Final answer:
A macromolecule is a large complex molecule made up of smaller organic molecules, forming structures essential for life like carbohydrates, lipids, proteins, and nucleic acids.
Step-by-step explanation:
A macromolecule is best described as a molecule composed of repeating units of smaller building blocks. Macromolecules are essential for life and are made up of smaller organic molecules that form large complex structures through polymerization. Examples of biological macromolecules include carbohydrates, lipids, proteins, and nucleic acids like DNA and RNA. Each class of macromolecules plays a crucial role in the structure and function of cells, making up the majority of a cell's dry mass. The unique properties of carbon allow these macromolecules to form complex structures critical for diverse biological processes.