NCERT Solutions Curiosity Chapter 9 .1.1 Digestion in human beings — In-text Questions
Book page 1269 Updated on2026-09-05
Q1.
How are these nutrients absorbed from the small intestine?
Answer
The inner lining of the small intestine is thin and carries thousands of finger-like projections (Fig. 9.5). These projections greatly increase the surface area of the lining. Digested nutrients pass through this thin wall into the blood present in the blood vessels of the wall, and the blood carries them to every part of the body. This passing of nutrients into the blood is called absorption.
The finger-like projections of the small intestine work the way a folded towel soaks up much more water than a flat sheet of paper.
Why it happens: absorption can happen only where the food touches the wall. A smooth tube 6 m long would touch very little food. Thousands of tiny fingers turn the same 6 m into an absorbing surface many times bigger, so almost nothing useful is wasted.
Did you know? This is exactly why celiac disease is so serious. It damages this inner lining, the absorbing surface is lost, and the person stays weak even after eating well.
Q2.
After most of the nutrients are digested and absorbed in the small intestine, what happens to the undigested food?
Answer
It moves on into the large intestine. There:
The large intestine absorbs water and some salts from it, so the watery waste becomes semi-solid.
This semi-solid waste is called stool.
The stool is stored in the rectum, the lower part of the large intestine, until the body is ready to get rid of it.
Finally it is expelled through the anus — a process known as egestion.
Undigested food → large intestine (water + salts absorbed)
→ semi-solid stool → stored in rectum
→ expelled through anus = egestion
Tip: eating fibre-rich food — fruits, vegetables and whole grains — helps the large intestine work properly and makes the stool easier to pass.
Q3.
It is shorter than the small intestine. Then why is it called the large intestine?
Answer
Because it is named for its width, not its length. The large intestine is only about 1.5 m long against the small intestine's 6 m, but it is much wider than the small intestine — and that is why it is called "large".
Feature
Small intestine
Large intestine
Length
about 6 m — the longest part of the canal
about 1.5 m
Width
Narrow
Wider
Main job
Digestion is completed; nutrients are absorbed
Water and some salts are absorbed; stool is formed and stored
Why it happens: the two names describe the bore of the tube, the way we speak of a "large" pipe and a "small" pipe in a house even when the small one runs further.