Question

What is the role of the small intestine in humans?
I. Vitamin synthesis
II. Absorb water
III. Absorb nutrients
A. I & II only
B. II & III only
C. II only
D. I only
E. III only

Answer 1

Small intestine is the organ of the gastro-intestinal tract or the alimentary canal and it serves many important functions which help an organism in its nutrition. It is located between the stomach and the pancreas. The small intestine receives bile and pancreatic fluids. Structurally, it is a tubular organ which also carries a large number of good microbes.

Complete answer:
Option A: This option cannot be correct because the small intestine does not serve the function of absorbing water or synthesizing vitamins.
Thus, this option is not correct.
Option B: This option is correct because it states that the small intestine serves the role of absorbing water and nutrients. In the former role of small intestine passive diffusion of water takes place through the mucosa of the small intestine and the later role is, absorbing nutrients.
Thus, option B is correct.
Option C: This option is also incorrect because the small intestine absorbs water by diffusion but it also absorbs nutrients. Thus the overall option is incorrect.
Thus, this option is incorrect.
Option D: It is also a wrong choice as the small intestine does not synthesize any vitamin.
Thus, this option is incorrect.
Option E: This option is correct because the small intestine of human beings serves the primary function of absorption of nutrients and minerals through its epithelium. But in addition, the small intestine also absorbs water.
Thus, Option E is incorrect.

Hence, Option B is the correct answer.

Note:
The small intestine consists of the duodenum, jejunum, and ileum. Almost all nutrients in food are absorbed into the blood through the villi present in the small intestine. In addition, the intestine absorbs water and electrolytes, so it plays a key role in maintaining the body's water and acid-base balance. Villi are fingerlike projections of the intestinal mucosa which increases surface area for absorption of nutrients.