Refer to the given dichotomous key and answer the following questions.
I. (a) The cells of tissue have walls. - Go to II
(b) The cells of tissue do not possess wall. - Go to III
II. (a) Tissue made of one type of cells. - Go to IV
(b) Tissue, made of more than one type of cells. - Go to V
III. (a) The tissue lines the alveoli of lungs. -P
(b) The tissue forms shock absorbing cushion around some vital organs. - Q
IV. (a) Cells of tissue contain air cavities and it provides buoyancy. -R
(b) The tissue provides mechanical strength and flexibility to young dicot stems and petioles. - S
V. (a) Tissue conducts water. - T
(b) Tissue conducts organic solutes. - U
Select the incorrect option regarding tissues P, Q, R, S, T and U.

Options

A. P is an epithelial tissue whereas Q is a loose connective tissue.
B. T is either greatly reduced or absent but R is exclusively present in aquatic floating plants whereas S is found in Cucurbita stems.
C. R is aerenchyma, S is collenchyma, T is xylem and U is phloem.
D. U is found in grit of guava, pear, etc., whereas the matrix of tissue P contains a flexible material called chondrin.

Answer

To solve the question regarding the dichotomous key and the tissues P, Q, R, S, T, and U, we will follow these steps:

### Step 1: Analyze the Key
- The key starts with whether the cells of the tissue have walls or not.
- If they have walls, we proceed to II; if not, we go to III.

### Step 2: Tissue Identification
1. **For Tissue P:**
- The cells have walls (go to II).
- Tissue made of one type of cell (go to IV).
- Cells contain air cavities and provide buoyancy (this describes **R**, which is a type of parenchyma).

2. **For Tissue Q:**
- The cells have walls (go to II).
- Tissue made of more than one type of cell (go to V).
- This tissue forms a shock-absorbing cushion around some vital organs (this describes **Q**, which is loose connective tissue).

3. **For Tissue R:**
- The cells have walls (go to II).
- Tissue made of one type of cell (go to IV).
- Cells contain air cavities and provide buoyancy (this is **R**, parenchyma).

4. **For Tissue S:**
- The cells have walls (go to II).
- Tissue made of one type of cell (go to IV).
- Provides mechanical strength and flexibility to young dicot stems and petioles (this describes **S**, which is collenchyma).

5. **For Tissue T:**
- The cells do not possess walls (go to III).
- This tissue conducts water (this describes **T**, which is xylem).

6. **For Tissue U:**
- The cells do not possess walls (go to III).
- This tissue conducts organic solutes (this describes **U**, which is phloem).

### Step 3: Identify the Incorrect Option
Now we need to determine which of the options regarding tissues P, Q, R, S, T, and U is incorrect.

- **P**: Squamous epithelial tissue (correct).
- **Q**: Loose connective tissue (correct).
- **R**: Parenchyma (correct).
- **S**: Collenchyma (correct).
- **T**: Xylem (correct, but it is greatly reduced or absent in some cases).
- **U**: Phloem (correct).

### Conclusion
The incorrect statement relates to tissue **T** (xylem) being greatly reduced or absent in some cases. This makes option T the incorrect option regarding the tissues.

### Final Answer
The incorrect option regarding tissues P, Q, R, S, T, and U is **T**.

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