Question

Which is released during the formation of a peptide bond?
(A) Five-carbon sugar
(B) An amino group
(C) An amino acid
(D) A water molecule

Answer 1

Carboxylic acids are compounds consisting of an acid group which is $- COOH$ group. Amines are compounds consisting of a basic group which is $- N{H_2}$ group. These two groups combine with each other leads to the formation of a peptide bond undergoing the dehydration reaction.

Complete answer:
Chemical compounds are classified into functional groups based on the groups present in them. Some of the well-known and important functional groups are carboxylic acids and amine groups.
Carboxylic acids are acidic compounds consisting of the $-$ COOH group. These compounds can easily release a hydrogen ion, considered acidic compounds. Formic acid and acetic acid are examples of carboxylic acids.
Amines are the basic compounds consisting of the $- N{H_2}$ group. As these compounds consist of a nitrogen atom with a lone pair of electrons on it readily available to donate them, these are considered basic compounds.
When carboxylic acid and amine compounds are combined it leads to the formation of a peptide bond with the general formula of $- CONH$ , this bond is possible when $- COOH$ group and $- N{H_2}$ group loses water molecules.
Thus, during the formation of a peptide bond, a water molecule can be released.
Option D is the correct one.

Note:
The peptide bond is generally seen in amino acids. The name of amino acids itself indicates the presence of amine and acid. As the peptide bond was formed from amine and carboxylic acid groups. amino acids are the building blocks of proteins. Thus, a peptide bond is important in the life of organisms.