Final answer:
The cohesion and adhesion of water molecules help overcome gravitational pull.
Step-by-step explanation:
The cohesion and adhesion of water molecules help overcome gravitational pull when water travels upward from roots to leaves.
Water molecules have a strong attraction to each other through cohesion, which allows water to move in a continuous column through the xylem vessels. Adhesion refers to the attraction of water molecules to the walls of the xylem vessels. This combination of cohesion and adhesion enables water to move upwards against gravity.
There is no blocking of water molecules by the Casparian strip, as it is involved in regulating the entry of substances into the xylem. The upward movement of water is not primarily due to upward pressure from the roots, but rather the cohesive and adhesive properties of water.
Learn more about Movement of water in plants