Pepsin converts _________A. Starch into sugarB. Proteins into polypeptidesC. Proteins into amino acidsD. Fats into fatty acids

The correct answer is:

B. Proteins into polypeptides

Explanation:
Pepsin is a digestive enzyme secreted by the stomach. It plays a critical role in breaking down proteins into smaller peptide fragments called polypeptides. Here's how it works:

Production and Activation:

Pepsin is initially secreted by the stomach lining as an inactive precursor called pepsinogen.
In the acidic environment of the stomach (pH ~2, due to hydrochloric acid), pepsinogen is activated into pepsin.
Action:

Pepsin breaks the peptide bonds between amino acids in proteins, producing shorter chains of amino acids called polypeptides.
These polypeptides are further digested into individual amino acids later in the small intestine by other enzymes, such as trypsin and chymotrypsin.
Why other options are incorrect:

A. Starch into sugar: This is the role of amylase, not pepsin.
C. Proteins into amino acids: Pepsin does not break proteins directly into amino acids; it breaks them into polypeptides first.
D. Fats into fatty acids: This is the role of lipase, not pepsin.
Pepsin's function is specific to protein digestion in the stomach.