Question

Water moves up against gravity and even for a tree of 20m height, the tip receives water within two hours. The most important physiological phenomenon which is responsible for the upward movement of water is

Answer 1

Transpiration:


The loss of water as water vapour from the aerial parts of the leaves is called transpiration.


Transpiration pull:


Transpiration causes a negative pressure in the xylem vessels resulting in a suction force called transpirational pull. This force is exerted on the water molecules in the xylem vessels.


Final answer: Transpiration pull.