Which of the following compounds does NOT consist of polymers?

Lipids are unique among the options provided because they do not consist of polymers. Polymers are large molecules made up of repeating subunits, called monomers. Proteins are polymers made of amino acids linked by peptide bonds, nucleic acids are polymers made of nucleotides, and carbohydrates consist of sugar molecules that can form long chains (polysaccharides).

In contrast, lipids are a diverse group of hydrophobic molecules that include fats, oils, and steroids. They are primarily composed of glycerol and fatty acids, but they do not form long chains of repeating monomers to the extent observed in the other biomolecules. While lipids can aggregate into larger structures such as cell membranes, they are not structured as traditional polymers and do not have the repeating unit characteristic of true polymers. This fundamental difference allows lipids to perform distinct biological functions that are not reliant on a polymeric structure.