Describe6 marksChallenge
A student investigated the effect of pH on the activity of salivary amylase using a colorimeter. Reaction mixtures containing starch, amylase, and iodine solution were set up at pH 5, 6, 7, and 8. The colorimeter measured the absorbance of light at 30-second intervals. A higher absorbance indicates more starch-iodine complex present. The results are shown in the table below.
| Time (s) | Absorbance at pH 5 | Absorbance at pH 6 | Absorbance at pH 7 | Absorbance at pH 8 |
|---|---|---|---|---|
| 0 | 0.85 | 0.85 | 0.85 | 0.85 |
| 30 | 0.78 | 0.70 | 0.60 | 0.75 |
| 60 | 0.72 | 0.55 | 0.35 | 0.68 |
| 90 | 0.68 | 0.42 | 0.15 | 0.62 |
| 120 | 0.65 | 0.30 | 0.05 | 0.58 |
Describe how the colorimeter is used to obtain these results, and describe what the results indicate about the effect of pH on the rate of amylase activity. Also describe the mechanism by which amylase catalyses the breakdown of starch, including an explanation of enzyme specificity.