Amylase is an enzyme that digests starch. A student investigated the effect of pH on the activity of amylase.
This is the method used.
1.
Mix amylase solution and starch suspension in a boiling tube.
2.
Put the boiling tube into a water bath at 25°C.
Remove a drop of the mixture every 30 seconds and test it for the presence of
starch.
3.
4.
Repeat the investigation at different pH values.
The table below shows the students' results.
PH
Time when no starch was
detected in minutes
5.0
7.0
5.5
4.5
6.0
3.0
2.0
6.5
7.0
1.5
7.5
1.5
8.0
2.0
(a)
The student concluded pH 7.25 was the optimum pH for the amylase enzyme
This is not a valid conclusion.
Suggest two reasons why.​