Name: Digestion in Grass-Eating Animals
Uploaded: 2019-07-19
Duration: 5 min 47 s
Description: Digestion in grass-eating animals involves the process of rumination. In this video, we will learn about the digestive system of ruminants and the importance...

Question

A slice of bread gives a positive iodine test. However, if the slice is thoroughly chewed, the test is negative. Explain giving reasons.

Accepted Answer

Iodine test is used to check the presence of starch in the leaves, food items such as bread, etc. Starch is a carbohydrate and a stored form of glucose in the plants. Iodine solution reacts with starch to give a blue-black coloured complex.

While thoroughly chewing a slice of bread, the salivary amylase acts on the starch present in the bread. It breaks down starch into maltose and dextrin. This is the reason why thoroughly chewed slice of bread gives a negative starch test. A fresh slice of bread will have the starch in the intact form and thus will give a positive iodine test.

A slice of bread gives a positive iodine test. However, if the slice is thoroughly chewed, the test is negative. Explain giving reasons.

Important Questions on Nutrition in Animals

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