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 iodine solution to the test tubes.
In which test tube do you observe a colour change?
✅ Answer: Test tube B.
What does this indicate about the presence or absence of starch in the two test tubes?
✅ Answer: Test tube A does not contain starch whereas test tube B contains starch.
What does this tell us about the action of saliva on starch?