Final answer:
Lipids are the class of biological macromolecules that are generally not water soluble. They are composed of hydrophobic or nonpolar molecules, which distinguishes them from the other macromolecules like carbohydrates, proteins, and nucleic acids that often have polar regions allowing them to dissolve in water.
Step-by-step explanation:
Among the four major classes of biological macromolecules, which include carbohydrates, proteins, nucleic acids, and lipids, it is the lipids that are generally not water soluble. Lipids are hydrophobic or nonpolar molecules, mostly made up of hydrocarbons, which do not interact favorably with water.
On the other hand, carbohydrates, proteins, and nucleic acids often contain polar groups that allow them to be more soluble in water. These macromolecules are synthesized through a process called dehydration synthesis, during which monomers combine to form polymers while releasing water molecules.
This reaction highlights how life's complex structures are built from simpler units, underscoring the remarkable efficiency and diversity of biological molecules.