Question

which of the following structures represents a lipid?

Explanation:

Lipids are composed of fatty - acid chains or related molecules. The first structure is a nucleotide (sugar - phosphate - nitrogenous base), the second is an amino - acid (amine, carboxyl, and R - group), the third is a triglyceride (glycerol backbone with fatty - acid chains, characteristic of lipids), and the fourth is a carbohydrate (multiple hydroxyl groups and a carbonyl group).

Answer:

The third structure represents a lipid.