Which of the following statement is true for stomatal apparatus

Options

A. Inner walls of guard cell are thick
B. Guard cells possess no chloroplasts and mitochondria
C. Guard cells are not always surrounded by subsidiary cells
D. Stomata are involved in gasesous exchange and not transpiration

Answer

### Step-by-Step Solution:

1. **Understanding the Stomatal Apparatus**: The stomatal apparatus consists of three main components: guard cells, stomatal pore, and subsidiary cells.

2. **Identifying Guard Cells**: Guard cells are specialized cells that regulate the opening and closing of the stomatal pore. They are typically kidney-shaped in dicots and dumbbell-shaped in monocots.

3. **Structure of Guard Cells**: The inner walls of guard cells are thick and inelastic, while the outer walls are thinner. This structure is essential for their function in regulating gas exchange.

4. **Presence of Chloroplasts**: Guard cells contain chloroplasts, which allow them to perform photosynthesis, contrary to the claim that they do not possess chloroplasts or mitochondria.

5. **Role of Subsidiary Cells**: Guard cells are always surrounded by subsidiary cells, which are modified epidermal cells that support the function of guard cells.

6. **Function of Stomata**: Stomata are involved in both gaseous exchange (such as oxygen and carbon dioxide) and transpiration (the loss of water vapor), not just gas exchange alone.

7. **Evaluating the Statements**:
- The first statement about the inner walls of guard cells being thick is true.
- The second statement about guard cells lacking chloroplasts and mitochondria is false.
- The third statement about guard cells not being surrounded by subsidiary cells is false.
- The fourth statement about stomata being involved only in gaseous exchange is also false.

8. **Conclusion**: The only true statement regarding the stomatal apparatus is that the inner walls of the guard cells are thick.

### Final Answer:
The true statement for the stomatal apparatus is: **The inner walls of the guard cells are thick.**

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