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Class 9 Biology | Chapter 2: Tissues (Part 1) 1. Introduction Atissue is a group of cells that are similar in structure and/or work together to achieve a particular function. Plants and animals have different tissues because of their different lifestyles (plants are stationary, animals move). 2. Plant Tissues A. Meristematic Tissue Dividing tissue present at specific growth regions. They have thin walls, dense cytoplasm, and lack vacuoles. + Apical Meristem: At growing tips of stems/roots. Increases length. + Lateral Meristem (Cambium): Increases girth (width) of stem/root. « Intercalary Meristem: At base of leaves or internodes. Helps in growth of parts. 3. Permanent Tissue Formed when meristematic cells lose the ability to divide and take up a specific role (Differentiation). Simple Permanent Tissues (One type of cell) Type Features Function Live cells, thin walls, large intercellular Storage of food. If chlorophyll is present = Chlorenchyma. If air cavities Parenchyma spaces. present = Aerenchyma. Live cells, thickened at corners, little Collenchyma | bh " Provides flexibility and mechanical support space. Dead cells, long and narrow, thick Sclerenchyma ql Provides strength and stiffness (e.g., coconut husk). ‘walls (Lignin). Protective Tissue + Epidermis: Single layer of cells covering the plant. Secretes waxy layer. + Stomata: Small pores in leaf epidermis for gas exchange and transpiration. Guarded by kidney-shaped guard cells. + Cork: Older epidermis replaced by dead cork cells with Suberin (impervious to water/gas). Class 9 Biology | Chapter 2: Tissues (Part 2) Complex Permanent Tissues (Multiple cell types) Xylem: Conducts water/minerals. Phloem: Conducts food * Tracheids & Vessels (Dead, transport) *« Sieve tubes & Companion cells + Xylem Parenchyma (Storage) + Phloem Parenchyma * Xylem Fibres (Support) + Phloem Fibres (Dead) 4. Animal Tissues |. Epithelial Tissue Covering or protective tissues. Cells are tightly packed with no intercellular spaces. « Squamous: Thin, flat (Lining of mouth, esophagus). * Stratified Squamous: Many layers to prevent wear/tear (Skin). * Columnar/Ciliated: Pillar-like (Intestine/Respiratory tract). * Cuboidal: Cube-shaped (Kidney tubules, salivary glands). Il. Connective Tissue Cells are loosely spaced and embedded in an intercellular matrix. + Blood: Fluid matrix (plasma) with RBCs, WBCs, and platelets. Transports gases/food. + Bone: Hard matrix (Calcium/Phosphorous). Forms the skeleton. * Ligament: Connects Bone to Bone. * Tendon: Connects Muscle to Bone. + Areolar: Fills space inside organs; supports internal organs. + Adipose: Stores fats; acts as an insulator. Ill. Muscular Tissue Striated (Skeletal) Smooth (Involuntary) Cardiac (Heart) Voluntary, long, cylindrical, Involuntary, spindle-shaped, Involuntary, branched, cylindrical, multinucleated. uninucleated. uninucleated. 
