Question

What experiment should you perform to understand action of saliva on flour? Explain its procedure and apparatus that you followed.

Accepted Answer

Aim of the experiment- To understand the action of saliva on flour.
Apparatus required- Test tubes, watch glass, dropper.
Materials required- flour, water, tincture of Iodine.
Procedure-
a) Take a test tube and fill it half with water. Dissolve a pinch of flour in it.
b) Divide the water into two equal parts in separate test tubes.
c) Mark them A and B.
d) Add a teaspoon of saliva in test tube A and nothing in test tube B. Leave the test tube undisturbed for about 45 minutes.

e) After 45 minutes, add a drop of tincture of iodine to both the test tubes.

Observation-
It is observed that the solution in test tube B turns deep blue-black whereas the test tube A solution is yellowish.
Explanation-
The flour solution contains starch. On addition of tincture of iodine, the solution in test tube B readily gives a blue-black colour. When saliva is added in test tube A and left undisturbed for some time, the salivary amylase present in the saliva breaks down the starch present in the solution to simpler carbohydrates. Since starch is no longer present, hence the solution does not give a blue-black colour.
Result- This shows the action of salivary amylase on flour.

List A	List B
(i) Pepsin	a. Carbohydrates
(ii) Amylase	b. Proteins
(iii) Lipase	c. Fats

What experiment should you perform to understand action of saliva on flour? Explain its procedure and apparatus that you followed.

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