What are polymers?

• A. Monomers that are loosely connected
• B. Small molecules joined to form simple molecules
• C. Made up of many molecules all strung together to form really long chains
• D. Simple sugars

Answer: (C)

Polymers are large molecules built by linking many repeating units called monomers into long chains. That continuous chain of monomers creates a big, single macromolecule, which is the essence of what a polymer is. This idea is captured by the description of being made up of many molecules all strung together to form really long chains.

Think of examples: DNA is a polymer made from nucleotide monomers; proteins are polymers of amino acids; starch is a polymer of glucose units; plastics like polyethylene are polymers of ethylene. Simple sugars, on the other hand, are often the monomers that join to form polymers, not the polymers themselves. The first option implies only loose connections, which doesn’t reflect the covalent bonds that hold polymer chains together, and the second option describes assembling small molecules into basic units rather than forming long chains.