Which term describes the force of attraction between water molecules and a surface, such as xylem walls?

Which term describes the force of attraction between water molecules and a surface, such as xylem walls?

• A. Adhesion
• B. Cohesion
• C. Osmosis
• D. Surface tension

Answer: (A)

Adhesion is the term for the attraction between water and a surface. Water is polar and can form hydrogen bonds with the molecules on the xylem walls (cellulose and other hydrophilic components), so it tends to cling to the surface. This sticking to the walls helps water rise through narrow tubes in plants by capillary action, especially when it works together with cohesion, the attraction between water molecules themselves, to create a continuous column. Cohesion describes water–water attraction, not water–surface attraction. Osmosis is the movement of water across a semipermeable membrane driven by solute differences. Surface tension is the cohesive force at the air–water interface that gives the surface its “skin,” not specifically the interaction with a surface like xylem walls.

Adhesion is the term for the attraction between water and a surface. Water is polar and can form hydrogen bonds with the molecules on the xylem walls (cellulose and other hydrophilic components), so it tends to cling to the surface. This sticking to the walls helps water rise through narrow tubes in plants by capillary action, especially when it works together with cohesion, the attraction between water molecules themselves, to create a continuous column.

Cohesion describes water–water attraction, not water–surface attraction. Osmosis is the movement of water across a semipermeable membrane driven by solute differences. Surface tension is the cohesive force at the air–water interface that gives the surface its “skin,” not specifically the interaction with a surface like xylem walls.