Fungi

• Fungi


  Eukaryotic organisms with membrane-enclosed nuclei and organelles
• Fungi


  • Rhizopus
  • Yeast
  • Mushrooms
• Cell walls of fungi

  Made of chitin, a tough carbohydrate
• Nutrition of fungi


  • They are all heterotrophic (cannot make own food)
  • Either parasitic or saprophytic
• Parasitic fungi


  • Obligate parasites only take food from a live host and require a host to reproduce
  • Facultative parasites can get food from live or dead host
• Saprophytic fungi


  • Decomposers
  • Found in soil, dead animals and rotting leaves
  • Act as decomposers, vital for the environment
• Edible and poisonous fungi

  • Edible: truffles, field mushrooms
  • Poisonous: death cap, destroying angel
• Main characteristics of fungi

  • Reproduce by means of spores
  • Lack chlorophyll and are heterotrophic
  • Do not ingest food but secrete enzymes and absorb nutrients through rhizoids
  • Have cell walls made of chitin
  • Body made of hyphae which join to form mycelium

  
• Difference between a bacteria and a fungus

  Not specified

  
• Difference between a fungi cell and a plant cell


  Not specified

  
• Common Bread Mould (Rhizopus)

  • Nutrition: Saprophyte of starchy foods, secretes enzymes and absorbs nutrients
  • Structure: Tubes called hyphae form a mycelium, has a stolon (aerial hypha) to spread quickly, is a multicellular fungus

  
• Life cycle of Rhizopus

  1. Asexual reproduction: Sporulation - hyphae grow sporangiophores, sporangia form spores

  2. Sexual reproduction: Hyphae from plus and minus strains meet, form gametangia, zygote produced, zygospore forms, germinates to produce haploid hypha

  
• Yeast


  Single-celled/unicellular fungi, also called Saccharomyces, have thin chitin walls and food storage vacuoles

  
• Yeast respiration


  Respires anaerobically, breaks down glucose to produce ethanol and carbon dioxide
• Habitats of yeast


  • Carbohydrate
  • Leaf surfaces
  • Fruits
  • Flowers
• Yeast reproduction


  Asexual by budding - parent cell divides by mitosis, new cell forms
• Economic importance of fungi

  • Advantages: Yeast used to produce alcohol, mushrooms as food source
  • Disadvantages: Destroy food, crops, materials, cause diseases
• Sterile and aseptic techniques

  • Asepsis: Free of pathogens, using disinfectant, keeping containers closed
  • Sterile: Free of all microorganisms, using high temperature, flaming equipment
• Experiment to investigate growth of leaf yeast using agar plates


  1. Wash hands, disinfect surfaces, sterilise equipment, place leaf on agar, incubate, set up control

  2. Reasons: Remove microorganisms, prevent contamination, allow optimal growth conditions, ensure no external microorganisms enter
• Results: Positive - pink yeast colonies, Negative - no colonies due to high pollution
• Disposal of grown microorganisms: Soak in disinfectant or sterilise in autoclave