What are monomers?

• A. Long molecules formed by many repeating units
• B. Small molecules which may be joined together in a repeating fashion to form more complex molecules called polymers
• C. Proteins formed from amino acids
• D. Nucleotides forming DNA

Answer: (B)

Monomers are small molecules that can be linked together in a repeating fashion to form larger molecules called polymers. This building-block idea means that many monomer units join to create a polymer chain. For example, amino acids are monomers that can join to form proteins, and nucleotides are monomers that assemble into DNA. The statement describing monomers this way captures the concept precisely. The other descriptions refer to the polymers themselves or to specific macromolecules rather than the small units that build them.