Question

Write a paragraph explaining how adhesion, cohesion, and capillary action all enable water to go from the roots to the top of a tall tree.

Answer 1

Water is pulled from the roots to the top of a tall tree by a combination of adhesion, cohesion, and capillary action working with transpiration. Water molecules stick to each other through cohesion (hydrogen bonds), forming an unbroken column in the xylem, and they stick to the cellulose walls of the xylem by adhesion, which helps the column cling to the conduits instead of breaking under gravity. Evaporation of water from leaf stomata (transpiration) creates a negative pressure (tension) that pulls on this cohesive column, and capillary action in the very narrow xylem vessels helps initiate and assist the upward movement by drawing water along the walls. Together, these forces maintain a continuous, tension-bearing stream so water taken up by the roots can be transported all the way to the treetop.