Required Practical 1: Enzyme-Controlled Reactions

• 1. Put a drop of iodine in a potassium iodide solution into each well on a spotting tile. Label the wells.
• 2. Mix together a known concentration and volume of amylase and starch in a test tube.
• 3. Use a dropping pipette to put a drop of this mixture into each of the wells containing the iodine solution at regular intervals (every 20 seconds).
• 4. Observe the resulting colour. The iodine solution goes dark blue-black when starch is present but remains browny-orange colour when there's no starch.
• 5. You can see how fast amylase is working by recording how long it takes for the iodine solution to no longer turn blue-black when the starch/amylase mixture is added
• Step 5)

  
• 6. Repeat the experiment using different concentrations of amylase.
• 7. Repeat the experiment 3 times at each amylase concentration and use your results to find the mean time taken
• Apparatus of the practical

  
• Variables

  • investigate the effects of temperature and enzyme concentration on the rate of enzyme-controlled reactions