Chapter 3 — Tissues in Action

Chapter 3 of Class 9 Science (NCERT 2026-27 'Exploration' edition) covers tissues in plants and animals — how groups of similar cells work together to perform specific functions, enabling division of labour and complex life processes.

Tissues in Action (Chapter 3, NCERT Class 9 Science 2026-27 'Exploration' edition) explains how similar cells group into tissues to enable division of labour. Plant tissues include meristematic tissues (apical, lateral, intercalary) responsible for growth in length, girth, and regrowth, and permanent tissues (parenchyma, collenchyma, sclerenchyma, xylem, phloem) for protection, support, and conduction. Animal tissues — epithelial, connective, muscular, and nervous — perform functions such as protection, transport, movement, and coordination. The musculoskeletal system, comprising bones, joints, cartilage, tendons, and ligaments, works under nervous system control to enable movement and protect organs.

1. 01Plant meristematic tissues (apical, lateral, intercalary) drive growth in length, girth, and regeneration after cutting respectively; their cells have thin walls, dense cytoplasm, large nucleus, and no vacuoles.
2. 02Permanent plant tissues are either simple (parenchyma — food storage/photosynthesis; collenchyma — flexibility; sclerenchyma — strength via lignin) or complex (xylem — water/mineral transport; phloem — food transport via sieve tubes).
3. 03The epidermis, covered by a waxy cuticle, forms the outermost protective layer of plants; stomata in leaves enable gaseous exchange and transpiration.
4. 04Animal tissues are of four main types: epithelial (body covering and lining), connective (blood, bone, cartilage, tendons, ligaments), muscular (skeletal, smooth, cardiac), and nervous (neurons that receive and transmit impulses).
5. 05Skeletal muscles are voluntary (striated, multinucleate, cylindrical fibres); smooth muscles are involuntary (spindle-shaped, single nucleus, non-striated); cardiac muscles are involuntary, branched, and work without fatigue.
6. 06The musculoskeletal system — bones, muscles, joints (ball-and-socket, hinge, pivot, fixed), cartilage, tendons, and ligaments — produces movement under nervous system control; the adult skeleton accounts for about 12–15% of body weight.