AQA practicals – Effect of pH on enzyme reaction rate

Investigate the effect of pH on the rate of reaction of amylase enzyme.

Students should use a continuous sampling technique to determine the time taken to completely digest a starch solution at a range of pH values.
Iodine reagent is to be used to test for starch every 30 seconds.
Temperature must be controlled by use of a water bath or electric heater.

Use appropriate apparatus to record the volumes of liquids, time and pH.
Safe use of a water bath or electric heater.
Measure the rate of reaction by the colour change of iodine indicator.
Use of qualitative iodine reagent to identify starch by continuous sampling.

Use scientific theories and explanations and hypothesis on how pH affects amylase activity.
Carry out experiments appropriately having due regard for the correct manipulation of apparatus, the accuracy of measurements, and health and safety.
Describe the appropriate sampling technique to ensure samples are representative.
Make and record observations and measurements of time.
Present a graph of amylase activity against pH.
Translate numeric data into graphical form.
Carry out rate calculations for chemical reactions.

Typical questions