CBSE Class 9 Tissues. Learning the important concepts is very important for every student to get better marks in examinations. The concepts should be clear which will help in faster learning. The attached concepts made as per NCERT and CBSE pattern will help the student to understand the chapter and score better marks in the examinations.
1. Tissue is a group of cells having similar origin, structure& function. Study of tissues is called Histology
2. In unicellular organism (Amoeba) single cell performs all basic functions, whereas in multi-cellular organisms (Plants and Animals) shows division of labor as Plant tissue & Animal tissues.
3. Plant tissues are two types: Meristems & Permanent tissues.
4. Meristems: The Meristems are the tissues having the power of cell division. It is found on those region of the plant which grows.
5. Types of Meristems;
1. The Apical meristems – It is present at the growing tip of the stem and roots and increases the length.
2. The lateral meristems - present at the lateral side of stem anf root (cambium) and increases the girth.
3. The intercalary meristems - present at internodes or base of the leaves and increases the length between the nodes.
( Please refer to Fig. 6.2: location of meristems in plant body , NCERT Book Page- 69).
26. Permanent tissues: Two types such as Simple permanent tissues & Complex permanent tissues.
a) Simple permanent tissues: subdivided as
(i) Parenchyma: Tissues provide the support to plants.They are loosly packed and has large intracellular space.
- Parenchyma with chlorophyll which performs photosynthesis is called as chlorenchyma.
- The parenchyma with large air spaces to give buoyancy is called as aerenchyma .Parenchyma also stores food and water.
(ii) Collenchyma: Tissue provides mechanical support, thickened at the corners, have very little intercellular space. It allows easy bending of various parts of a plants without breaking
(iii) Sclerenchyma: Tissue makes the plant hard and stiff, thickened due to lignin and no intercellular space. Cells of this tissue are dead and commonly seen in the husk of coconut.
(iv) Guard cells& Epidermal tissue: the tissue aids in protection and exchange of gases. Guard cells kidney shaped in dicots, dumb bell shaped in monocots to guard the stomata. The epidermal tissues of roots aid in absorption of water and minerals. The epidermal tissues in desert plants have a thick waxy coating of Cutin with waterproof quality. The epidermal tissues form the several layer thick Cork or the Bark of the tree. (Please refer to Fig. 6.3- 6.6, NCERT Book Page-70-73).
b) Complex permanent tissues: The complex tissues are made of more than one type of cells. All these cells coordinate to perform a common function.
They are subdivided as;
Xylem: It consists of tracheids, vessels, xylem parenchyma and xylem fibers. The cells have thick walls,
Function - aids in conduction of water and minerals.
Phloem: It consists of sieve tubes, companion cells, phloem parenchyma, and phloem fibers.
Function - Phloem transports food material to other parts of the plants.
(Please refer to Fig. 6.7, NCERT Book Page-73).
6. Animal tissues: Sub divided as epithelial tissue, connective tissue, muscular tissue and nervous tissue.
i. Epithelial tissue: It is a protective covering forming a continuous sheet. Simple epithelium is the one which is extremely thin in one layer, whereas stratified epithelium are arranged in pattern of layers.
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