Which is NOT an element found in keratin?

Which is NOT an element found in keratin?

• A. Sulfur
• B. Oxygen
• C. Monomer
• D. Hydrogen

Answer: (C)

Keratin is a protein built from amino acids, so its composition includes elements like hydrogen, oxygen, and sulfur (as well as nitrogen and carbon). Sulfur in cysteine residues forms disulfide bonds that give keratin its strength, while hydrogen and oxygen are part of the peptide bonds and side chains. A monomer is a building-block unit of a polymer, not an element. Keratin is composed of amino acid monomers, so “monomer” describes a unit, not an elemental substance. Because the question asks for an element found in keratin, monomer is the term that does not fit.

Keratin is a protein built from amino acids, so its composition includes elements like hydrogen, oxygen, and sulfur (as well as nitrogen and carbon). Sulfur in cysteine residues forms disulfide bonds that give keratin its strength, while hydrogen and oxygen are part of the peptide bonds and side chains. A monomer is a building-block unit of a polymer, not an element. Keratin is composed of amino acid monomers, so “monomer” describes a unit, not an elemental substance. Because the question asks for an element found in keratin, monomer is the term that does not fit.