Effect of Amylase on Starch


Materials


dilute starch solution
250 mL beaker with 150 mL water at 37oC ± 2oC
amylase
5 test tubes and rack
thermometer
dilute hydrochloric acid (HCl)
water bath
Benedict's solution
iodine solution

Procedure

1. Set up the water bath and get the water boiling.

2. label 5 test tubes IC (iodine control), IS (iodine, saliva), ISA (iodine, saliva, acid), BC (Benedict's control), BS (Benedict's, saliva)

Prepare the test tubes as described in the table below:

Test tube amylase starch HCl iodine Benedict's initial color final color
IC - 10 mL - 2 drops      
IS 2 mL 10 mL - 2 drops      
ISA 2 mL 10 mL 1 drop 2 drops      
BC - 10 mL - - 5 drops    
BS 2 mL 10 mL - - 5 drops    

3. Place the test tubes in the 37oC water bath for 10 minutes. Record your results.

4. After 10 min remove test tubes BC and BS and place them in the boiling water bath. Record any color change up to 5 min.



Questions

1. What is the significance of each test tube?

2. a) What substance disappears from the starch/amylase mixture?
b) What new substance appears in the starch/amylase mixture?

3. What is the effect of amylase on starch?

4. What is the effect of the HCl on the amylase/starch solution?

5. Why are tubes IC and BC needed in this experiment?

6. Design a simple experiment that would show if the amylase is used up during starch digestion.

7. Why is it not surprising that carnivores like dogs and cats have no amylase in their saliva?

8. How could a plant make use of an enzyme like amylase?

9. Predict the result if 8 mL of starch and 2 mL of amylase were placed in a dialysis tubing bag and immersed in water as in the Importance of Chemical Digestion Lab.