Question

All of the following enhance water transport in terrestrial plants except

• A. hydrogen bonds linking water molecules
  
• B. capillary action due to adhesion of water molecules to the walls of xylem
  
• C. evaporation of water from the leaves
  
• D. K+ being transported out of the guard cells

Answer 1

The correct option is D K+ being transported out of the guard cells

Ascent of sap in plants is driven by the process of transpiration. Transpiration creates a pull that causes the upward movement of water in the plant. Various physical properties of water such as cohesion, adhesion and surface tension also play a major role in the ascent of sap in plants.

When K+ions (solute) leave the guard cells, the water potential of guard cells increases and water moves out of the guard cells making them flaccid. This causes the stomata to close and, hence, transpiration stops. Subsequently, the water transport is also stopped.