The opening and closing of the stomatal pore depends upon

Options

A. oxygen
B. temperature
C. water in guard cells
D. concentration of `CO_(2)` on stomata

Explanation

**Step-by-Step Solution:**

1. **Understanding Stomata**: Stomata are small openings found on the surfaces of leaves and stems of plants. They play a crucial role in gas exchange (oxygen and carbon dioxide) and transpiration (water loss).

2. **Role of Guard Cells**: Each stomatal pore is surrounded by a pair of specialized cells known as guard cells. These cells control the opening and closing of the stomata.

3. **Mechanism of Opening**: When water enters the guard cells, they become turgid (swollen and firm). This turgidity causes the guard cells to curve outward, leading to the opening of the stomatal pore.

4. **Mechanism of Closing**: Conversely, when water leaves the guard cells, they become flaccid (soft and limp). This flaccidity causes the guard cells to straighten, resulting in the closing of the stomatal pore.

5. **Factors Affecting Stomatal Movement**: The opening and closing of stomata depend primarily on the water content in the guard cells. Other factors like light, carbon dioxide concentration, and temperature can also influence stomatal behavior, but the direct mechanism is based on water movement.

6. **Conclusion**: Therefore, the opening and closing of the stomatal pore primarily depend on the water in the guard cells.

**Final Answer**: The opening and closing of the stomatal pore depends upon the water in guard cells.

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