A narrow thin walled cell with large nucleus and lyging on the side of sieve tubes in absent in

Options

A. angiosperms
B. pteriodophytes
C. gymnosperms
D. both 2 and 3

Answer

To solve the question regarding the absence of a narrow thin-walled cell with a large nucleus lying on the side of sieve tubes, we can follow these steps:

### Step 1: Understand the Components of Phloem
Phloem is a type of vascular tissue in plants responsible for the transport of food (mainly sugars) from the leaves to other parts of the plant. The main components of phloem include:
- Sieve tube elements
- Companion cells
- Phloem parenchyma
- Phloem fibers

### Step 2: Identify the Cell in Question
The question refers to a "narrow thin-walled cell with a large nucleus" that is associated with sieve tubes. This description fits the **companion cells**, which are closely associated with sieve tube elements and help in their functioning.

### Step 3: Analyze the Options
The options provided are:
1. Angiosperms
2. Pteridophytes
3. Gymnosperms
4. Both 2 and 3 (Pteridophytes and Gymnosperms)

### Step 4: Determine the Presence of Companion Cells
- **Angiosperms**: These plants have both sieve tubes and companion cells. Therefore, the cell in question is present in angiosperms.
- **Gymnosperms**: These plants do not have companion cells; instead, they have albuminous cells associated with their sieve cells. Hence, the cell in question is absent in gymnosperms.
- **Pteridophytes**: Similar to gymnosperms, pteridophytes do not have companion cells associated with their sieve tubes. Thus, the cell in question is also absent in pteridophytes.

### Step 5: Conclusion
Since the narrow thin-walled cell with a large nucleus (companion cell) is absent in both gymnosperms and pteridophytes, the correct answer to the question is:
**Option D: Both 2 and 3 (Pteridophytes and Gymnosperms)**.

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