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Q.
Cells of permanent tissue are specialized -
NTA AbhyasNTA Abhyas 2020
Solution:
Plants contain two types of tissue-(a) Meristematic and (b) Permanent tissue. Meristematic tissue or meristem is a simple tissue composed of a group of similar and immature cells that have the capability of division. Permanent tissue contains nondividing cells. The cells have attained a permanent specialized shape, size, and function due to differentiation. These cells derived from meristematic cells. They have intercellular space and a large vacuole. They mainly help in supporting the plant, photosynthesis, conduction of water, and food. They can be living or dead. Depending on the composition, they are of two types (i) Simple and (ii) Complex permanent tissue. (i) Simple permanent tissue consists of one type of cells only. These tissues can be classified into three types: (a) Parenchyma- These are thin-walled living tissue. Their main function to store food. Parenchyma is present in all soft regions of the plant. (b) Collenchyma- These are living tissue with elongated structures. They have a deposition of hemicellulose or pectocelluose in the corner of the cell wall. No intercellular space is present in these tissues. collenchyma usually found in petioles below the epidermis where they provide strength along with flexibility. (c) Sclerenchyma- They are dead and have a thick deposition of lignin in the cell wall. No intercellular space is present. The main function of sclerenchyma is to provide mechanical strength to the plant part. They are found in the hard covering of seed coat, girt of fruit such as pear, and also in vascular tissue.
(ii) Complex permanent tissue- These are made up of different types of cells and they coordinate to perform the same function. They are two types: (a) Xylem- It is responsible for the conduction of water and mineral from root to shoot. (b) Phloem- It is responsible for the conduction of prepared food from leaves to other regions.
