2.4 Kingdom Classification: Fungi

Characteristics of Kingdom Fungi

  • Eukaryotic: Possess a true nucleus and membrane-bound organelles.
  • Heterotrophic: Obtain nutrients by absorbing dissolved organic molecules (saprophytic or parasitic).
  • Cell Wall: Made of chitin.
  • Reproduction: By spores, budding, or fragmentation.
  • Structure: Most are multicellular (hyphae forming mycelium); yeasts are unicellular.

Basic Structure of Mould

  • Hyphae: Thread-like structures forming the fungal body.
  • Mycelium: Entire mass of hyphae.
  • Sporangiophores: Specialized hyphae bearing sporangia.
  • Sporangium: Sac-like structure containing spores.
  • Spores: Reproductive units.

Nutrition and Respiration in Mould

  • Nutrition: Primarily saprophytic (from dead/decaying matter); secrete enzymes to break down food externally, then absorb.
  • Respiration:
    • Aerobic: In presence of oxygen, complete glucose breakdown.
    • Anaerobic (Fermentation): In absence of oxygen, incomplete glucose breakdown (e.g., alcohol in yeast).

Useful Fungi (Applications)

  • Food Production:
    • Yeast: Baking (leavening), brewing (alcohol).
    • Mushrooms: Edible food source.
    • Cheese Production: Ripening and flavor development (e.g., Roquefort, Camembert).
  • Medicine:
    • Antibiotics: Penicillin (Penicillium chrysogenum).
    • Immunosuppressants: Cyclosporine.
  • Decomposition: Break down dead organic matter, recycle nutrients.

Harmful Fungi (Applications)

  • Diseases:
    • In Plants: Rusts, smuts, blights (crop loss).
    • In Humans: Skin infections (ringworm, athlete's foot), candidiasis, respiratory infections.
  • Food Spoilage: Cause spoilage of food items (bread, fruits), producing toxins (e.g., aflatoxins by Aspergillus).
  • Damage to Materials: Grow on and damage wood, textiles, etc.