The Bio Brief

 What are Plant Tissues?

Plant tissues are groups of similar cells that work together to perform specific functions like growth, support, transport, and protection.

 Classification of Plant Tissues

Plant Tissues

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Meristematic       Permanent

(Growing)          (Non-growing)

1. MERISTEMATIC TISSUE (Growing Tissue)

 Function:

Helps in growth of plants

 Location:

Only at special regions

Features:

• Cells actively divide
• Dense cytoplasm
• Thin cell walls
• Large nucleus
• No vacuole (because cells are busy dividing)

 Types of Meristematic Tissue

Meristematic Tissue

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Apical     Lateral        Intercalary

 Apical Meristem

• Found at tips of roots & stems
• Increases length

 Lateral Meristem (Cambium)

• Found on sides of stem/root
• Increases girth (thickness)

 Intercalary Meristem

• Found near nodes (in grasses)
• Helps in regrowth

2. PERMANENT TISSUE

 Formed from meristematic cells

 Cells lose power of division

 Process called Differentiation

 Permanent Tissue Types

Permanent Tissue

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Simple              Complex

A. SIMPLE PERMANENT TISSUE

Made of one type of cells

Types:

1. Parenchyma

• Living cells
• Thin walls
• Large spaces between cells
• Stores food

Special types:

• Chlorenchyma → contains chlorophyll → photosynthesis
• Aerenchyma → air spaces → helps aquatic plants float

2.Collenchyma

• Living cells
• Provides flexibility
• Allows bending without breaking
• Found in leaf stalks

3. Sclerenchyma

• Dead cells
• Thick walls (lignin)
• Makes plant hard & strong
• Example: coconut husk

 Epidermis (Protective Tissue)

Outermost layer

Protects plant

Prevents water loss

Features:

• Single layer of cells
• No intercellular spaces
• Covered with waxy cuticle

 Stomata

Small pores on leaves:

Stomata

   ↓

Gas exchange

Transpiration

Surrounded by guard cells

 Root Hairs

• Absorb water
• Increase surface area

Desert Plants

• Thick waxy cutin
• Reduces water loss

 Cork (in old plants)

• Dead cells
• Contains suberin
• Prevents gas & water entry

 B. COMPLEX PERMANENT TISSUE

Made of different types of cells working together

Two types:

Complex Tissue

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Xylem     Phloem

Together they form vascular bundle

 XYLEM (Water Transport)

Carries water & minerals upward.

Parts:

• Tracheids
• Vessels
• Xylem parenchyma
• Xylem fibres

Functions:

• Transport water
• Provide support

(Most xylem cells are dead)

PHLOEM (Food Transport)

Carries food from leaves to rest of plant.

Parts:

• Sieve tubes
• Companion cells
• Phloem parenchyma
• Phloem fibres

(Only fibres are dead)

Revision Chart

Meristematic → Growth

Parenchyma → Storage

Collenchyma → Flexibility

Sclerenchyma → Strength

Xylem → Water transport

Phloem → Food transport

Epidermis → Protection