The rupture and fractionation do not usualy occur in the water column in vessel/tracheids during the ascent of sap because of

Options

A. Transpiration pull
B. Lignified thick walls
C. Cohension and adhesion
D. Weak gravitational pull

Answer

### Step-by-Step Solution:

1. **Understanding Ascent of Sap**: The ascent of sap refers to the process by which water and dissolved minerals move from the roots of a plant to its leaves and other parts. This movement is crucial for plant health and functioning.

2. **Identifying Key Forces**: The ascent of sap is primarily driven by two key forces:
- **Cohesive Force**: This is the attraction between water molecules themselves. Water molecules tend to stick together due to hydrogen bonding, which helps maintain a continuous column of water in the xylem vessels.
- **Adhesive Force**: This is the attraction between water molecules and the walls of the xylem vessels. Water molecules adhere to the xylem walls, which helps counteract the effects of gravity.

3. **Role of Transpiration**: Transpiration, the process of water evaporation from the leaves, creates a negative pressure (tension) in the xylem. This tension pulls the water column upward.

4. **Preventing Rupture and Fractionation**: The cohesive and adhesive forces work together to prevent the rupture and fractionation (breaking apart) of the water column in the xylem vessels. The strong cohesive forces keep the water molecules together, while the adhesive forces help them stay attached to the xylem walls. This combination allows the water column to withstand the tension created by transpiration without breaking.

5. **Conclusion**: Therefore, the rupture and fractionation do not usually occur in the water column in vessels/tracheids during the ascent of sap because of the cohesive and adhesive forces acting on the water molecules.

### Final Answer:
The rupture and fractionation do not usually occur in the water column in vessel/tracheids during the ascent of sap because of **cohesion and adhesion**.

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