Question

Boojho took some grains of boiled rice in test tube ‘A’ and
Paheli took boiled and chewed rice in test tube ‘B’. Both of
them poured 1 – 2 drops of iodine solution into the test tube
and observed the colour change. What colour change would
they have observed? Give reasons for your answer.
NCERT Class VIII
Science - Exemplar Problems
Chapter 2. Nutrition in Animals

Answer 1

The color change must be observed in the testube where the boiled and chewed rice is Blue because it forms as starch and when iodine reacts with starch solution it turns blue in colour .

Answer 2

Answer:

Tube A and Tube B turns dark blue colour.

Explanation:

• The presence of starch turns the solution in the test tube into blue colour in the boiled rice.
• After adding iodine to it the colour never changes as the activity of salivary amylase on starch.
• The conversion of starch present in salivary amylase into maltose gives a negative reaction.
• Thus, the colour change is prominently noted. In other reactions, this colour difference is not seen much.