Question

The initial step in the digestion of milk in humans is carried out by?

• A. Pepsin
• B. Trypsin
• C. Rennin
• D. Lipase

Answer 1

The correct option is A

Pepsin

The correct option is A.

Explanation of the correct option:

1. The chief cells of the stomach release pepsin.
2. It helps in the digestion of proteins by breaking down proteins into smaller peptides in the stomach.
3. The first stage of milk digestion begins in the stomach, where pepsin and other proteases break down the milk's proteins.
4. As milk is gulped down rather than swallowed, the fat and carbohydrates in it will not be broken down in the mouth, therefore neither amylase nor lipase will function.
5. Pepsin is an enzyme found in the stomach of humans that breaks down milk proteins.
6. Rennin is present in calves. Infant humans also have trace levels of rennin, but not adults.
7. Water-soluble caseinogen (milk protein) is affected by pepsin to produce soluble "casein."

Explanation of the incorrect options:

Option B:

Trypsin in the small intestine helps in the digestion of proteins.

Option C:

1. Rennin is also known as chymosin.
2. It converts caseinogen into insoluble casein.
3. It is found in the gastric juice of infants.

Option D:

Lipase enzyme helps in the digestion of fats so that they can be easily absorbed in the small intestine.

Final answer:

The initial step in the digestion of milk in humans is carried out by pepsin.