Question

A 32-year-old male is on a weight-maintenance diet, so he does not want to lose or gain any weight. Which amino acid must be present in the diet so the patient does not go into a negative nitrogen balance?

(A) Alanine
(B) Arginine
(C) Glycine
(D) Threonine
(E) Serine

Answer 1

Threonine is the essential amino acid that must be present in the diet to prevent a negative nitrogen balance, as the body cannot synthesize it and it must be obtained from food.

Step-by-step explanation:

The amino acid that must be present in the diet to prevent a negative nitrogen balance is an essential amino acid. Essential amino acids cannot be synthesized by the human body and must therefore be obtained from dietary sources. From the list provided, Threonine (D) is the correct answer because it is an essential amino acid, meaning it is vital for maintaining nitrogen balance by being part of the protein intake necessary to match nitrogen output. Options A (Alanine), B (Arginine), C (Glycine), and E (Serine) are nonessential amino acids, meaning that they can be synthesized by the body, hence are not as critical to consume in the diet for the purpose of maintaining nitrogen balance.