diseases

• pathogens are microorganisms which cause diseases through water, air and contact
• microorganisms include - bacteria, viruses, fungi and protists
• viral diseases

  measles -> treated by vaccination

  HIV destroys white blood cells and can lead to AIDS

  tobacco mosaic -> yellow leaves so plants cannot photosynthesise
• fungal diseases


  rose black spot -> plants are unable to photosynthesise

  treat it by spraying a fungicide
• protist disease


  malaria spread by vector - mosquitos

  causes fever and/or death

  use nets and insecticide to kill mosqitos
• bacterial disease


  salmonella from food poisoning (vaccinate)

  Gonorrhea STD (protected sex and antibiotics)
• fight diseases by:

  • barriers eg skin, hair, mucus
  • white blood cells -> phagocytes consume them, antibodies, antitoxins
  • vaccinations
• developing drugs - 3 stages.

  1. test on human tissue
  2. test on live animals
  3. test on human volunteers
• testing for new drugs:

  use placebo effect and double blind trials, then peer reviewed
• double blind trial - neither the doctor nor the volunteer know which one is placebo