A-LevelBiologyEnzymes9700/12 · Feb/Mar 2024 · Q131 Mark
A scientist investigated the progress of two enzyme-catalysed reactions in separate test-tubes, X and Y. Both reactions result in colour changes that can be detected using colorimetry. 0.5 cm³ samples were taken from each test-tube at the start of the investigation and at regular intervals for the next 5 minutes. Copper ions were added to each sample as soon as the sample was collected to inactivate the enzymes and stop the reactions from progressing further. The absorbance of each sample was measured using a colorimeter. The graph shows the results of this investigation. [Figure 13.1]
This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.
AThe substrate in test-tube X has a higher absorbance than the product.
BThe product in test-tube Y has a lower absorbance than the substrate.
CThe rate of the reaction in test-tube X increased with time.
DThe rate of the reaction in test-tube Y increased with time.
✓ Correct answer
B: The product in test-tube Y has a lower absorbance than the substrate.
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