Osmotic pressure in the leaf cells is

Options

A. excessive transpiration
B. low transpiration
C. excessive absorption
D. guttation

Explanation

**Step-by-Step Solution:**

1. **Understanding Osmotic Pressure**:
- Osmotic pressure (OP) is the pressure required to prevent the flow of water across a semi-permeable membrane due to osmosis. It is influenced by the concentration of solutes in the solution.

2. **Role of Leaf Cells**:
- Leaf cells are crucial for the process of transpiration, where water is evaporated from the leaf surface into the atmosphere. This process helps in the movement of water and nutrients from the roots to the leaves.

3. **Transpiration Process**:
- During transpiration, water vapor exits the leaf cells, leading to a decrease in water content within the cells. This loss of water causes the osmotic pressure within the leaf cells to increase.

4. **Exosmosis**:
- As water moves out of the leaf cells (exosmosis), the osmotic pressure rises. This is because the concentration of solutes in the remaining water increases, leading to a higher osmotic pressure.

5. **Effect of Transpiration on Turgor Pressure**:
- When water leaves the cells, the turgor pressure (the pressure of the cell contents against the cell wall) decreases, causing the cells to become flaccid. Conversely, if water enters the cells, the turgor pressure increases, making the cells turgid.

6. **Evaluating the Options**:
- **Excessive Transpiration**: This leads to a high osmotic pressure due to the loss of water from the leaf cells.
- **Low Transpiration**: Would retain water in the cells, leading to lower osmotic pressure.
- **Excessive Absorption**: Would cause cells to become turgid, decreasing osmotic pressure.
- **Guttation**: A different process involving the exudation of xylem sap, not directly related to osmotic pressure in leaf cells.

7. **Conclusion**:
- The correct answer is that the osmotic pressure in leaf cells is due to excessive transpiration.

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