Question

observe the given diagram:
Few drops of dilute iodine solution is added to both the test tubes. Blue colour appears in the test tube 'B'. what change occurs in test tube 'A' ? why?​

Answer 1

Answer:

The colour of the test tube A does not changes

because crushed potatoes with saliva means that-it is a chewed potatoe as saliva is present

• the saliva will break the starch present in potatoe into simple sugars at it contains enzyme salivary amylase
• as there is no starch present in crushed potatoe the dilute iodine solution does not act on it and hence there is no colour change
• but in test tube B as there is no saliva there is no breakdown of starch
• dilute iodine solution reacts with starch and turn into blue colour

Answer 2

The test B contains potato that is rich in starch and When iodine reacts with starch it gives blue color.

Explanation:

• The color of the test tube a does not change as it contains alive in it.
• Saliva contains salivary amylase enzyme that does break the proteins and carbohydrates into smaller units.
• While the test B contains potato that is rich in starch and When iodine reacts with starch it gives blue color.
• But saliva does not contain starch therefore its color remains unchanged.