A single macromolecule may contain many ______.

• A. several different functional groups
• B. different types of lipids
• C. monomer units
• D. isomers

Answer: (A)

A single macromolecule can host a variety of functional groups, giving it diverse chemical properties and reactive sites. Functional groups are specific atom clusters that largely determine how a molecule behaves—things like amino and carboxyl groups in proteins, phosphate groups in nucleic acids, and hydroxyl or carbonyl groups in carbohydrates. The presence of many different functional groups along a macromolecule enables a range of interactions, such as hydrogen bonding, ionic interactions, and catalytic activities, which in turn influence folding, binding, and reactivity.

While a macromolecule is often built from many monomer units, and some macromolecules include lipids or other components, the key idea here is the breadth of functional groups that can be present within a single molecule. Isomers refer to different arrangements of atoms that share the same formula, which isn’t a property describing what a single macromolecule “contains” in this sense, and saying a macromolecule contains many lipids doesn’t apply to the typical structure of most macromolecules.