biology - infection and response.

• Bacteria


  Produce toxins that damage tissues and make us feel ill
• How bacteria and viruses spread (in the body)


  1. Bacteria reproduce rapidly inside the body

  2. Viruses live and reproduce inside cells, causing cell damage
• HIV


  • Causes a life-threatening illness
  • Spread by sexual contact and sharing needles
  • Can be prevented by antiretroviral drugs
  • AIDS - body can no longer deal with infection and cancers
• Rose Black Spot


  • Fungal disease
  • Black/purple spots develop on leaves, that turn yellow and drop early
  • Affects plant growth as photosynthesis is reduced
  • Spread by water and wind
  • Controlled by destroying leaves and using fungicides
• How vaccines work?


  1. Introduce a dead/inactive form of pathogen into the body

  2. WBC stimulated to produce antibodies against pathogen

  3. WBC divides by mitosis, producing many copies of itself

  4. If pathogen re-enters the body, WBC can make antibodies quickly preventing infection