Yeast cells produce ethanol (alcohol) in a process called fermentation - Leaving Cert Biology - Question 7 - 2004
Question 7
Yeast cells produce ethanol (alcohol) in a process called fermentation.
Is this process affected by temperature? Explain your answer.
Answer the following in relat... show full transcript
Worked Solution & Example Answer:Yeast cells produce ethanol (alcohol) in a process called fermentation - Leaving Cert Biology - Question 7 - 2004
Step 1
Is this process affected by temperature? Explain your answer.
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Answer
Yes, the process of fermentation is affected by temperature. Enzymatic reactions, including fermentation, typically follow the principle that higher temperatures increase the rate of reaction up to a certain point. Beyond the optimal temperature, the enzymes can denature, leading to a decrease in reaction efficiency.
Step 2
Draw a labelled diagram of the apparatus that you used.
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Answer
A diagram should include:
A fermentation vessel (like a flask)
An airlock to ensure anaerobic conditions
Tubing leading to a collection jar to capture produced gases or liquids
Labels indicating key components like 'yeast', 'sugar', and 'carbon dioxide'.
Step 3
Name a substance that yeast can use to make ethanol.
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Yeast can use sugars, such as glucose or sucrose, to produce ethanol during fermentation.
Step 4
What substance, other than ethanol, is produced during fermentation?
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Carbon dioxide is another product of fermentation, along with ethanol.
Step 5
Describe the control that you used in this experiment.
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A control setup could involve performing the fermentation with the same conditions but without yeast to ensure that any produced ethanol is due to yeast activity.
Step 6
Explain the purpose of a control in a scientific experiment.
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The purpose of a control in a scientific experiment is to provide a baseline for comparison. It helps to validate that the results obtained from the experimental groups are due to the variable being tested and not other external factors.
Step 7
How did you know when the fermentation was finished?
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The fermentation process can be determined to be finished when there is no further gas production, commonly evidenced by a lack of bubbles in the fermentation vessel or when there are no changes in the liquid's density.
Step 8
Why were solutions of potassium iodide and sodium hypochlorite added to the reaction vessels after a certain period of time?
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Potassium iodide and sodium hypochlorite solutions were added to test for the presence of starch and reduce microbial contamination. They help ensure that any changes observed in the experiment are due to the fermentation process rather than external influences.
Step 9
Name a substance produced during aerobic respiration that is not produced during fermentation.
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Water is a substance produced during aerobic respiration that is not produced during fermentation.
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