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

Options

A. weak gravitational pull
B. transpiration pull
C. lignified thick walls
D. cohesion and adhesion

Answer

To solve the question about why rupture and fractionation do not usually occur in the water column in vessels/tracheids during the ascent of sap, we can break down the reasoning into the following steps:

### Step-by-Step Solution:

1. **Understanding Ascent of Sap**:
- The ascent of sap refers to the movement of water and nutrients from the roots of the plant to its aerial parts (leaves and stems). This process is vital for plant health and growth.

2. **Key Processes Involved**:
- Several processes contribute to the ascent of sap:
- **Osmosis**: Water is absorbed by the roots from the soil.
- **Capillary Action**: Water rises through narrow spaces in the xylem due to surface tension.
- **Root Pressure**: Pressure generated in the roots helps push water upward.
- **Cohesion and Adhesion**: These forces help maintain the integrity of the water column in the xylem.
- **Transpiration**: Loss of water from leaves creates a negative pressure that pulls water upward.

3. **Role of Cohesion and Adhesion**:
- **Cohesion**: This is the force of attraction between water molecules. It helps to keep the water molecules together, forming a continuous column in the xylem.
- **Adhesion**: This is the force of attraction between water molecules and the walls of the xylem vessels. It helps water to cling to the xylem walls, preventing the column from breaking.

4. **Preventing Rupture and Fractionation**:
- The combination of cohesion and adhesion ensures that the water column remains stable and does not break (rupture) or separate into smaller parts (fractionation) as it moves upward through the xylem vessels.

5. **Conclusion**:
- Therefore, the reason that rupture and fractionation do not usually occur in the water column during the ascent of sap is primarily due to the cohesive and adhesive properties of water.

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