Short summary of chapter tissues class 9
Answers
Cells form groups cells that need to perform a single task often group together.
This grouping of cells together to perform a function efficiently is called a Tissue.
For Example, Muscles and Blood.
The tissue cells have the same structure and they perform the same function.
Meristematic Tissue
Only certain parts of a plant tend to grow. The tissues located in such parts are called meristematic tissues.
They have the capability to divide themselves and form new tissues. They have thin cell wall made of cellulose. Also have dense nucleus and cytoplasm but lack vacuoles.
They can further we classify differently based on the areas of the plants where they are located -
Apical
Lateral
Intercalary
Living organisms in this world comprise of cells.
There are unicellular as well as multicellular organisms present in this world.
In unicellular organisms, the only single cell is capable of performing several functions such as Respiration, Digestion and Clearing of the cell.
In multicellular organisms, there is a division of labor. There are different types as well as groups of cells that perform different functions in a multicellular organism. For Example, In animals muscle cells are responsible for causing movement, nerve cells are responsible for carrying messages and signals from one part of the body to another and blood is responsible for transportation of food and oxygen to different parts of the body.
In plants, there are vascular tissues that are responsible for carrying food and water two different parts of a plant.
The Formation of Tissues
Cells form groups cells that need to perform a single task often group together.
This grouping of cells together to perform a function efficiently is called a Tissue.
For Example, Muscles and Blood.
The tissue cells have the same structure and they perform the same function.
Tissues of Plants and Animals
Plant Tissues Animal Tissues
Plants do not move so their tissues are predominantly the ones that provide support to them so that they can stand erect.
Animals need more energy as compared to plants because they are not stationary. Their tissues are the ones that can support movement.
These tissues are made up of dead cells because dead cells can also provide mechanical strength to the plants and do not require much maintenance.
The tissues in case of animals are made up of living cells so that they can move and perform several functions.
Only certain parts of the plant can grow. The tissues present in such regions of and divide themselves and form new tissues.
Cells in animals grow uniform early and not only in certain regions of the body.
The structure of plant tissues is not very specialized as compared to animals
The organs and organ systems in animals are highly developed.
Plant Tissues
Types of Plant Tissues
Figure 1 Types of Plant Tissues
Meristematic Tissue
Only certain parts of a plant tend to grow. The tissues located in such parts are called meristematic tissues.
They have the capability to divide themselves and form new tissues. They have thin cell wall made of cellulose. Also have dense nucleus and cytoplasm but lack vacuoles.
They can further we classify differently based on the areas of the plants where they are located -
Apical
Lateral
Intercalary
Figure 2 Location of meristematic tissue
Apical Meristem Lateral Meristem Intercalary Meristem
They are responsible for the growth of stems and roots in the plants
They are found on the tips of the roots and stems.
They are responsible for increasing the circumference of the middle part of the stem and hence are found there.
These tissues are present at internodes or stem regions between the places at which leaves attach.
Why there are no vacuoles in the intercalary meristem?
Vacuoles are responsible for storage of food in water. The intercalary tissues do not store them. They are rather responsible for manufacturing them.
Moreover, vacuoles contain sap which provides rigidity to a cell. This property of vacuoles may not allow the intercalary tissues to divide and manufacture new cells. Hence vacuoles are not present in them.
Permanent Tissue
The cells that are formed by the meristematic tissues often have to take a certain role in the plant and thus, they lose their ability to divide and form more cells. They then become the permanent tissues of the plants.
Differentiation - The process by which cells of the meristematic tissues convert themselves into a permanent tissue by taking a fixed shape, size and function is called differentiation.
Types of Permanent Tissues:
Simple Permanent Tissues
Complex Permanent Tissues
Simple Permanent Tissues are of five types:
Parenchyma
Chlorenchyma
Aerenchyma
Collenchyma
Sclerenchyma
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