Mod 7 - exam

• Pathogen - Organism capable of causing disease
• Bacteria - prokaryotic + unicellular + no membrane bound organelles - Tuberculosis
• Virus - Protein coated + non-cellular + RNA & DNA - Influenza
• Fungi - Unicellular + Eukaryotic + cell membrane & organelles - Athletes foot
• Protozoa - Unicellular + eukaryotic + cell membrane & organelles - Amoeba
• Prion - Misfolded protein + abnormal + non-cellular - Kuru
• Macro parasite - Macroscopic + multicellular + eukaryotic - Tapeworms
• Macro parasite types - Helminths (worms) + Arthropods (segmented body)
• Fungi plant symptoms - Leaf rust + wood rot + mildew

  Transmission - Spores contaminate soil + equipment - Enter stomatal pores + damages xylem & phloem
• Bacteria plant symptoms - Blight + wilts + Leaf spots

  Transmission - Bacterial reservoirs in soil + weeds + seeds - Contaminated equipment
• Virus plant symptoms - Yellowing of leaves + Mosaic + streaking patterns

  Transmission - Viral reservoirs on contaminated equipment + frequent handling
• Direct contact - Physical contact between an infected and non-infected organism - Touching + Sexual contact
• Indirect contact - No human-to-human contact, transmitted through contaminated surfaces + objects + vectors - Cough & sneeze droplets + Contaminated food + water
• Vector - Organism that transfers disease - Mosquito carrying malaria
• For disease present in agriculture

  • Pathogen must be present
  • Immunocompromised host
  • Favourable environment
• Factors contributing to disease spread

  • Loss of genetic diversity
  • Intensive farming
  • Border control
  • Antibiotic + pesticide resistance
• Loss of genetic diversity

  • Cloning in farming decreased genetic diversity
  • Causing crops in danger of being wiped out by disease
  • Example - Irish potato famine
• Intensive farming

  • Increases chance of pathogen transmission
  • Intensive farming practices packed animals and crops close together
• Border control

  • Plants carry diseases when coming to Australia
  • Australia's natural wildlife are susceptible to new disease from outside of Australia
  • Border control is strict to prevent diseases from other countries
• Passive plant defence - Barriers preventing pathogen to enter

  Physical barriers - Bark + cell wall + stomata + vertical hanging leaves
• Active plant defence - Defences that unleash once pathogen has entered plant

  Defences - Toxins + cell wall + Apoptosis
• Eucalyptus Tree

  • Cell wall amplification - cell wall thickens, prevents pathogen entering
  • Toxins - plant emits toxins to kill pathogens
  • Hypersensitivity - Infected cells die, prevent pathogens spreading
• Fungus Puccinia Psidii

  Cause - Fungus causes eucalyptus rust

  Transmission - Pathogen enters through roots of plant + Attack plant cells - Causing discolouration + stunted growth
• Pasteur developed germ theory of disease and vaccines
• Pasteur disproved the spontaneous generation theory
• Pasteur proved that microbes could not spontaneously generate, but had to be grown
• Koch proves that microbes cause disease
• Koch developed agar plate technique for culturing
• Adaptation of pathogen that facilitates entry into host - bacterium Helicobacter pylori causes stomach ulcers in humans. It has a flagellum that allows it to move and penetrate the mucus lining/barrier of the stomach wall.
• Way pathogen can pass from person to person - direct and indirect such as cough droplets in air or touching
• Koch's postulates -

  1. Pathogen must be present
  2. Pathogen must be able to be isolated and grown
  3. Healthy host must develop same symptoms as original host
  4. pathogen must be re-isolated
• Koch discovered, isolated and grew the bacteria responsible for causing anthrax
• Pasteur - microbial fermentation theory + pasteurisation
• Pasteur developed vaccines for chicken cholera + anthrax + rabies