Understanding Plant Tissues with Living Cells

Plant tissues are groups of cells that perform a specific function. They can be broadly classified based on whether the cells are actively dividing or not, and whether the cells are living or dead at maturity. The question asks us to identify a pair of plant tissues where the cells are typically living.

Types of Permanent Plant Tissues

Let's look at the characteristics of the tissues mentioned in the options:

• Parenchyma: These are simple permanent tissues composed of relatively unspecialized cells with thin cell walls. Parenchyma cells are generally living at maturity. They are involved in various functions like storage, photosynthesis, and secretion.
• Collenchyma: These are also simple permanent tissues. Collenchyma cells are living at maturity and have thickened corners due to the deposition of pectin and cellulose. They provide mechanical support, particularly to growing stems and petioles.
• Sclerenchyma: This is another type of simple permanent tissue. Sclerenchyma cells are typically dead at maturity. Their cell walls are heavily thickened and lignified, providing rigid mechanical support and strength to the plant. Examples include fibers and sclereids.
• Tracheids: These are components of complex permanent tissues, specifically xylem. Tracheids are elongated, tube-like cells with lignified walls and are dead at maturity. They are primarily involved in the transport of water and minerals and provide mechanical support.

Identifying Tissues with Living Cells

Based on the characteristics described:

• Parenchyma cells are living.
• Collenchyma cells are living.
• Sclerenchyma cells are dead.
• Tracheid cells (part of xylem) are dead.

The question asks for a pair of tissues where the cells are living.

Analyzing the Options

Let's examine the given pairs:

• Parenchyma (Living) and Sclerenchyma (Dead) - This pair contains one living and one dead tissue type.
• Sclerenchyma (Dead) and Tracheids (Dead) - This pair contains two dead tissue types.
• Collenchyma (Living) and Sclerenchyma (Dead) - This pair contains one living and one dead tissue type.
• Parenchyma (Living) and Collenchyma (Living) - This pair contains two living tissue types.

Therefore, the cells of Parenchyma and Collenchyma tissues are living cells.

Revision Table: Key Plant Tissue Characteristics

Additional Information: Simple vs. Complex Permanent Tissues

Permanent tissues are those whose cells have lost the ability to divide and have taken up a permanent form and function. They can be classified into:

• Simple Permanent Tissues: These are made up of only one type of cell. Parenchyma, Collenchyma, and Sclerenchyma are examples of simple permanent tissues.
• Complex Permanent Tissues: These are made up of more than one type of cell working together as a unit. Xylem and Phloem are examples of complex permanent tissues. Xylem includes tracheids, vessels, xylem parenchyma, and xylem fibers. Phloem includes sieve tubes, companion cells, phloem parenchyma, and phloem fibers.

Understanding whether the cells of these tissues are living or dead is crucial to understanding their functions in the plant body.