Science · Class 9 · Chapter 3

Tissues in Action

• Meristematic tissue — Actively dividing tissue responsible for growth.
• Differentiation — Meristematic cells becoming specialised.
• Parenchyma / Collenchyma / Sclerenchyma — Storage / flexible support / rigid support.
• Xylem / Phloem — Carries water up / carries food throughout.
• Epithelial tissue — Covers and lines the body and organs.
• Connective tissue — Connects and supports — blood, bone, cartilage.
• Neuron — The nerve cell that carries signals.
• Joint — A junction between bones.

Chapter 3 · Concept 1 of 9

Why Plant and Animal Tissues Differ

• Plants stay put — Fixed in place, plants need rigid cell walls for support — and different tissues for making and moving their own food.
• Animals move — Animal cells have no cell wall, keeping them flexible enough for locomotion — suited to digesting food rather than making it.

Chapter 3 · Concept 2 of 9

Meristematic Tissues

• Apical meristem — At root and shoot tips — causes growth in length.
• Lateral meristem — A ring around the stem — causes growth in girth, seen as tree rings.
• Intercalary meristem — At the base of internodes — lets grass and hedges regrow after cutting.

Chapter 3 · Concept 3 of 9

Simple Permanent Tissues

• | Cells | Function
• Parenchyma — Living, thin-walled — Storage, photosynthesis
• Collenchyma — Living, unevenly thickened corners — Flexible support — bends without breaking
• Sclerenchyma — Mostly dead, thick lignified walls — Rigidity and strength

Chapter 3 · Concept 4 of 9

Xylem and Phloem

• Xylem — Transports water and minerals upward from roots, and gives strength — made of tracheids, vessels, and fibres.
• Phloem — Transports food (sugars) throughout the plant — made of sieve tubes and companion cells that regulate them.

Chapter 3 · Concept 5 of 9

Plant Tissue Systems

• Dermal — Outer covering and protection — epidermis plus a waxy cuticle.
• Ground — The plant's bulk — parenchyma, collenchyma, sclerenchyma.
• Vascular — Transport — xylem and phloem together.

Chapter 3 · Concept 6 of 9

Epithelial and Connective Tissue

• Epithelial tissue — Forms outer coverings and linings of organs — tightly packed cells, adapted for protection, exchange, secretion, or absorption depending on where they are.
• Connective tissue — Connects and supports body parts — blood, bone, cartilage, tendons (muscle to bone), and ligaments (bone to bone).

Chapter 3 · Concept 7 of 9

Skeletal, Smooth, and Cardiac Muscle

• | Control | Shape | Found in
• Skeletal — Voluntary — Long, cylindrical, striated — Attached to bones
• Smooth — Involuntary — Spindle-shaped, unstriated — Stomach, intestines
• Cardiac — Involuntary, rhythmic — Branched, faintly striated — The heart only

Chapter 3 · Concept 8 of 9

Nervous Tissue and Joints

• Neurons — A cell body (with nucleus), dendrites (receive signals), and an axon (transmits signals) — forming the body's control network.
• Four joint types — Ball & socket (shoulder — free movement), hinge (elbow, knee — one direction), pivot (neck — rotation), and fixed (skull — none).

Chapter 3 · Concept 9 of 9

The Musculoskeletal System

• Bones, muscles, joints, cartilage, tendons, and ligaments together let us stand, move, and protect our organs.
• About 12–15% of body weight — The vertebral column supports the body and protects the spinal cord; the rib cage protects the heart and lungs, and expands and contracts for breathing.

Quick Recap

Check Your Understanding

1. 1Meristematic tissues divide repeatedly. What property of their cells allows this? (i) Thick walls (ii) Large vacuoles (iii) Thin walls, dense cytoplasm, large nucleus (iv) Functionally differentiated cells.
2. 2If a plant can't transport food from its leaves to its roots, which tissue is malfunctioning? (i) Xylem (ii) Phloem (iii) Epidermis (iv) Sclerenchyma.
3. 3Why are the epithelial tissues lining internal organs usually only one or a few cells thick? (i) To store food (ii) Maximum strength (iii) Quick exchange of materials (iv) To reduce friction.