According to Dixon and Jolly's Cohesion Theory the channel for ascent of sap is

Options

A. xylem parenchyma
B. lumen of vessels and tracheids of xylem
C. xylem fibre
D. cortical cells

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the channel for the ascent of sap according to Dixon and Jolly's Cohesion Theory.

2. **Cohesion Theory Overview**: According to Dixon and Jolly's Cohesion Theory, there is a continuous column of water that moves from the roots through the stem and into the leaves of the plant.

3. **Role of Xylem**: The ascent of sap occurs through the tracheary elements of the xylem. These elements are responsible for the transport of water and minerals.

4. **Types of Tracheary Elements**: The two main types of tracheary elements in the xylem are tracheids and vessel elements. Both play a crucial role in forming a continuous water column.

5. **Continuous Water Column**: The water column is maintained continuously due to the presence of numerous tracheary elements. Even if one or a few of them are blocked, the continuity of the water column is not disrupted.

6. **Forces Involved**: The upward movement of water against gravity is facilitated by transpiration, which creates a pull. Additionally, cohesion (attraction between water molecules), adhesion (attraction between water molecules and the walls of the tracheary elements), and surface tension contribute to maintaining the water column.

7. **Conclusion**: Based on the explanation, the correct answer to the question is that the channel for the ascent of sap is through the tracheary elements of the xylem.

**Final Answer**: The channel for the ascent of sap according to Dixon and Jolly's Cohesion Theory is through the tracheary elements of the xylem.

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