Tissues — Plant and Animal
1. What Is a Tissue?
A TISSUE is a GROUP of SIMILAR cells that work together to perform a SPECIFIC function.
Levels of Organisation
Cell → Tissue → Organ → Organ System → Organism
2. Plant Tissues
A. Meristematic Tissues
Cells that DIVIDE actively. Found in growing regions.
Characteristics:
- Cells are SMALL, THIN-WALLED, with large nuclei.
- NO intercellular spaces.
- Vacuoles are ABSENT or very small.
Types:
| Type | Location | Function |
|---|---|---|
| Apical meristem | Tip of root and stem | Increases LENGTH |
| Lateral meristem | Sides of stem and root | Increases THICKNESS (girth) |
| Intercalary meristem | Base of leaves or nodes | Growth in some plants (grasses) |
B. Simple Permanent Tissues
| Tissue | Cell Type | Function | Location |
|---|---|---|---|
| Parenchyma | Living, thin-walled, loosely packed | Storage (food, water), photosynthesis | All plant parts |
| Collenchyma | Living, irregularly thickened corners | FLEXIBLE support (bending without breaking) | Stems, leaf stalks |
| Sclerenchyma | Dead, very THICK walls (lignin) | STRONG support (rigid) | Stems, seed coats, husks |
C. Complex Permanent Tissues — Vascular Tissues
| Tissue | Direction | Components | Function |
|---|---|---|---|
| Xylem | UPWARD only | Vessels, tracheids, xylem fibres, xylem parenchyma | Water and mineral transport |
| Phloem | UP and DOWN | Sieve tubes, companion cells, phloem fibres, phloem parenchyma | Food transport |
3. Animal Tissues
A. Epithelial Tissue (Covering Tissue)
Covers body surfaces, lines cavities, and forms glands.
| Type | Description | Location |
|---|---|---|
| Squamous | Flat, thin cells (one layer) | Skin lining, blood vessels |
| Cuboidal | Cube-shaped cells | Kidney tubules, glands |
| Columnar | Tall, pillar-like cells | Stomach, intestine lining |
| Ciliated | Columnar cells with HAIR-LIKE cilia | Respiratory tract |
| Stratified | Multiple layers of cells | Outer skin |
B. Connective Tissue (Binds and Supports)
| Tissue | Function | Location |
|---|---|---|
| Blood | Transport of O₂, nutrients, wastes | Blood vessels |
| Bone | Skeletal support, protection | Skeleton |
| Cartilage | Flexible support, reduces friction | Ear, nose, joints |
| Ligament | Connects bone to bone | Joints |
| Tendon | Connects muscle to bone | Musculoskeletal system |
| Areolar tissue | Fills spaces between organs | Under skin, around organs |
| Adipose tissue | Stores fat, insulation | Under skin, around organs |
C. Muscular Tissue (Movement)
| Type | Location | Control | Features |
|---|---|---|---|
| Striated (Skeletal) | Attached to bones | VOLUNTARY | Striped appearance |
| Smooth (Involuntary) | Walls of organs (stomach, intestine) | INVOLUNTARY | No stripes |
| Cardiac | Heart ONLY | INVOLUNTARY | Striped, branched |
D. Nervous Tissue (Control and Coordination)
- Made of NEURONS (nerve cells).
- Function: Receive and TRANSMIT electrical signals.
- Location: Brain, spinal cord, and nerves.
4. Comparison: Plant vs Animal Tissues
| Feature | Plant Tissues | Animal Tissues |
|---|---|---|
| Growth | Throughout life (meristems) | Stops after maturity |
| Cell walls | Present (cellulose) | Absent |
| Vacuoles | Large (mature cells) | Small or absent |
| Movement | No movement | Many tissues can move |
| Support | Cell walls + sclerenchyma | Bone, cartilage |
| Living/dead at maturity | Many dead (sclerenchyma, xylem vessels) | Mostly living |
5. ICSE Exam Focus
| Topic | Marks | Frequency |
|---|---|---|
| Types of plant tissues (simple) | 2-3 marks | Very High |
| Xylem and phloem functions | 2 marks | Very High |
| Animal tissue types | 3 marks | High |
| Epithelial tissue types | 2 marks | Medium |
| Comparison of plant vs animal tissues | 2 marks | Medium |
Common Mistakes
- Writing 'sclerenchyma provides flexibility' — WRONG (collenchyma is flexible, sclerenchyma is rigid).
- Confusing xylem (water) and phloem (food) transport direction.
- Saying all plant cells are living (sclerenchyma and xylem vessels are DEAD at maturity).
- Confusing ligament (bone-bone) with tendon (muscle-bone).
Self-Test (5 Questions)
Q1. Which plant tissue provides FLEXIBLE support? (1 mark)
- A) Parenchyma
- B) Collenchyma
- C) Sclerenchyma
- D) Xylem
Q2. 'Which animal tissue connects muscle to bone?' (1 mark)
Q3. 'Name the tissue that transports food in plants.' (1 mark)
Q4. 'Differentiate between xylem and phloem.' (2 points) (2 marks)
Q5. 'Name the three types of muscular tissue and give one location for each.' (3 marks)
Answers
A1. B) Collenchyma. A2. Tendon. A3. Phloem. A4. Xylem: transports water and minerals UPWARD; cells dead at maturity. Phloem: transports food UP and DOWN; cells living at maturity. A5. Striated (attached to bones / skeletal). Smooth (walls of internal organs like stomach/intestine). Cardiac (heart walls).
