Monomers are the functional molecules forming the polymers when an random amount of units (monomers) are linked form an assembly (polymer).
This could be exposed by considering the glucose as the monomer forming the glycogen which is a polymer that serves as a form of energy storage in animals, fungi, and bacteria; it is constituted by about 30,000 units of both lineal and branched glucose which provide many features that the glucose doesn't have by itself.
