Question

Which one is against the theory of ascent of sap given by Dixon and Jolly?

• A. Pores in tracheary elements
• B. Cohesion force of water molecules
• C. Adhesion force of water molecules
• D. Requirement of ATP

Answer 1

The correct option is D

Requirement of ATP

The theory of ascent of sap given by Dixon and Jolly is also called the 'Cohesion-tension theory'. According to this theory, loss of water from aerial parts of the plants creates a suction force in the xylem. This pulls up water from the roots. The water column rises rapidly because of the high surface tension of water. The water column does not break because of high cohesive forces between water molecules and adhesion between water and the tracheary elements. It is a passive process. It does not require ATP because it occurs along the concentration gradient of water.