Question

In the stomach, X converts an inactive enzyme into Y, which acts on the food to provide Z. Identify X, Y, and Z.

• A. X – HCl; Y – Pepsinogen; Z – Peptide
• B. X – HCl; Y – Pepsin; Z – Peptide
• C. X – Rennin; Y – HCl; Z – Pepsin
• D. None of the above

Answer 1

The correct option is B X – HCl; Y – Pepsin; Z – Peptide

X is HCl, which activates the inactive enzyme pepsinogen. Y is the active enzyme, pepsin, which acts on protein to break it down into peptides (Z).
In infants, prorennin is an enzyme similar to pepsinogen that is activated in a similar way to pepsin. Rennin, which is an active form of prorennin digests proteins in infants’ diets.