Which of the following is not a major factor in the movement of xylem sap up in a tall tree?

Options

A. Plasmodesmata
B. Cohesion and adhesion
C. tension
D. transpiration

Answer

To determine which of the following is not a major factor in the movement of xylem sap up in a tall tree, we need to analyze each option provided:

1. **Plasmodesmata**: These are microscopic channels that connect plant cells, allowing for the transport of substances between them. However, they are not involved in the movement of xylem sap, which occurs through the xylem vessels (tracheids and vessel elements) that are dead cells. Therefore, plasmodesmata do not play a role in the upward movement of xylem sap.

2. **Cohesion and adhesion**: These are important properties of water. Cohesion refers to the attraction between water molecules, while adhesion refers to the attraction between water molecules and the walls of the xylem vessels. Both of these properties are crucial for the movement of water through the xylem, as they help maintain the continuous column of water that is pulled up from the roots to the leaves.

3. **Tension**: This is created by the process of transpiration, where water evaporates from the leaves, creating a negative pressure that pulls water upward through the xylem. Tension is a significant factor in the movement of xylem sap.

4. **Transpiration pull**: This is directly related to tension and refers to the negative pressure created by the loss of water from the leaves. It is a major driving force for the upward movement of water in tall trees.

Based on this analysis, the option that is not a major factor in the movement of xylem sap is:

**Answer: Plasmodesmata (Option 1)**