Required Practical 5: Effect of pH on Amylase

• Amylase turns starch solution into simple sugars.
• What solution is placed in each well of a spotting tile?

  Iodine solution
• How much starch solution is added to the first test tube?

  2 cm cubed
• What is added to the second test tube?

  2 cm cubed of amylase solution
• What solution is added to the third test tube?

  pH 5 buffer solution
• What temperature is the water bath set to during the experiment?

  30 degrees Celsius
• How long are the test tubes left in the water bath?

  10 minutes
• What should be done after combining all three solutions?

  Mix with a stirring rod
• What is started after returning the combined solution to the water bath?

  A stopwatch
• How often should a drop of solution be taken to test with iodine?

  Every 30 seconds
• What color does iodine turn when starch is present?

  Blue/black
• What does it mean when the iodine remains orange?

  No starch is present
• What should be recorded at the end of the experiment?

  The time for the reaction to complete
• What should be done after completing the first experiment?

  Repeat with different pH buffers
• What is the procedure for testing the effect of pH on amylase activity?

  1. Place iodine in spotting tile.
  2. Prepare three test tubes with:

  • 2 cm cubed starch solution
  • 2 cm cubed amylase solution
  • pH 5 buffer solution

  1. Incubate in a 30°C water bath for 10 minutes.
  2. Combine solutions and mix.
  3. Start stopwatch and test with iodine every 30 seconds.
  4. Record time until iodine remains orange.
  5. Repeat with pH buffers 6, 7, and 8.
• Why are buffer solutons used in biology?

  To control pH levels.
• Why do we leave the test tubes in the water bath for 10 minutes?


  To allow the solutions to reach the correct temperature.