Effect Of pH On Rate Of Reaction Of Amylase Required Practical

Question 1

Independent variable

Answer 1

pH

Question 2

Dependent variable

Answer 2

Rate of reaction

Question 3

Control variables

Answer 3

• temperature
• same concentration amylase
• same concentration starch
• same volume of starch and amylase in buffer solution
• same temperature - using an electric water bath

Question 4

Method

Answer 4

1. Use the syringe to place 2 cm of amylase solution into a test tube.
2. Use another syringe to add 1 cm of pH buffer solution to the test tube.
3. Place the test tube into a water bath set at 30 °C and leave for 5 minutes.
4. Whilst waiting, add a drop of iodine solution into each dimple of a spotting tile.
5. After 5 minutes, use another syringe to add 2 cm of starch to the amylase/buffer solution, start the stop clock and leave it on throughout the test. Mix using a plastic pipette.
6. Remove a drop of amylase/starch/buffer mixture after 30 seconds and add to the first drop of iodine on your spotting tile.
7. Wait another 30 seconds. Then remove a second drop of the mixture to add to the next drop of iodine.
8. Repeat step 6 until the iodine solution and the amylase/buffer/starch mixture remains orange.
9. Record the time taken for the amylase to fully digest the starch, using a pencil.
10. Repeat the whole procedure with a different pH buffer.

Question 5

What is a buffer solution?

Answer 5

A solution which resists changes in pH

Question 6

Safety

Answer 6

• Always wear safety goggles
• Take care of boiling water (if using Bunsen burner)

Question 7

Common mistakes to avoid

Answer 7

• Always ensure you’ve set up correctly before you begin so that you can test the amylase starch solution every 30 seconds without delay
• Avoid cross-contamination by making sure you use a different pipette for different solutions