Miss Angus' Biology Class - Plant Tissues

Overview

• Focus on plant tissues: identification, function, and appearance under a microscope.
• Break down into easy study sections for exams.
• Covers Grades 10 to 12 Life Sciences.

Types of Plant Tissues

• Meristematic Tissue: Temporary, involved in growth.
  • Apical Meristems: Found at shoot/root tips, cause primary growth (lengthening).
  • Lateral Meristems: Found in stems, cause secondary growth (thickening).
  • Cambium: Responsible for stem thickness and bark production.
• Permanent Tissue: Includes parenchyma, collenchyma, sclerenchyma, and vascular tissues (xylem and phloem).

Epidermis (Permanent Tissue)

• Function: Protection of underlying tissues.
• Components:
  • Cuticle: Wax layer preventing water loss.
  • Upper/Lower Epidermis: Allows sunlight penetration.
  • Specialized Cells:
    • Stomata (Guard Cells): Control gas exchange.
    • Root Hair Cells: Increase surface area for nutrient absorption.

Ground Tissues

• Parenchyma:
  • Characteristics: Thin cell walls, intercellular airspaces.
  • Functions: Packaging, storage, gaseous exchange, osmosis.
  • Chlorenchyma: Parenchyma with chloroplasts for photosynthesis.
• Collenchyma:
  • Identification: Thickened corners, flexibility.
  • Function: Support and strength in young plants.
• Sclerenchyma:
  • Characteristics: Evenly thickened walls, rigid.
  • Functions: Provides rigidity, found in wood and bark.
  • Types:
    • Fibers: Found in wood.
    • Sclereids: Found in nuts and stone fruits.

Vascular Tissues

• Xylem:
  • Function: Transport water/minerals from roots to shoots.
  • Characteristics: Elongated, dead cells with thick walls.
  • Types:
    • Vessels: Round, end-to-end stacked.
    • Tracheids: Spindle-shaped, overlap.
• Phloem:
  • Function: Transport sugars in two directions.
  • Characteristics: End-to-end stacked, sieve plates, companion cells for support.

Conclusion

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