What is meristem? Can I write the defination of Meristematic tissue in this question????
Answers
The term meristem was given by Carl Wilhelm von Nägeli. Meristematic tissues contain undifferentiated cells which are the building blocks of the specialized plant structures. These cells are present in the zone called meristem and can divide actively.
Meristematic tissues contain living cells with varied shapes. They possess a large nucleus devoid of the vacuole. The cells have no intercellular space. The size of the cells is very small and can divide effectively.
Meristematic Tissue
Characteristics of Meristematic Tissue
The characteristics of meristematic tissue are as follows:
The cells of the meristematic tissue are commonly called meristems.
The cells of the meristematic tissue have the quality of self-renewal. Every time the cell divides, one cell remains identical to the parent cell and the others form specialized structures.
They have very small and few vacuoles.
They are living and thin-walled.
The protoplasm of the cells is very dense.
The meristematic cells heal the wounds of an injured plant.
The cells of the meristematic tissues are young and immature.
The cells do not store food.
They exhibit a very high metabolic activity.
They possess a single, large and prominent nucleus.
Types of Meristematic Tissue
The meristematic tissues are of the following types:
On the basis of Origin
Promeristem
The earliest and youngest meristematic tissue.
It originates from the embryo.
The primary meristem arises from the promeristem.
It is found in the root and the shoot tips.
Primary Meristem
It arises from the promeristem.
Cells divide actively.
It is present below the promeristem and forms the permanent tissue.
Secondary Meristem
It originates from the primary meristem.
The permanent tissue forms from the secondary meristem.
On the Basis of Position
Apical Meristem
These are present at the tips of the roots and shoots and help in the increase in height of the plants.
Various cell divisions facilitate the growth of the cells in the roots and shoots. and help in cellular enlargement.
Apical meristem is divided into-promeristem zone which contains actively dividing cells, and the meristematic zone which contains protoderm, procambium, and ground meristem.
Intercalary Meristem
It is located in the leaves and internodes at the intercalary position.
These help to increase the length of the internode.
It is found in grass, monocots, and pines.
It is a part of apical meristem and adds to the height of the plant.
Lateral Meristem
It is located in the stems and roots on the lateral side.
It increases the thickness of the plant.
Vascular cambium and cork cambium are the two lateral meristems.
These divide periclinically or radially and give rise to secondary permanent tissues.
On the Basis of Function
Protoderm
It is the outermost plant tissue and forms the epidermis.
It protects the plants from any mechanical shocks.
Procambium
It is the innermost tissue and gives rise to xylem and phloem.
It helps in the transport of water and nutrients to different parts of the plant.
Ground Meristem
The cells are large with thick walls.
It forms the cortex, pericycle, and pith.
The meristematic tissues are usually found in the apices of the root systems and the shoots and are in a continuous state of division.
I hope you understand.
Answer:
The term meristem was given by Carl Wilhelm von Nägeli. Meristematic tissues contain undifferentiated cells which are the building blocks of the specialized plant structures. These cells are present in the zone called meristem and can divide actively.
Meristematic tissues contain living cells with varied shapes. They possess a large nucleus devoid of the vacuole. The cells have no intercellular space. The size of the cells is very small and can divide effectively.
Meristematic Tissue
Characteristics of Meristematic Tissue
The characteristics of meristematic tissue are as follows:
The cells of the meristematic tissue are commonly called meristems.
The cells of the meristematic tissue have the quality of self-renewal. Every time the cell divides, one cell remains identical to the parent cell and the others form specialized structures.
They have very small and few vacuoles.
They are living and thin-walled.
The protoplasm of the cells is very dense.
The meristematic cells heal the wounds of an injured plant.
The cells of the meristematic tissues are young and immature.
The cells do not store food.
They exhibit a very high metabolic activity.
They possess a single, large and prominent nucleus.
Types of Meristematic Tissue
The meristematic tissues are of the following types:
On the basis of Origin
Promeristem
The earliest and youngest meristematic tissue.
It originates from the embryo.
The primary meristem arises from the promeristem.
It is found in the root and the shoot tips.
Primary Meristem
It arises from the promeristem.
Cells divide actively.
It is present below the promeristem and forms the permanent tissue.
Secondary Meristem
It originates from the primary meristem.
The permanent tissue forms from the secondary meristem.
On the Basis of Position
Apical Meristem
These are present at the tips of the roots and shoots and help in the increase in height of the plants.
Various cell divisions facilitate the growth of the cells in the roots and shoots. and help in cellular enlargement.
Apical meristem is divided into-promeristem zone which contains actively dividing cells, and the meristematic zone which contains protoderm, procambium, and ground meristem.
Intercalary Meristem
It is located in the leaves and internodes at the intercalary position.
These help to increase the length of the internode.
It is found in grass, monocots, and pines.
It is a part of apical meristem and adds to the height of the plant.
Lateral Meristem
It is located in the stems and roots on the lateral side.
It increases the thickness of the plant.
Vascular cambium and cork cambium are the two lateral meristems.
These divide periclinically or radially and give rise to secondary permanent tissues.
On the Basis of Function
Protoderm
It is the outermost plant tissue and forms the epidermis.
It protects the plants from any mechanical shocks.
Procambium
It is the innermost tissue and gives rise to xylem and phloem.
It helps in the transport of water and nutrients to different parts of the plant.
Ground Meristem
The cells are large with thick walls.
It forms the cortex, pericycle, and pith.
The meristematic tissues are usually found in the apices of the root systems and the shoots and are in a continuous state of division.
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