Question

Cohesion force existing amongst water molecules contributes to
A) Plasmolysis
B) Ascent of sap
C) Osmosis
D) Translocation

Answer 1

Hint: Cohesive force is the strong force of attraction which exists between the similar molecules. Cohesive force in water is due to the hydrogen bond which exists between the water molecules and holds it together.

Complete Answer:
- Force of cohesion holds similar molecules together. In water molecules, a strong cohesive force exists due to the presence of hydrogen bonds between the molecules. The hydrogen bond in water exists between the hydrogen and oxygen of another water molecule. In plants this cohesive force of water is used in the ascent of sap.
- Ascent of sap is the upward movement of water and minerals from root to the apex. The cohesive force in water molecules helps in upward movement of water against the gravity.
- Plasmolysis is the process of movement of water out of the cell when placed in a hypertonic solution.
- Osmosis is the process of movement of water molecules from regions of higher concentration to lower concentration through a semipermeable membrane.
- Translocation is the movement of sucrose and other substances around a plant is called translocation.

The correct answer is (B). Cohesion force existing amongst water molecules contributes to the ascent of sap.

Note: Transpiration pull, cohesion property of water and hydration of the cell walls are responsible for the ascent of sap. It takes place in the xylem.