Question

Explain the types of parenchyma tissues with their functions.

Answer 1

Plant tissues in which a group of similar cells present performing an organized function and are essential in various activities of plants such as cellular metabolism like photosynthesis, respiration, regeneration, etc. These cells provide elasticity, mechanical strength to organs.

Complete answer:
Parenchyma tissue, a type of simple permanent tissue that develops an important part of the ground tissues i.e. which is not a vascular tissue but a dermis (skin) of the plant part. Parenchyma tissues are non-vascular and they are composed of simple, living, and undifferentiated cells.
Structure of parenchyma cells: these cells are living and having a prominent nucleus with protoplast. Parenchymatous cells are polyhedral in shape, which may be oval, round. They are made up of a thin cell wall which is further developed from cellulose or hemicelluloses. They contain several vacuoles in which water is abundant and serves as a reservoir.

Depending upon their structures, functions, and location parenchyma cells can be differentiated into:

-Chlorenchyma cells;Those cells have chloroplast and carry out photosynthesis. These cells make up the mesophyll tissue of leaves and also present in the stem of certain plant species.
-Vascular parenchyma; Those parenchymatous cells which are associated with the vascular tissues, mainly of two types; (A) Phloem parenchyma – Made up of tapering, elongated, and cylindrical cells with having a dense cytoplasm, they store food like resins, latex, etc. (B) Xylem parenchyma- Made up of thin walled cells and the cell wall is developed from cellulose. These cells store food fats, starch as tannins, crystals.
-Prosenchyma cells; These cells are fiber-like elongated and are thick-walled. They provide rigidity and strength to the plant.
-Aerenchyma; They are present in the aquatic plants because these cells provide buoyancy to the floating plants. Very large intercellular spaces are present. They are important as they help in respiration by giving appropriate oxygen to the aquatic plants.
-Epidermis parenchyma; Present in the epidermis of the leaves of some gymnosperms. No intercellular spaces are present. They contain a cutinised cell wall.

Functions of parenchyma cell:-
Serves as a reservoir of water and food as large intracellular space is present. It can store water, food, oil droplets, etc.
These parenchymatous cells transport various nutrients and some other chemicals.
Parenchymatous cells have totipotency i.e. they can transform into other types of cells and serve as the precursor for other cells.

Note: Parenchyma cells also protect the plant from predators because these cells contain spiny
projections. The thickened wall of these cells provides turgidity to the plant. In the water stress condition cuticle present on the epidermis helps in the reduction of the rate of transpiration.