Chapter 18 of 25

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Tamil Nadu (TNBSE)Class 9 Science★ 4-5 marks in assessments

Organisation of Tissues

Samacheer Kalvi (TN State Board) Class 9 Science — Biology Chapter 18, Organisation of Tissues. Tissues are groups of cells working together. Understanding plant tissues (meristematic, xylem, phloem) and animal tissues (epithelial, muscle, nerve) explains plant growth, water conduction, organ functioning, and sensory responses. Notes, worked examples, common mistakes, and quick revision.

⏱ 19 min readMedium difficulty✓ Free · NCERT-aligned

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By the end of this chapter you'll be able to…

1Explain the difference between plant and animal tissues
2Describe types and functions of plant meristematic and permanent tissues
3Describe the structural features of epithelial, connective, muscular, and nervous tissues
4Explain division of labour in multi-cellular organisms

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Why this chapter matters

Tissues are groups of cells working together. Understanding plant tissues (meristematic, xylem, phloem) and animal tissues (epithelial, muscle, nerve) explains plant growth, water conduction, organ functioning, and sensory responses.

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Class 8 Science — Organisation of Life

Basic cell and organ concepts.

Organisation of Tissues — Class 9 Science (Samacheer Kalvi)

TN State Board (Samacheer Kalvi) Class 9 Science, Biology — Chapter 18. Tissues are groups of cells working together. Understanding plant tissues (meristematic, xylem, phloem) and animal tissues (epithelial, muscle, nerve) explains plant growth, water conduction, organ functioning, and sensory responses.

1. About this chapter

This chapter explores the organization of plant tissues (meristems, vascular elements) and animal tissues (epithelial, connective, muscular, nervous).

2. Plant Tissues

Meristematic Tissues: Actively dividing cells, thin walls, dense cytoplasm, no vacuoles. Found at tips (apical), sides (lateral), and nodes (intercalary).
Simple Permanent Tissues:
- Parenchyma: Thin-walled, storage cells; chlorenchyma (photosynthesis), aerenchyma (buoyancy in aquatics).
- Collenchyma: Provides flexibility, thickened corners.
- Sclerenchyma: Thick lignified dead cells, strength (fibers, sclereids).
Complex Permanent Tissues:
- Xylem: Conducts water/minerals (vessels, tracheids).
- Phloem: Conducts food (sieve tubes, companion cells).

3. Animal Tissues

Epithelial Tissue: Protective outer sheet (squamous, cuboidal, columnar, ciliated).
Connective Tissue: Binds and supports (bone, cartilage, blood, adipose, areolar).
Muscular Tissue: Supports movement. Striated (skeletal, voluntary), Non-striated (smooth, involuntary), Cardiac (heart, involuntary striated).
Nervous Tissue: Neurons transmitting impulses.

Key formulas & results

Everything you need to memorise, in one card. Screenshot this for revision.

Tissue Hierarchy

Cells -> Tissues -> Organs -> Organ Systems

Found in multicellular organisms.

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Common mistakes & fixes

These are the exact errors that cost students marks in board exams. Read them once, save yourself the trouble.

WATCH OUT

✗ Confusing xylem and phloem functions.

✓ Xylem conducts water and mineral salts unidirectionally (upward). Phloem conducts food (organic solute) bidirectionally (leaves to other parts).

WATCH OUT

✗ Thinking meristematic tissues store food.

✓ Meristematic tissues are actively dividing cells with thin walls and no vacuoles. Permanent tissues like parenchyma perform storage.

NCERT exercises (with solutions)

Every NCERT exercise from this chapter — what it covers and how many questions to expect.

Multiple Choice Questions

Questions on xylem components, epithelial types, and neuron parts.

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Short Answer Questions

Meristem features, xylem vs phloem, cardiac muscle properties, and neuron diagram.

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Practice problems

Try each one yourself before tapping "Show solution". Active recall > rereading.

Q1EASY· Concept

What is a tissue? Differentiate plant and animal tissues.

▶ Show solution

A tissue is a group of similar cells performing a specific function. Plant tissues are mostly dead/supportive and stationary. Animal tissues are living, consume more energy, and support active movement.

Q2MEDIUM· Structure

Draw a labelled diagram of a Neuron.

▶ Show solution

A neuron consists of: 1. Cyton (cell body) with nucleus. 2. Dendrites (short branching projections). 3. Axon (long single projection covered with myelin sheath).

5-minute revision

The whole chapter, distilled. Read this the night before the exam.

•Plants: Meristematic (dividing) and Permanent (fixed).
•Permanent: Simple (parenchyma, collenchyma, sclerenchyma) and Complex (xylem, phloem).
•Animals: Epithelial (protection), Connective (support), Muscular (movement), Nervous (control).
•Neuron is the unit of nervous tissue.

Tamil Nadu (TNBSE) marks blueprint

Where the marks come from in this chapter — so you can plan your prep.

Typical chapter weightage: 4-5 marks in assessments

Question type	Marks each	Typical count	What it tests
MCQ	1	1-2	Base concepts and definitions
Short Answer	2-3	1-2	Descriptive and application points

Prep strategy

Understand core definitions and solve standard textbook problems.
Review common mistakes to avoid losing easy marks.

Where this shows up in the real world

This chapter isn't just an exam topic — it lives in the world around you.

Horticulture

Plant tissue culture takes advantage of meristematic cells' totipotency to grow thousands of disease-free clones.

Medical Pathology

Biopsy examinations identify abnormal tissue growth (cancerous epithelial cells) to diagnose diseases.

Exam strategy

Battle-tested tips from teachers and toppers for this chapter.

Write definitions precisely as defined in the textbook.
Draw neat, labeled diagrams for biology and physics chapters.

Going beyond the textbook

For olympiad aspirants and curious learners — topics that build on this chapter.

Read advanced reference materials to explore concepts beyond the school syllabus.

Where else this chapter is tested

CBSE board isn't the only one — other exams test this chapter too.

Class 9 Annual ExamsHigh

NTSE Stage 1Medium

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Questions students ask

The real ones — pulled from the Q&A community and tutor sessions.

Tissues made of actively dividing cells found in growing regions of plants (shoot/root tips, cambium).

It is an involuntary, striated muscle found only in the heart wall that contracts and relaxes rhythmically without fatigue throughout life.

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