effect of ph on amylase

• What is the first step in the practical procedure?

  Place one drop of iodine solution
• What solutions are combined in the first test tube?

  Starch solution, amylase solution, pH 5 buffer
• What is the volume of each solution in the test tube?

  2 cm cubed
• At what temperature should the water bath be set?

  30 degrees Celsius
• How long should the solutions be left in the water bath?

  10 minutes
• What should be done after the solutions reach the correct temperature?

  Combine the three solutions into one test tube
• What is used to mix the solutions?

  A stirring rod
• What is started when the solutions are combined?

  A stopwatch
• What is done after 30 seconds of mixing?

  Transfer one drop to iodine well
• What indicates the presence of starch in the solution?

  It turns blue-black
• What should be done with the sample every 30 seconds?

  Take a sample until iodine remains orange
• What do we record in the results?

  The time until iodine remains orange
• What should be done after completing the experiment?

  Repeat with different pH buffers
• What is the role of iodine solution in the experiment?

  To test for the presence of starch
• Why is it important to use a water bath?

  To maintain a constant temperature
• How does changing the pH buffer affect the experiment?

  It alters the enzyme activity of amylase
• problems with the practical


  • we are only taking samples every thirty seconds. we only have an approximate time for the reaction to complete.
  • we have to look at the time the iodine turns blue-black which isn't obvious as colour change is gradual.
• how to fix only having an approximate time for reaction to complete 


  we can fix this by taking samples every 10 seconds
• how to get a more precise time to see when iodine turns blue black as its a gradual change


  we can fix this by having several people look at the spotting tile
• what are buffer solution used for


  to control ph