Final answer:
Cohesive forces between water molecules are responsible for the pull on water, enabling processes like the rise of sap in trees and the surface tension that allows objects like paper clips to float on water.
Step-by-step explanation:
The process that exerts the pull on water molecules is known as cohesion. In the context of biology, this principle explains how sap can rise to the tops of tall trees through xylem vessels, a phenomenon driven by cohesive forces between water molecules.
Additionally, in the context of physics, surface tension is a related concept where the cohesive forces between liquid molecules cause the surface to contract and resist external force, as seen when a paper clip floats on the water's surface.