiled and cooled. Why was this?
Answer
The water was boiled and cooled to remove oxygen and eliminate any microorganisms that could interfere with the yeast's fermentation process. This step helps in preventing enzyme denaturation and ensures a conducive environment for yeast activity.
Step 3
In your investigation it was necessary to exclude air. How was this done?
Answer
Air was excluded by using an airlock on the fermentation vessel. The airlock allows gas produced during fermentation (carbon dioxide) to escape without letting air in, thereby creating an anaerobic environment essential for yeast activity.
Step 4
Describe briefly a test to show that alcohol had been produced.
Answer
To test for alcohol production, a few drops of the solution can be mixed with a reagent such as potassium dichromate. If alcohol is present, the solution will change color, indicating a positive result for alcohol. Alternatively, warming the solution and adding a small amount of acidified dichromate will also confirm alcohol presence through a color change.