CAIE A Level Biology 9700 · Enzymes
A student investigated the hydrolysis of starch by amylase. A starch solution was mixed with amylase and incubated at 37°C. At 30-second intervals, a sample was removed and added to iodine reagent. The absorbance of each sample was measured using a colorimeter.
| Time / s | Absorbance (arbitrary units) |
|---|---|
| 0 | 0.52 |
| 30 | 0.44 |
| 60 | 0.35 |
| 90 | 0.26 |
| 120 | 0.18 |
| 150 | 0.11 |
| 180 | 0.10 |
| 210 | 0.11 |
Describe the results shown in the table. Explain these results in terms of the mode of action of amylase.
4 marks, so the mark scheme is looking for about 4 separate creditworthy points. Making the same point twice in different words earns it once.
Describe means: Say what happens or what something is like, in order and with detail. You are not being asked why. If there is data, quote it: name the trend, then give figures with units at the points where it changes.
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