Ascent of sap in herbs is due to

Options

A. Root pressure
B. Transpiratory pull
C. Cohesion of water
D. Adhesion of water

Answer

**Step-by-Step Solution:**

1. **Understanding the Ascent of Sap**: The ascent of sap refers to the movement of water and nutrients from the roots of the plant to its leaves and other parts. This process is crucial for the plant's growth and functioning.

2. **Identifying the Role of Roots**: The roots, particularly the root hairs, play a significant role in absorbing water and minerals from the soil. When these root hairs absorb water, they create pressure within the roots.

3. **Defining Root Pressure**: The pressure created by the absorbed water in the roots is known as root pressure. This pressure helps in pushing the sap (water and dissolved minerals) upward through the plant, but it is effective only for short distances, typically in smaller plants or herbs.

4. **Evaluating Other Options**:
- **Transpiratory Pull**: This mechanism involves the loss of water from the leaves through transpiration, which creates a negative pressure that pulls water upward. However, this is more effective in taller plants rather than herbs.
- **Cohesion of Water**: This refers to the attraction between water molecules, which helps maintain a continuous column of water in the xylem. While important, it does not solely account for the ascent of sap in herbs.
- **Adhesion of Water**: This is the attraction of water molecules to the surfaces of the xylem vessels. Like cohesion, it contributes to the movement of water but is not the primary reason for the ascent of sap in herbs.

5. **Conclusion**: Based on the above analysis, the ascent of sap in herbs is primarily due to root pressure.

**Final Answer**: The ascent of sap in herbs is due to **a. root pressure**.

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