GCSE Biology Required Practical: Enzyme Rates of Reaction
Contents
Key Stage 4
Meaning
Investigate the effect of pH on the rate of reaction for an enzyme.
Experiment Version 1
Variables
- Independent Variable - pH of the buffered pH solution.
- Dependent Variable - Time taken for the colour change to take place.
- Control Variables - The temperature of all solutions. The volume of all solutions.
Method
- Place test tubes containing a range of of pH buffer solutions, a container of starch solution and a container of amylase solution in a water bath at a temperature of around 30°C and wait until all solutions reach that temperature.
- Use a pipette to place one drop of Iodine Solution into each depression in a spotting tile.
- Use a clean pipette or syringe to place 2cm3 of each pH buffer into a test tube.
- Use a clean pipette or syringe to place 2cm3 of starch solution into the same test tube.
- Use a clean pipette or syringe to place 1cm3 of amylase solution into the same test tube and start the stopwatch.
- Use a clean pipette to remove a drop of the solution form the test tube and drop it on the spotting tile every 10 seconds, beginning at 0 seconds.
- Repeat this until the iodine solution in one of the depressions no longer turns black, but instead remains orange.
- Repeat steps 2 to 7 until all different pH buffers have been tested.
- Plot a graph with pH on the x-axis and time taken on the y-axis.