Question

The force with which water molecules are held together in xylem is

• A. Imbibition pressure
• B. Osmotic pressure
• C. Adhesion force
• D. Cohesion force

Answer 1

The correct option is D Cohesion force

The force with which water molecules are held together in xylem is cohesion force. The rate of transpiration is high during the day time. The water is lost from guard cell which leads to decrease in the water potential of guard cell as compared to the surrounding cell. To stabilize the water potential in the guard cell water rushes from the neighboring cell which creates a cohesion pull in the xylem vessels to pull the water up to the guard cell. The force with which water molecules are held together in xylem is cohesion force which exist between water molecules and bond them together.

So, the correct answer is option C.