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Many living cells produce hydrogen peroxide as a by-product of some metabolic reactions - VCE - SSCE Biology - Question 3 - 2007 - Paper 1
Question 3
Many living cells produce hydrogen peroxide as a by-product of some metabolic reactions. Hydrogen peroxide is a poisonous substance for these cells and is immediatel... show full transcript
Worked Solution & Example Answer:Many living cells produce hydrogen peroxide as a by-product of some metabolic reactions - VCE - SSCE Biology - Question 3 - 2007 - Paper 1
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b. Do you agree or disagree with the student's prediction? Explain the reason for your choice.
Answer
I disagree with the student’s prediction. While it is true that different organisms can have varying optimal temperatures for enzyme activity, the catalase enzyme in carrots and humans is somewhat similar due to a common evolutionary origin. Since carrots grow in soil temperatures around 16°C, it is expected that the optimal temperature for carrot catalase activity should be closer to this temperature rather than significantly lower; thus, we cannot assume a drastic difference in optimal temperatures between the species.
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c. Describe (or outline) an experiment you would carry out with pieces of carrot to test the accuracy of the student's prediction. Hydrogen peroxide is available as a 3% in water solution. Explain fully what results would support or negate the student's prediction.
Answer
To test the student’s prediction, I would establish an experiment where I prepare several samples of carrot pieces and expose each set to various temperatures (e.g., 10°C, 20°C, 30°C, 37°C, 45°C). I would then add a fixed volume of 3% hydrogen peroxide solution to each sample and measure the rate of oxygen production, which can be done using a graduated cylinder to collect the gas produced.
The experiment should be controlled to ensure that the hydrogen peroxide concentration, volume of carrot pieces, and surface area are kept constant across samples to ensure reliable results.
If my experiment shows that the optimal temperature for carrot catalase activity is around 37°C or similar, it would challenge the student’s prediction. However, if the results indicate that the optimal temperature is significantly lower, it would support the student’s observation.