Which theory explains how water is pulled upward from the roots due to the cohesion of water molecules?

The transpiration-cohesion theory explains the process through which water is transported upward from the roots of a plant to its leaves. This phenomenon is primarily driven by the cohesion of water molecules, which are attracted to one another due to hydrogen bonding. As water evaporates from the stomata on the surface of leaves, it creates a negative pressure in the leaf's air spaces. This negative pressure pulls water upward from the roots through the xylem vessels.

In addition to cohesion, adhesion (the attraction between water molecules and the walls of the xylem vessels) also contributes to the upward movement of water, but cohesion is the key force that allows this process to occur effectively. The transpiration-cohesion theory seamlessly integrates these concepts to explain how the continuous column of water can be maintained from roots to leaves, enabling plants to obtain the necessary water for photosynthesis and other physiological processes.

The other theories and models, such as the pressure-flow model, focus on different aspects of plant transport systems and do not specifically address the cohesion of water molecules as the primary driving force for water movement in this context.