Question

1. in humans, initial digestion of proteins begins where?

a. mouth
b. jejunum
c. ileum
d. stomach
e. none of these are correct

Explanation:

The initial digestion of proteins in humans begins in the stomach. In the stomach, hydrochloric acid denatures proteins, and pepsin (an enzyme) starts breaking down the peptide bonds in proteins. The mouth is mainly for carbohydrate digestion (e.g., salivary amylase acts on starches). The jejunum and ileum are parts of the small intestine where further digestion (by pancreatic enzymes like trypsin and chymotrypsin) and absorption of amino acids (the end - products of protein digestion) occur. Since the stomach is where the initial protein digestion happens, option d is correct.

Answer:

d. stomach