Which of the following is not a macromolecule?

a. Lipid

b. Protein

c. Carbohydrate

d. Platelet

The correct answer is a - Lipid

Lipids are not considered as macromolecules because unlike proteins, carbohydrates and nucleic acids which polymers, lipids are composed of a single unit made up a glycerol backbone to which two or three fatty acids are linked.

Lipids are not polymers made up of individual subunits called monomers. They contain only one molecule and are not macromolecuels.

Examples of lipids include waxes, steroids, phospholipids and detergents. Lipids are generally hydrophobic and insoluble in water.