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NCERT Solutions Curiosity Chapter 9 .1.1 Digestion in human beings — In-text Questions

Book page 1239 Updated on2026-09-05

Q1.
What do you think is the role of saliva in your mouth? What do you feel when you eat other types of food, such as chapati?
Answer

Saliva has two roles in the mouth:

  1. It moistens the food. The tongue mixes chewed food with saliva, making it soft and slippery so that it is easy to swallow and can slide down the food pipe.
  2. It begins digestion. Saliva contains a digestive juice that breaks down starch into sugar.

When you eat a chapati, at first it tastes like an ordinary chapati. But if you keep it in the mouth and chew it for 30–60 seconds, it begins to taste sweet.

Why it happens: chapati contains starch, a type of carbohydrate. Starch itself has no sweet taste. The digestive juice in saliva breaks the starch into sugar, and sugar tastes sweet — so the longer you chew, the sweeter the chapati tastes.
Q2.
Take a small piece of chapati or a bite-sized portion of boiled rice and chew it properly for 30–60 seconds. At first, the chapati or rice has its usual taste, but as you continue chewing, do you notice a change in taste? The food begins to taste sweet! Have you ever wondered why this happens?
Answer

Yes — the taste changes. The chapati or rice slowly begins to taste sweet as you keep chewing.

Chapati / boiled rice → contains starch (a carbohydrate) — not sweet
Starch + digestive juice of saliva → sugar — sweet
So: longer chewing → more starch changed to sugar → sweeter taste
Why it happens: saliva is not just water. It carries a digestive juice that acts on starch and breaks it into simple sugar. Digestion of starch therefore begins in the mouth itself, not in the stomach.
Try This: chew a piece of chapati for only 5 seconds and note the taste, then chew a fresh piece for a full minute. The difference is easy to notice, and it is proof that saliva is working.
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