Question

Which one of the following is not a characteristic of plant cells in the phase of elongation ?

• A. Large conspicuous nuclei
• B. Increased vacuolation
• C. Cell enlargement
• D. New cell wall deposition

Hint:

Meristematic cells are the "active babies"—they have huge nuclei and dense cytoplasm. Elongating cells are "teenagers"—they get taller and fill up with vacuoles!

Answer 1

The Correct Option is A

Step 1 : Understanding the Question:
The question focuses on the developmental zones of plant growth—specifically the phase of elongation. We must identify which characteristic provided in the options is not a typical feature of cells in this specific growth stage.
Step 2 : Key Formulas and Approach:
Growth in plants is divided into three consecutive phases:
1. Meristematic phase: Zone of constant cell division.
2. Elongation phase: Zone where cells increase in volume.
3. Maturation phase: Zone where cells reach structural finality.
The approach is to differentiate the cytological properties of a "dividing" cell from an "expanding" cell.
Step 3 : Detailed Explanation:
Dynamics of the Elongation Phase: Cells that are located proximal to the meristematic zone enter the phase of elongation. The primary physiological goal during this stage is a rapid increase in cell size and volume to facilitate the lengthening of the root or shoot.
Increased Vacuolation (B): As a cell expands, small vacuoles fuse to form a large central vacuole. The turgor pressure within this expanding vacuole drives the physical stretching of the cell. This is a hallmark of elongation.
Cell Enlargement (C): This is the defining feature of the phase. The cells physically grow in length and diameter, which allows for the rapid growth characteristic of this region.
New Cell Wall Deposition (A): To accommodate the increased surface area without the wall becoming too thin and prone to bursting, the cell must synthesize and deposit new cellulosic material into its wall.
The Exception - Nuclei (D): Large, conspicuous nuclei and dense protoplasm are primary characteristics of the meristematic phase. In the elongation phase, because the vacuole occupies most of the cell's space, the nucleus becomes relatively less prominent and is often pushed to the periphery.