Problem 207 - Objective Biology for NEET

Question

Assertion: Collenchyma provides mechanical strength as well as elasticity. Reason: Wall thickening in collenchymas is not uniform.

Step-by-Step Solution

Answer

Both the assertion and the reasoning are correct and the reason is a correct explanation of the assertion.

Step 1: Understand the assertion and reasoning

The assertion is: 'Collenchyma provides mechanical strength as well as elasticity'. The reason is: 'Wall thickening in collenchymas is not uniform'. It's important to first understand these statements individually. Collenchyma cells indeed provide mechanical strength and elasticity to plants. Gradient and uneven thickening of cell wall is a key characteristic of collenchyma cells.

Step 2: Link the reasoning to the assertion

Next, examine whether the provided reason explains the assertion. The gradient and unevenly thickened wall of collenchyma provides mechanical strength to resist bending and breaking, as well as elasticity to the plant. The thick sections supply strength, while the thin parts offer flexibility.

Step 3: Determine the relationship

Based on these observations, it can be concluded that the assertion and the reasoning are true individually and the reason is a correct explanation for the assertion.

Key Concepts

Mechanical Strength in Plants

Plants need a sturdy structure to withstand various environmental factors like wind and rain. This is where the mechanical strength of plant tissues, such as collenchyma, comes into play. Collenchyma cells are specialized plant cells that provide added support to young, growing sections of the plant. This includes leaves and stems.

The mechanical strength offered by collenchyma comes from their unique structure. These cells are packed tightly together, forming a supportive tissue that helps maintain the plant's shape. Without such reinforcement, plants would struggle to stand upright and face environmental stressors effectively.

Here are some key points about mechanical strength in plants:

• Collenchyma cells support plant parts by forming closely knitted cell layers.
• The mechanical strength helps withstand natural forces like wind.
• It is particularly crucial during the growth phases of the plant.

Cell Wall Thickening

Cell wall thickening is an interesting adaptation found in collenchyma cells. It is an essential feature that contributes to both mechanical strength and flexibility in plants. In collenchyma, the cell walls are not thickened uniformly across the cell.

Uneven cell wall thickening means that some parts of the cell wall are thicker than others. This irregularity is what allows collenchyma cells to offer both support and flexibility. The thicker parts provide necessary rigidity while the thinner areas allow bending without breaking.

Key aspects of cell wall thickening include:

• Non-uniform thickening creates a balance between strength and flexibility.
• Helps collenchyma tissues adapt to dynamic environmental conditions.
• Crucial for plant parts that undergo mechanical stress.

Plant Tissue Elasticity

Elasticity is a critical property that enables plant tissues to recover their shape after deformation. Collenchyma contributes significantly to plant tissue elasticity, providing resilience to growing plant parts, especially in young and actively developing areas.

The role of collenchyma in providing elasticity is closely related to its uneven cell wall thickening. This feature allows cells to stretch slightly and return to their original shape without damage. Such flexibility ensures that plants can sway gently without snapping or incurring damage.

Some important points about plant tissue elasticity:

• Elasticity is vital for maintaining plant structure under mechanical stress.
• Collenchyma allows for slight stretching, aiding in growth and adaptability.
• It ensures plants can endure minor physical changes, like wind-induced movement.