Stomatal aperture is surrounded by guard cells and widens (opens) when guard cells are

Options

A. Flaccid
B. Turgid
C. Bean shaped
D. Dumb-bell shaped .

Answer

**Step-by-Step Solution:**

1. **Understanding Stomatal Structure**: Stomata are small openings on the surface of leaves, surrounded by specialized cells known as guard cells. These guard cells play a crucial role in regulating the opening and closing of the stomatal aperture.

2. **Function of Guard Cells**: The primary function of guard cells is to control the rate of transpiration (water loss) and gas exchange (like CO2 and O2) in plants. The shape and turgidity of guard cells determine whether the stomatal aperture is open or closed.

3. **Turgidity of Guard Cells**: When guard cells become turgid (swollen with water), they change shape. This turgidity is often caused by the accumulation of potassium ions (K+) within the guard cells, which leads to water entering the cells via osmosis.

4. **Mechanism of Opening Stomata**: As potassium ions accumulate in the guard cells, water follows by osmosis, causing the guard cells to swell. This swelling causes the guard cells to bend away from each other, resulting in the widening (opening) of the stomatal aperture.

5. **Conclusion**: Therefore, the stomatal aperture widens (opens) when guard cells are turgid. The correct answer to the question is option B: Turgid.

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