How do transpiration cohesion and adhesion all work together

How do transpiration, cohesion and adhesion all work together to provide the forces necessary to overcome gravity to transport water from the roots to the leaves without expending energy? Include definitions of the three terms as they relate to the transport of water up the plant.

HINT: Begin with transpiration (define); then explain how cohesion (define) and adhesion (define) work together to get water up the plant. Don\'t be too long

Solution

Transpiration is the process of water movement through a plant and evaporates from aerial parts - leaves, stems and flowers. Water is necessary for plants but only a small amount of water is used for growth and metabolism, above 97% of water is lost by transpiration and guttation. Transpiration occurs through the stomata cells during photosynthesis. Transpiration also cools plants, changes osmotic pressure of cells, and enables mass flow of mineral nutrients and water from roots to shoots.

Cohesion: It is the phenomenon attraction between the similar molecules. The water molecules remain attracted by cohesive forces and cannot be separated from one another.

Adhesion: The ability of a substance to stick to an unlike molecules (attraction between unlike molecules)

Cohesion Tension theory is a theory of ascent of sap. It was proposed by Dixon and Joly in 1894. The theory describes the movement of water from roots to the leaves of a plant. Water molecules are bonded to each other by hydrogen bonding, hence water form a string (linear) of molecules during its movement toward xylem.

The water is filled inside the xylem capillaries and due to the cohesion and adhesion properties of water it forms a continuous water column from roots to leaves.

Cohesive and adhesive properties of water molecules to form an unbroken continuous water column in the xylem. Transpiration pull exerted on this water column. The water column could not be pulled away from the xylem walls because of cohesion-adhesion properties of water.