Class 9th Science Tissues Notes


Introduction

🔬 A tissue is a group of similar cells performing a specific function.
🌿 In plants, tissues provide support & transport.
🦁 In animals, tissues perform movement, protection, and coordination.

Tissues are broadly classified into:
✔️ Plant Tissues 🌱
✔️ Animal Tissues 🦠


Plant Tissues

1. Meristematic Tissues (Growth Tissues)

📌 These tissues have actively dividing cells found in growing regions of plants.

🔬 Types of Meristematic Tissues:
🌱 Apical Meristem – Found at the tips of roots & shoots, helps in length growth.
🌱 Lateral Meristem – Found in stem & root sides, helps in thickness growth.
🌱 Intercalary Meristem – Found at nodes (grass, bamboo), helps in regrowth.


2. Permanent Tissues (Non-Dividing Tissues)

📌 Formed from meristematic tissues, these do not divide and perform specific functions.

A. Simple Permanent Tissues

📌 Made of only one type of cell.

🔹 Parenchyma – Living cells, stores food & provides support (e.g., in potatoes).
🔹 Collenchyma – Provides flexibility & mechanical support (e.g., in celery stems).
🔹 SclerenchymaDead cells with thick walls, provide strength (e.g., coconut husk).


B. Complex Permanent Tissues

📌 Made of more than one type of cell and help in transport.

🌿 Xylem (Water-Conducting Tissue)
💧 Transports water & minerals from roots to leaves.
💧 Components:
✔️ Tracheids & Vessels – Conduct water.
✔️ Xylem Parenchyma – Stores food.
✔️ Xylem Fibres – Provides support.

🌿 Phloem (Food-Conducting Tissue)
🍏 Transports food (sugar) from leaves to other plant parts.
🍏 Components:
✔️ Sieve Tubes & Companion Cells – Conduct food.
✔️ Phloem Parenchyma & Fibres – Provide support.


Animal Tissues

1. Epithelial Tissue (Covering & Protective Tissue)

📌 Covers body surfaces, organs, and cavities.

🔹 Types of Epithelial Tissue:
✔️ Squamous Epithelium – Flat, thin cells (e.g., lining of lungs).
✔️ Cuboidal Epithelium – Cube-shaped cells (e.g., kidney tubules).
✔️ Columnar Epithelium – Tall, column-like cells (e.g., intestine lining).
✔️ Ciliated Epithelium – Has hair-like cilia (e.g., respiratory tract).


2. Connective Tissue (Binding & Support Tissue)

📌 Connects and supports organs & tissues.

🔹 Types of Connective Tissue:
✔️ Bone – Hard, provides support.
✔️ Cartilage – Flexible, present in nose, ears.
✔️ Ligaments – Connect bone to bone (elastic).
✔️ Tendons – Connect muscle to bone (strong & tough).
✔️ Areolar Tissue – Found between skin & muscles.
✔️ Blood – Fluid tissue transporting oxygen & nutrients.


3. Muscular Tissue (Movement Tissue)

📌 Helps in body movement & posture.

🔹 Types of Muscular Tissue:
✔️ Striated (Skeletal) MuscleVoluntary, moves bones (e.g., hand, legs).
✔️ Smooth (Unstriated) MuscleInvoluntary, found in internal organs.
✔️ Cardiac MuscleInvoluntary, found in the heart, never fatigues.


4. Nervous Tissue (Coordination & Control Tissue)

📌 Forms the brain, spinal cord, and nerves.

🔬 Made up of neurons, which transmit electrical impulses.
Parts of a Neuron:
✔️ Dendrites – Receive signals.
✔️ Axon – Sends signals.
✔️ Cell Body – Controls neuron activity.


Differences Between Plant & Animal Tissues

✔️ Plant Tissues 🌿

  • Have cell walls.
  • Fixed shape.
  • Support provided by xylem & sclerenchyma.
  • Grow in specific regions.

✔️ Animal Tissues 🦁

  • No cell walls.
  • Can change shape.
  • Support provided by bone & cartilage.
  • Growth occurs throughout the body.

Conclusion

✔️ Tissues help in specialization, making organisms more efficient.
✔️ Plants have supporting & transporting tissues.
✔️ Animals have tissues for movement, coordination, and protection.


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