As a tree begins transpiring in the morning, tension pressure occurs first in

Options

A. Leaf
B. Branches
C. Root
D. All the regions of the tree

Answer

### Step-by-Step Solution:

1. **Understanding Transpiration**: Transpiration is the process by which water vapor is released from the leaves of a plant into the atmosphere. This process primarily occurs during the day when the stomata (tiny openings on leaves) are open for gas exchange.

2. **Initiation of Tension Pressure**: As transpiration begins, water evaporates from the leaf surface. This loss of water creates a negative pressure (tension) within the leaf.

3. **Development of the Transpiration Pool**: The negative pressure created in the leaf due to water loss leads to the formation of what is known as the "Transpiration Pool." This pool is responsible for pulling water upward from the roots through the xylem vessels.

4. **Sequence of Tension Pressure**: The tension pressure does not occur simultaneously throughout the plant. It starts first in the leaves, then moves to the branches, followed by the roots, and finally affects the entire tree.

5. **Conclusion**: Therefore, the first location where tension pressure occurs as a tree begins transpiring in the morning is in the leaves.

### Final Answer:
Tension pressure occurs first in the **leaf**.

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