Which of the following is incorrect ?

Options

A. Cuticle is present on the eipdermis of both stems and roots .
B. The outer walls of guard cells are convex and thin.
C. In grasses the guard cells are dumb bell shaped .
D. The trichomes are usually multicellular.

Answer

To determine which statement is incorrect, we will analyze each option provided in the question step by step.

### Step 1: Analyze the First Statement
**Statement:** Cuticle is present on the epidermis of both stems and roots.

**Analysis:**
- The cuticle is a protective layer found on the surfaces of stems and leaves, primarily to prevent water loss.
- However, roots typically do not have a cuticle because they are in direct contact with soil moisture.

**Conclusion:** This statement is **incorrect**.

### Step 2: Analyze the Second Statement
**Statement:** The outer walls of guard cells are convex and thin.

**Analysis:**
- Guard cells are specialized cells that control the opening and closing of stomata.
- The outer walls of guard cells are indeed convex and thinner than the inner walls, which allows them to change shape and regulate gas exchange.

**Conclusion:** This statement is **correct**.

### Step 3: Analyze the Third Statement
**Statement:** In grasses, the guard cells are dumbbell-shaped.

**Analysis:**
- In grasses, the guard cells do have a unique dumbbell shape, which is different from the kidney shape seen in many other plants.

**Conclusion:** This statement is **correct**.

### Step 4: Analyze the Fourth Statement
**Statement:** The trichomes are usually multicellular.

**Analysis:**
- Trichomes are hair-like structures on the surface of plants and can be unicellular or multicellular.
- However, many trichomes, especially those involved in water retention and protection, are indeed multicellular.

**Conclusion:** This statement is **correct**.

### Final Conclusion
After analyzing all statements, the only incorrect statement is the **first statement** regarding the presence of cuticle on roots.

### Summary of the Solution
- **Incorrect Statement:** Cuticle is present on the epidermis of both stems and roots.
- **Correct Statements:**
- The outer walls of guard cells are convex and thin.
- In grasses, the guard cells are dumbbell-shaped.
- The trichomes are usually multicellular.