Question

Which of the following force accounts for the ascent of sap?

• A. Adhesive force
• B. Cohesive force
• C. Transpirational pull
• D. All of the above

Answer 1

Answer: (D)

All of the above

The ascent of sap is the mechanism by which water moves from the roots to the top of the trees. Studies on the process of an ascent of sap show that the strong cohesive force between the water molecules (cohesion), the attraction between water molecules and the wall of the xylem elements (adhesion) and the transpiration pull creates a tension on the water column, which ensures continuity of water column in plants. The water lost from the leaves during transpiration creates a high solute potential and reduces water potential. The reduced water potential creates a suction pull and allows ascent of sap.

Thus, the correct answer is option D.