Question

take 1 ml of starch solution in two test tubes A and B. Add 1ml saliva to the test tube A and leave both test tubes undisturbed for 20 to 30 minutes now add a few drops of delute iodine solution to the test tubes. In which test tube you will observe a colour change. what does this tell about the action of the saliva on the starch

Answer 1

The activity of saliva on starch

1. 1ml of 1% starch was taken in two test tubes A and B.

2. 1ml of saliva was added to the test tube A only.

3. The test tubes were left aside for 30 minutes.

4. Dilute Iodine solution was added to the test tube.

5. In test tube A, the Iodine solution color remained the same which indicates the absence of starch.

6. In test tube B, the Solution turns into a black due to the presence of Starch.

Result: the presence of saliva in the test tube A acts on starch and broke them down.

In test tube B, the starch was not broken down due to the absence of the saliva.

Answer 2

1) What does this indicate about the presence of a absence of starch in the two test tubes

Explanation:

The starch is absent in test tube A as it is mixed with saliva. saliva breaks down the starch into simple form . Hence , In test tube B the absence of saliva turned the iodine solution to blue black colour thus it indicates the presence of starch

2) What does it tell us about the action of saliva on starch ?

Explanation:

The presence of saliva in test tube A turned the starch into simple sugar which means that saliva reacts with starch in our mouth to form simple sugars ...

Hope it helps u