The enzyme amylase breaks down starch into simple sugars. A student investigated the effect of pH on the activity of amylase. To do this, the
student varied the pH by using different pH buffer solutions and added
each buffer to equal volumes of amylase and starch solutions. Every 30
seconds a drop of the mixture was tested for starch using iodine that had
been dropped into wells in a dimple tray. Iodine turns blue/black if starch is
still present. The time taken for the lodine to no longer turn blue/black was
recorded for each pH tested. The results can be seen below. State the pH
at which the rate of reaction was greatest. Explain your answer
pH Buffer used Time taken for iodine to no longer turn blue/black (s)
4
120
6
60
8
150
10
Always turned blue/black