Question

Which of the following is not a function of proteins?
A) Formation of hair, wool, skin and nails.
B) As a biological catalyst in the form of enzymes.
C) As food in the form of meat, eggs.
D) As an energy provider for metabolism.

Answer 1

Hint: Of the given options, one option represents the function of a carbohydrate. Identify this function. The remaining three functions are of proteins.

Complete answer:
Hairs, nails, wool and skin contain proteins. Thus, one of the functions of proteins is the formation of hairs, nails, wool and skin for the human body and animal body.
Some foods are rich in protein. These include eggs, fish and meat. Thus, another important function of proteins is to be a part of food. Enzymes are important biological catalysts. They catalyze several functions in our body. Enzymes are made up of amino acids. Thus, enzymes are proteins. Thus, another function of proteins is to serve as a biological catalyst.
However, proteins do not provide energy for metabolism. Glucose provides the energy for metabolism. Glucose is not an enzyme. Glucose is a carbohydrate, a monosaccharide. Glucose does not contain amino acids whereas proteins contain amino acids.
Thus, the energy provider is not a function of proteins.

Hence, the correct option is the option (D) As energy provider for metabolism.

Note: Proteins are polypeptides made from several amino acids. Protein contains peptide linkages. A peptide linkage is the amide bond. A peptide linkage is formed when an amino group of one amino acid condenses with a carboxylic group of another amino acid. This forms an amide bond and a water molecule.