Ah, I'm not sure. I hope someone helps you!
Answer:
Cohesion is an attractive force between same kind of molecules while adhesive force exists between different kinds of molecules. When water moves inside vascular tissue they contain cell sap. It is these two forces which keep materials in cells and water can easily move them to different parts where they are necessary.
The 4 classes of biological macromolecules are carbohydrates, lipids, proteins and nucleic acids.
