Mass flow of water occurs due to the

Options

A. Adhesive properties of water
B. Cohesive properties of water
C. Adhesive and cohesive properties of water
D. None of above

Answer

**Step-by-Step Solution:**

1. **Understanding Mass Flow of Water**: The mass flow of water in plants primarily occurs through the xylem, which is responsible for transporting water from the roots to the leaves.

2. **Identifying Key Properties of Water**: The movement of water is influenced by two main properties of water: cohesion and adhesion.

3. **Cohesion**: This is the mutual attraction between water molecules. Cohesive forces allow water molecules to stick to each other, which is crucial for maintaining a continuous column of water in the xylem vessels.

4. **Adhesion**: This refers to the attraction between water molecules and other polar surfaces, such as the walls of the xylem vessels. This property helps water to cling to the xylem walls, facilitating its upward movement.

5. **Role of Transpiration**: The process of transpiration (the evaporation of water from plant leaves) creates a negative pressure (transpiration pull) in the xylem, which helps to draw water upward. This is where both cohesion and adhesion play a critical role.

6. **Surface Tension**: The cohesive forces between water molecules also contribute to surface tension, which is the tendency of water to minimize its surface area. This property further aids in the upward movement of water through capillary action.

7. **Conclusion**: Therefore, the mass flow of water occurs due to both the adhesive and cohesive properties of water, making the correct answer to the question "adhesive and cohesive properties of water."

**Final Answer**: The mass flow of water occurs due to the adhesive and cohesive properties of water.

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