Question

Take 1 mL starch solution (1%) in two test tubes (A and B).
Add 1 ml saliva to test tube A and leave both test tubes undisturbed
for 20-30 minutes.
Now add a few drops of dilute lodine solution to the test tubes.
In which test tube do you observe a colour change?
What does this indicate about the presence or absence of starch
in the two test tubes?
What does this tell us about the action of saliva on starch?​

Answer 1

Answer:

We will observe a colour change in test tube-B

Addition of iodine will give a purple-blue colour.This colour is due to the presence of starch in test tube B.

No colour is seen in test tube A since saliva contains salivary amylase enzyme which digests starch.