Question

How to test the presence of starch in a given food item and action of saliva?

Answer 1

The presence of starch in a food item can be tested by adding few drops of dilute iodine solution to it. There will be a colour change when iodine solution is added to starch.

ACTIVITY TO SHOW THE ROLE OF SALIVA

take 1 ml starch solution in 2 test tubes{A and B}

add 1 ml of saliva to test tube A and leave both the test tubes undisturbed for 20-30 minutes

now add a few drops of dilute iodine solution to the test tubes.

there is a colour change in test tube B but not in test tube A.

This indicates that saliva has broken down the starch in the test tube A.