Question

Perform an Experiment to show that saliva breaks down starch into sugar??

Answer 1

Experiment to show the effect of saliva on starch
Two test tubes were taken and were labeled A and B.
In test tube A one teaspoon full of boiled rice was kept.
In test tube B one teaspoon full of boiled rice which were chewed for 3-5 minutes were kept.
3-4 ml of water was added to both the tubes.
Then 2-3 drops of iodine solution was added to both test tubes A and B.
Observation:
The test tube A shows blue – black colour whereas test tube B does not show this colour.
Conclusion:
Since test tube B has boiled rice which were chewed for 3-5 minutes, the saliva present in mouth has acted upon starch to break down into sugars. So it does not show any colour in presence of iodine solution.
Boiled rice in test tube A has not been exposed to saliva, so starch is present which is indicated by blue-black colour on addition of iodine solution.
Tongue
Tongue is a fleshy muscular organ which is free at its front end and is attached at the back of the floor of buccal cavity.
It can move in all directions.
Functions:
It mixes saliva with food while chewing.
It plays an important role while talking.
The taste of the food can be known due to different taste buds present in our tongue.
It helps in swallowing our food.

Answer 2

What experiment do you perform to understand action of saliva on flour? Explain it’s procedure and apparatus that you followed.
A. Experiment to understand action of saliva on flour.
Aim : To demonstrate the action of saliva on flour.
Apparatus : Test tubes (2), flour, watch glass, dilute tincture iodine, saliva (1 teaspoonful)
Procedure:

Take a test tube half-filled with water and add a pinch of flour to it.

Shake the test tube well till the flour gets mixed.

Take a few drops of this mixture in a watch glass and test for the presence of starch by putting a drop of dilute tincture iodine in it.

A blue-black colour confirms the presence of starch.

Now again dissolve a pinch of flour into half-filled water in a test tube.

Now divide the mixture into two equal halves by transferring it to another test tube.

Note that both the test tubes have the same amount of solution.

Add a teaspoon of saliva to one of the test tube and mark it.

Do not add anything in the other test tube.

After sometime (45 minutes) add a drop of dilute tincture iodine solution to test tubes containing the solution.
Observation :

The solution of the test tube to which saliva is added shows colour change as starch is converted to sugar.

There is no colour change in the other test tube to which saliva is not added. Inference
result:
The enzyme amylase in the saliva breaks down the starch molecules into smaller subunits usually into sugars.

hope it helps