Chapter-Tissues in Action Science Exploration class 9 in english Medium CBSE Notes

Chapter 3. Tissues in Action

This section explains permanent tissues found in plants. After completing growth, meristematic cells undergo differentiation and become permanent tissues. These tissues perform specialised functions such as storage, photosynthesis, protection and transportation.

8. Permanent Tissue

Meristematic cells divide continuously, but after a certain stage they lose the ability to divide and become specialised. These specialised tissues are known as permanent tissues.

Definition

Permanent tissue is a tissue formed from meristematic tissue after differentiation. Its cells lose the power of division and perform specific functions.

Characteristics

• Mature Cells – Cells are fully developed.
• No Cell Division – Cells generally do not divide.
• Large Vacuoles – Vacuoles are well developed.
• Specialised Functions – Each tissue performs a particular function.

Classification of Permanent Tissue

• Simple Permanent Tissue – Made up of only one type of cells.
• Complex Permanent Tissue – Made up of more than one type of cells working together.

9. Simple Permanent Tissue

Simple permanent tissues consist of similar cells performing the same function. They mainly provide storage, support and protection to plants.

Types of Simple Permanent Tissue

• Parenchyma
• Collenchyma
• Sclerenchyma

10. Parenchyma

Parenchyma is the most common living tissue in plants. It is found in leaves, stems, roots and fruits. These cells mainly store food and water.

Definition

Parenchyma is a simple permanent living tissue made up of thin-walled cells.

Characteristics

• Living Cells – Cells remain alive.
• Thin Cell Wall – Made of cellulose.
• Large Vacuole – Stores water and nutrients.
• Intercellular Spaces – Spaces are present between neighbouring cells.

Functions

• Storage – Stores food and water.
• Photosynthesis – Chlorenchyma contains chlorophyll and prepares food.
• Buoyancy – Aerenchyma helps aquatic plants float.
• Healing – Helps repair injured plant parts.

Types of Parenchyma

• Chlorenchyma – Contains chlorophyll and performs photosynthesis.
• Aerenchyma – Contains large air spaces that help aquatic plants float.

11. Collenchyma

Collenchyma provides flexibility and mechanical support to young stems and leaves. It allows plants to bend without breaking.

Definition

Collenchyma is a simple permanent living tissue that provides mechanical support and flexibility.

Characteristics

• Living Cells – Cells remain alive.
• Unevenly Thickened Walls – Cell corners are thickened.
• Flexible Tissue – Allows bending without breaking.
• Little Intercellular Space – Cells remain closely packed.

Functions

• Mechanical Support – Supports growing plant parts.
• Flexibility – Prevents stems and leaves from breaking.
• Protection – Strengthens young tissues.

12. Sclerenchyma

Sclerenchyma is a dead tissue that provides maximum strength and rigidity to mature plant parts.

Definition

Sclerenchyma is a simple permanent dead tissue with thick, lignified cell walls.

Characteristics

• Dead Cells – Cells lose their living contents at maturity.
• Very Thick Walls – Cell walls contain lignin.
• No Intercellular Spaces – Cells remain tightly packed.
• Hard Tissue – Provides great mechanical strength.

Functions

• Mechanical Strength – Makes plant parts hard and strong.
• Protection – Protects seeds and fruits.
• Support – Helps plants remain upright.

13. Comparison of Simple Permanent Tissues

Feature	Parenchyma	Collenchyma	Sclerenchyma
Nature	Living	Living	Dead
Cell Wall	Thin	Unevenly Thickened	Very Thick and Lignified
Intercellular Space	Present	Very Little	Absent
Main Function	Storage	Support & Flexibility	Strength & Protection
Example	Fruit Pulp	Leaf Stalk	Coconut Husk

14. ATP Education Concept Builder

Easy Memory Trick

• Parenchyma → Packing & Storage Tissue.
• Collenchyma → Flexible Support Tissue.
• Sclerenchyma → Strong Mechanical Tissue.

ATP Education Tip

CBSE frequently asks students to compare Parenchyma, Collenchyma and Sclerenchyma. Remember that Parenchyma stores food, Collenchyma provides flexibility, and Sclerenchyma provides maximum strength. This comparison is important for objective, competency-based and descriptive questions.

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