When stem of a herbaceous plant is cut, water or sap oozes out, this is due to

Options

A. Guttation
B. Transpiration pull
C. Root pressure
D. Imbibition

Answer

**Step-by-Step Solution:**

1. **Understanding the Context**: When the stem of a herbaceous plant is cut, it is observed that water or sap oozes out from the cut surface. This phenomenon can be explained by various physiological processes in plants.

2. **Identifying the Options**: The options provided are:
- Guttation
- Transpiration pull
- Root pressure
- Imbibition

3. **Analyzing Guttation**: Guttation is the process where water is expelled from the plant in liquid form, usually through specialized structures called hydathodes. However, this typically occurs under specific conditions (like high humidity) and is not the primary reason for sap oozing out when a stem is cut.

4. **Analyzing Transpiration Pull**: Transpiration pull refers to the process where water is drawn up from the roots to the leaves due to the evaporation of water from the leaf surfaces. While this is crucial for water movement in plants, it does not directly cause sap to ooze out when a stem is cut.

5. **Analyzing Root Pressure**: Root pressure is generated when water and nutrients are actively absorbed from the soil into the roots. This creates a positive pressure in the xylem vessels, which can push water upwards. When the stem is cut, this pressure can cause water or sap to ooze out from the cut surface.

6. **Analyzing Imbibition**: Imbibition is the process of water absorption by solids, such as seeds or dry wood, causing them to swell. This process does not explain the oozing of sap from a cut stem.

7. **Conclusion**: The correct explanation for the oozing of sap when the stem of a herbaceous plant is cut is due to **root pressure**. This positive pressure in the xylem forces the sap out of the cut surface.

**Final Answer**: The sap oozes out due to **root pressure**.

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