Question

Assertion
Fat is digested in the intestine by emulsification.
Reason
Bile salts stabilize the emulsion so formed.
(A) Both Assertion and Reason are correct and reason is the correct explanation for Assertion.
(B) Both Assertion and Reason are correct but reason is not the correct explanation for Assertion.
(C) Assertion is correct but Reason is incorrect.
(D) Assertion is incorrect but Reason is correct.

Answer 1

Hint: We need to know what emulsification is and how it plays a role in human digestion. Emulsification is the process of breaking down fats into smaller molecules and an emulsion is a mixture of two or more liquids that are normally immiscible. Digestion is greatly aided by emulsification, the breaking up of fat globules into much smaller emulsion particles or droplets.

Complete answer:
Key points to study emulsification as a process of food digestion are as follows:
The digestion of lipids by emulsification is a form of chemical digestion since enzymes are involved for breaking down of lipids, a type of essential nutrients, to be absorbed for energy.
The digestion of lipids or fats begins in the stomach with the aid of lipases.
Lipids (fats) are digested mainly in the small intestine by bile salts through the process of emulsification, which allows lipases to divide lipids into fatty acids and monoglycerides.
Lipids are hydrophobic in nature. Bile which contains bile salts, have both hydrophobic and hydrophilic sides. The hydrophilic side can interacts with water, while the hydrophobic side interacts with lipids, thereby emulsifying large lipid globules into small lipid globules.
Lipases break down the lipids into fatty acids and glycerides called emulsion droplets which can pass through the plasma membrane of the cell, entering the epithelial cells of the intestinal lining where bile salts are present.
The bile salts being both hydrophobic and hydrophilic in nature surround these fatty acids and glycerides forming micelles (tiny spheres) which prevents the emulsion droplets from reassociating.
These micelles move to the borders of the small intestine where the fatty acids and glycerides are absorbed by the cells of the walls of the small intestine leaving the coated bile salts behind.
     As given in the question, the assertion statement states that Fat is digested in the intestine by emulsification. This holds true as fats or lipids are a part of chemical food digestion which is greatly aided by emulsification. One of the major roles in the emulsification of fats is played by bile salts which do not allow the re-association of the emulsion droplets formed, thereby stabilizing them. Hence the reason statement in the problem question given which states that Bile salts stabilize the emulsion so formed is also correct.
Hence, the correct option is option (A).

Note:
It must be noted that understanding the process of digestion and where digestion of different nutrients such as carbohydrates, lipids, proteins and vitamins takes place is important. Some nutrients get digested in multiple organs such as carbohydrates where its digestion begins in the mouth followed by duodenum. The enzymes involved in the digestion and what role does each of them play is the key.