Answer:
A nucleic acid monomer is a 5-carbon cyclic ring that has a phosphate molecule covalently bonded to the 5’ carbon and a nitrogenous base bonded to its 1’ carbon.
A protein monomer is an amino acid. An amino acid is composed of an alpha carbon bonded to a carbonyl group (COOH), amino groups (NH₂) and a variable side chains that varies among the types of amino acids.
(See the attached illustrations)
