Question

The ascent of xylem sap depends on _______.

• A. Cohesion of water molecules
• B. Adhesion of water molecules
• C. Transpiration pull
• D. Root pressure

Answer 1

Answer: (A), (B), (C)

Transpiration pull

Upward movement of water against gravity or ascent of sap in plants depends mainly on cohesion and adhesion of water molecules. Cohesive forces are the intermolecular attractive forces between water molecules and adhesive forces are the intermolecular attractive forces between water and other molecules, like the matrix. Transpiration pull is the suction pressure developed in the plant parts due to transpiration.