Outline7 marksChallenge
A student is investigating the effect of pH on the rate of hydrolysis of starch by the enzyme amylase. Starch does not absorb visible light strongly, but it forms a blue-black colour with iodine solution. The student decides to use a colorimeter to monitor the reaction by measuring the disappearance of starch.
Outline how the student could use a colorimeter to measure the rate of starch disappearance in this investigation. In your answer, explain why it is appropriate to measure the rate of substrate disappearance for amylase, and contrast this with an investigation involving catalase, where product formation is measured instead.