Chapter 3 · ICSE Class 9 Biology (Selina Concise)

Tissues: Plant and Animal Tissues

Groups of similar cells doing one job: meristematic, permanent, epithelial, connective, muscular, nervous.

🧬 Chapter 3

Classification of tissues Plant tissues: meristematic and permanent, simple and complex. Animal tissues: epithelial, connective, muscular, nervous. Plant tissues Animal tissues Meristematic Permanent Apical Lateral Intercalary Simple Complex Parenchyma Collenchyma Sclerenchyma Xylem Phloem Epithelial (covering and lining) Connective (supports and joins) Muscular (movement) Nervous (carries impulses) Meristems divide to make new cells; permanent tissue has stopped dividing and has a fixed job.

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3.1

Plant tissues

A tissue is a group of similar cells doing a common job. Meristematic tissue keeps dividing: apical (growth in length), lateral (growth in girth) and intercalary (growth at the base of leaves or internodes, as in grasses). Permanent tissue has stopped dividing. Simple permanent tissues: parenchyma (living, thin-walled; storage, and photosynthesis in chlorenchyma), collenchyma (living, extra cellulose at corners; flexibility), sclerenchyma (dead, lignified; strength). Complex tissues: xylem carries water and minerals upward; phloem carries prepared food.

1

Which tissue makes a stem grow longer? Which makes it thicker?

Apical meristem makes it longer; lateral meristem (cambium) makes it thicker.

2

Why can we bend a young stem but not break it easily, while coconut husk fibres are strong?

Collenchyma gives flexibility. Sclerenchyma fibres are dead, thick-walled and lignified, giving strength.

3

Name the conducting cells of (a) xylem, (b) phloem.

(a) Tracheids and vessels. (b) Sieve tubes (helped by companion cells).

3.2

Animal tissues

Epithelial tissue covers and lines surfaces (squamous, cuboidal, columnar, ciliated, glandular). Connective tissue supports and joins: blood, bone, cartilage, tendon (muscle to bone), ligament (bone to bone), areolar and adipose (fat). Muscular tissue contracts: skeletal (striped, voluntary), smooth (involuntary) and cardiac (heart, involuntary). Nervous tissue is made of neurons that carry impulses.

1

Differentiate tendon and ligament.

A tendon joins muscle to bone. A ligament joins bone to bone.

2

Which muscle never gets tired and works without our control?

Cardiac muscle, found only in the heart.

3

Name the three main parts of a neuron.

Cell body (cyton), dendrites and axon.

Practice

Exercises

1. Define a tissue.

2. Name the three types of meristem and where each is found.

3. Which plant tissue stores food?

4. Why is sclerenchyma dead at maturity?

5. What is the function of xylem? Of phloem?

6. Name the tissue that forms the skin's outer layer.

7. Name three kinds of connective tissue.

8. Distinguish voluntary and involuntary muscles with one example each.

9. What is the function of nervous tissue?

10. Why do ligaments need to be strong and slightly flexible?

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