the spread of diseases

• one virus example: measles

  • it is spread by inhalation of droplets produced by infected people when coughing or sneezing.
  • symptoms include a fever, red skin rash and it can be fatal
• viruses


  they live and reproduce rapidly inside an organism's cells. this can damage or destroy the cell.
• Bacteria


  reproduces rapidly inside organisms and may produce toxins that damage tissues and cause illness
• one example of a bacteria: salmonella

  • it is spread by in food that is being indigested
  • symptoms include fever, abdominal cramps, vomiting and diarrhoea
• controlling the spread of diseases

  • hygiene
  • isolation
  • controlling vectors
  • vaccination
• one example of fungi: rose black spot

  • it is spread by water and wind
  • symptoms include purple or black spots on the leaves and reduces plant's ability to photosynthesis, affecting growth.
• one example of a protist: malaria

  • spread by mosquitos feed on blood of infected people and spread to other person by feeding on them. (vectors)
  • symptoms include: episodes of fever and it can be fatal
• detection of plant diseases

  • stunted growth
  • spots on leaves
  • areas of rot or decay
  • growths
  • malformed stems or leaves
  • discolouration
  • pest infestation
• identifying plant diseases

  • gardening manuals
  • laboratory testing of infected plants
  • testing kits
• Aphids


  they are insects that suck sap from the stems of plants. this results in: reduced rate of growth, wilting and discolouration of leaves
• physical barriers


  cellulose walls

  tough waxy cuticle

  bark on trees
• chemical barriers


  many plants produces antibacterial chemicals

  poison production stops animals eating plants
• mechanical barriers


  thorn and hairs stop animals eating the plant

  leaves that curl or droop when touched

  some plants mimic the appearance of unhealthy or poisonous plants.