Question

Which of the following force act between the water column and walls of xylem?

• A. Adhesive force
• B. Cohesive force
• C. Gravitational force
• D. None of the above

Answer 1

Answer: (A)

Adhesive force

Transpiration pull theory was put forward by Dixon and Joly. According to this theory, the ascent of sap in plants is a physical process, the lifting force for which is provided by the pulling force generated by transpiration. The cohesion forces between the water molecules help in maintaining a continuous water column and the adhesion forces between water molecules and the tracheary elements help in sticking to water to the xylary elements.

Thus, the correct answer is option A.