Question

Among mammals, a significant role in the digestion of milk is played by
A. Rennin
B. Invertase
C. Amylase
D. Intestinal bacteria

Answer 1

Hint: It is a proteolytic enzyme found in gastric juice. It helps to convert the caseinogen into insoluble casein. Casein is the type of protein found in the milk.

Complete answer:
Milk is rich in many nutrients like calcium, fortified vitamin D, etc. The most abundant is casein and whey protein. Milk digestion starts in the stomach where pepsin begins to digest milk’s protein into small components. Milk fats are digested by lingual lipase and finally moves to the small intestine for further digestion.
Rennin is also known as chymosin. It is a protein-digesting enzyme which curdles the milk by converting caseinogen into insoluble casein. Rennin is the only synthesis by some animals by the chief cells of the stomach. It is present only in infants, and starts to decline while growing. It is replaced in effect by secretion of pepsin as a major gastric protease.
Invertase is an enzyme which hydrolysis sucrose into the fructose and glucose. It is chiefly used in candy industries.
Amylase converts polysaccharides to disaccharides. It breaks down the glycosidic bond in the starch and converts complex carbohydrates into simple carbohydrates.
An intestinal bacterium is the microbes found in the gut or intestinal tract. It plays an important role in defending against the pathogen. They fully colonised the spaces and secreted the compound that kills the pathogens.

Therefore the rennin plays a major role in digestion of milk. So the correct answer is option A.

Note: Rennin is only found in cud-chewing animals like cow, goat, etc. The animals that lack rennin, the milk are digested by the action of pepsin as human. The milk is coagulated by the pepsin. A commercial form of rennin is used to make cheese and other products.