Which is not associated with ascent of sap in tall trees

Options

A. Continuity of water column
B. Cohesion and adhesion of water moleciules
C. Transpiration pull
D. Pressure of tracheary elememts

Answer

To determine which phenomenon is not associated with the ascent of sap in tall trees, we will analyze each of the given options.

### Step-by-Step Solution:

1. **Understanding the Ascent of Sap**:
- The ascent of sap refers to the upward movement of water and dissolved minerals from the roots to the upper parts of the plant, primarily through the xylem tissue.

2. **Analyzing Each Option**:
- **Option 1: Continuity of the Water Column**:
- This is essential for the ascent of sap. A continuous column of water is necessary to facilitate the upward movement against gravity.

- **Option 2: Cohesion and Adhesion of Water Molecules**:
- Cohesion (the attraction between water molecules) and adhesion (the attraction between water molecules and the walls of xylem vessels) are crucial for maintaining the water column and assisting in its upward movement.

- **Option 3: Transpiration Pull**:
- Transpiration creates a negative pressure in the leaves, pulling water upward through the xylem. This is a vital mechanism for the ascent of sap.

- **Option 4: Pressure of the Tracheary Elements**:
- While tracheary elements (like tracheids and vessel elements) do conduct water, the pressure they exert is not a primary factor in the ascent of sap. The ascent is mainly driven by root pressure, cohesion, adhesion, and transpiration pull.

3. **Conclusion**:
- After analyzing all options, the phenomenon that is **not associated** with the ascent of sap in tall trees is **Option 4: Pressure of the Tracheary Elements**.

### Final Answer:
**The correct option is: Pressure of the Tracheary Elements.**

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