What is a permanent tissue ? Classify permanent tissues and describe them. [5] marks
Answers
Answer:
Permanent Tissue
The tissues that are completely grown and has lost the ability of division are known as permanent tissues. The meristematic tissues divide and differentiate to form the permanent tissues.
permanent tissue
Types of Permanent tissue
Simple Permanent Tissue
Simple Permanent TissueThese are also known as homogenous tissues. They are made up of a single cell type, usually with the same origin, structure, and function.
Simple Permanent TissueThese are also known as homogenous tissues. They are made up of a single cell type, usually with the same origin, structure, and function.Simple permanent tissue is further classified into three types:
Parenchyma
The cells have an oval or round shape.
The cell wall is made up of hemicellulose or cellulose.
The cell is thin-walled.
The cells have vacuoles and very small nucleus.
It is found in all parts of the plant.
The protoplasm is living and dense.
Collenchyma
Cells are long and thick walled.
The cell wall is made up of cellulose and pectin.
It is the only tissue with the highest refractive index due to the presence of pectin.
It is found in hypodermis of dicot stem and the vascular bundle of dicot leaf.
The amount of chloroplast is less in the cells.
The cells have no intercellular spaces.
Sclerenchyma
These are dead tissues, very hard and rigid in texture.
Cells are thick walled with various size and shapes.
These provide mechanical support and rigidity to the plant.
Complex permanent Tissue
The complex tissues are made up of different types of cells performing diverse functions. These are of two types:
Xylem
It transports water and nutrients from the roots to the leaves of the plant.
It provides support to the plants.
It is divided into-tracheids, vessels, xylem fiber, and xylem parenchyma.
Phloem
It translocates the prepared organic food from the leaves to different parts of the plant.
It is also known as bast.
It is composed of sieve tubes, companion cells, phloem parenchyma, and phloem fibers.
Special Tissues
The special tissues are structurally modified to perform secretory functions. These are of two types:
Laticiferous Tissues
These plant tissues contain latex.
They originate from the meristematic tissues and mature with other tissues.
The cells are elongated, thin-walled and multinucleated.
These are found in a large number of families such as Apocynaceae, Euphorbiaceae, Compositate, etc.
Glandular Tissues
These consists of different glands which secrete resins, oil, mucilage, tannin, etc.
These glands are located on the epidermis.
Answer:
Permanent tissues are derived from meristematic tissue but their cells have lost the power of division and have attained their definite forms.
Permanent tissues are classified into the following two types:
1) Simple permanent tissue
2) Complex permanent tissue
a) Simple permanent tissues: These tissues are composed of cells which are structurally and
functionally similar.
- Simple permanent tissues are further classified into the following three types:
*Parenchyma: Parenchyma forms the bulk of the plant body. Parenchyma cells are living and possess the power of division.
*Collenchyma: Collenchyma tissue is also living. It is characterised by the deposition of extra cellulose at the corners of the cells.
*Sclerenchyma: Sclerenchyma cells are dead cells and they are devoid of protoplasm. The cell walls of sclerenchyma are largely thickened with deposition of lignin.
-Complex permanent tissues: The complex tissues consist of more than one type of cells
having a common origin. All these cells coordinate to perform a common function.
Complex tissues are of the following two types:
*Xylem: Xylem is a vascular and mechanical tissue. It is a conducting tissue. Xylem is composed of four different types of cells:
-Tracheids
-Vessels
-Xylem parenchyma
-Xylem sclerenchyma.
Except xylem parenchyma, all other xylem elements are dead and bounded by thick lignified walls.
*Phloem: Like xylem, phloem is also vascular but has no mechanical function. Phloem is composed of following four elements:
-Sieve tubes
-Companion cells
-Phloem parenchyma
-Phloem fibres.
Except phloem fibres, all other phloem elements are living.
Xylem and phloem are both conducting tissues and are also known as vascular tissues. Together, both of them constitute vascular bundle