Which statements are correct about guard cells?
I.They are modified group tissues
II.They are chlorophyllous
III.Its outer wall is thin and inner wall is highly thickened
IV.They regulates stomatal movement for transpiration and gaseous exchange

Options

A. All except I
B. all except II
C. all except III
D. all except Iv

Answer

To determine which statements about guard cells are correct, let's analyze each statement step by step:

1. **Statement I: They are modified group tissues.**
- This statement is incorrect. Guard cells are not classified as modified group tissues; rather, they are specialized cells that are part of the epidermis of the leaf. The cells surrounding guard cells are known as subsidiary cells, which are modified.

2. **Statement II: They are chlorophyllous.**
- This statement is correct. Guard cells contain chloroplasts, which means they are capable of photosynthesis. This is why they are referred to as chlorophyllous.

3. **Statement III: Its outer wall is thin and inner wall is highly thickened.**
- This statement is also correct. The outer wall of guard cells is indeed thinner compared to the inner wall, which is thickened. This structural difference is crucial for their function in regulating the opening and closing of stomata.

4. **Statement IV: They regulate stomatal movement for transpiration and gaseous exchange.**
- This statement is correct as well. The primary function of guard cells is to control the opening and closing of stomata, which facilitates transpiration (water loss) and gaseous exchange (such as oxygen and carbon dioxide) in plants.

**Conclusion:**
- The correct statements about guard cells are II, III, and IV. Only statement I is incorrect.

### Summary of Correct Statements:
- II. They are chlorophyllous.
- III. Its outer wall is thin and inner wall is highly thickened.
- IV. They regulate stomatal movement for transpiration and gaseous exchange.