Question

In which way collenchyma differs from sclerenchyma? (a) Retaining protoplasm at maturity (b) Having thick walls (c) Having wide lumen (d) Being meristematic

Short answer

Collenchyma differs from sclerenchyma in retaining protoplasm at maturity.

Step-by-step solution

Understanding collenchyma and sclerenchyma tissue

The first step is to understand the two types of tissue. Collenchyma is a type of plant tissue that is typically longer and have irregularly thickened corners. They often respond to the production of the mechanical tissue in regions of the plants stem where growth is still ongoing. Collenchymas cells have living protoplasm and may divide. Sclerenchyma is another variety of plant tissue. They are typically long, slim, tapering and thick-walled. Unlike collenchyma, sclerenchyma cells are dead at maturity and do not divide.

Matching the statements

In the next step, examine each of the provided statements and match them with the definitions of collenchyma and sclerenchyma. The statement (a) 'Retaining protoplasm at maturity', matches with collenchyma as they are living tissues. The statement (b) 'Having thick walls', could be associated with both since both can have thick walls. The statement (c) 'Having wide lumen', isn’t specifically related to either tissue type. Finally, statement (d) 'Being meristematic' doesn't apply particularly to either since both tissues aren't meristematic.

Comparing and finding differences

In the final step, look for the unique characteristic that distinguishes collenchyma from sclerenchyma based on the given options. In comparing these features, we find that the main difference lies in the fact that collenchyma retains protoplasm at maturity, where sclerenchyma does not.

Key concepts

Plant Tissue Types

Plants have a variety of tissue types that are specialized to carry out different functions essential for the plant’s growth, structural support, and survival.
Plant tissues can be broadly categorized into two main types: meristematic and permanent tissues.

• Meristematic tissues are found in the growing regions of plants and are responsible for plant growth. They have the capability to divide actively.
• Permanent tissues, on the other hand, are derived from meristematic tissues, but they lose the ability to divide and have specialized structures and functions. These are further divided into simple and complex tissues.

Simple tissues consist of cells that are similar in structure and function. The three types of simple tissues are parenchyma, collenchyma, and sclerenchyma. Complex tissues, like xylem and phloem, are made of different types of cells and are involved in the transport of water, nutrients, and food within the plant.

Characteristics of Collenchyma

Collenchyma is one of the three types of simple permanent tissues that offer flexibility and mechanical support to the plants, particularly in young stems, leaves, and petioles that are still elongating.
Here are some key characteristics of collenchyma cells:

• They have living protoplasm and can stay alive at maturity, unlike sclerenchyma cells.
• They are elongated cells with irregularly thickened corners.
• The walls of collenchyma cells are composed mainly of cellulose and pectin.
• Collenchyma provides tensile strength to the plant and can adapt to the increased growth by elongation.

The walls are unevenly thickened, mostly at the corners, which helps resist bending and provides flexibility. This characteristic allows them to play a crucial role in plant growth regions.

Properties of Sclerenchyma

Sclerenchyma, on the other hand, is known for providing the main structural support to various parts of the plant.
Distinguishing properties of sclerenchyma include:

• Cells are usually dead at maturity and lack living contents, which means they don't have protoplasm when they mature.
• These cells are long, slim, and tapering with extremely thickened secondary cell walls due to the presence of lignin—a complex organic polymer that adds rigidity and waterproofing benefits.
• The lumen, or inside space of the cell, is often quite reduced because of the thick cell walls.
• Sclerenchyma cells cannot divide and are often found in parts of the plant that have stopped growing.
• These cells add strength and support to parts of the plant that are no longer elongating, such as mature stems, seed coats, and the veins of leaves.

Because of their thick walls and supportive function, sclerenchyma tissues play an important role in plant durability and resistance to external stresses.