Question

What is simple permanent tissue?

Answer 1

Simple permanent tissues :

1. A simple permanent tissue is a tissue that is made up of similar permanent cells that carry out the same function or a similar set of functions.
2. Simple permanent tissues are of three types :
   

(I) Parenchyma:

1. Parenchyma is a simple permanent living tissue that is made up of thin-walled similar isodiametric cells
2. They may be oval, rounded, or polygonal in outline
3. The cell wall is made up of cellulose
4. Cells may be closely packed or have small intercellular spaces for the exchange of gases. Internally each cell encloses a large central vacuole and a peripheral cytoplasm containing a nucleus
5. The adjacent parenchyma cells are connected by plasmodesmata.
6. The typical parenchyma is meant for the storage of food, slow conduction of various substances, and for providing turgidity to the softer parts of the plants.
   

(II) Collenchyma :

1. Collenchyma is a simple permanent tissue of refractile non-lignified living cells which possess pesto-cellulose thickenings in specific areas of their walls
2. The cells are often elongated. They are circular, oval, or angular in the transverse section. Each cell possesses a large central vacuole and a peripheral cytoplasm.
3. Wall possesses uneven longitudinal thickenings in specific areas.
   

(Ill) Sclerenchyma :

1. Sclerenchyma is a simple supportive tissue of highly thick-walled cells with little or no protoplasm
2. The cell cavities are narrow. The thickening of the wall is made up of cellulose or lignin or both
3. Sclerenchyma is of two types- Sclerenchyma fibers and Sclereids.
   (i) Sclerenchyma fibers: The sclerenchyma fibers are highly elongated, narrow, and spindle-shaped thick-walled cells with pointed or oblique end walls. The adjacent fibers possess simple oblique pits. Sclerenchyma fibers constitute the major mechanical tissue of plants because they can bear compression, pull, bending, and shearing.
   (ii) Sclereids: They are highly thickened dead sclerenchyma cells with very narrow cavities. Sclereids are broader as compared to the fibers being isodiametric polyhedral, short or cylindrical.