B3 +B4 infection and disease

• define a pathogen ?

  microorganisms that cause disease
• both plant and animals can be infected by pathogens
• pathogens cause communicable diseases - infectious +easily spread
• 4 types of pathogens ?

  bacteria

  virus

  protists

  fungi
• bacteria are very small living things
• explain why bacteria infections - makes you feel ill ?

  produce toxins that damage cells and tissues
• bacteria reproduces rapidly inside body
• viruses are not cells they are much smaller
• viruses are not cells
• viruses reproduces rapidly inside body

  they live inside cells and replicate themselves using machinary to produce copies

  cell will burst and release all viruses
• describe why viruses make you feel ill ?

  when they reproduce rapidly inside cells - and replicate themselves inside your cells , they make machinery to produce copies causing cells to burst ===== cell damage
• cell damage is why viruses make you feel ill

  after they have reproduced rapidly inside your cells where they live , making copies , causing cells to burst releasing all viruses - cell damage
• protists are single -celled eukaryotic cells
• are protists eukaryotic or prokaryotic cells ?

  euaryotic
• example of a protist ?

  parisites
• where do parisites live ?

  on or inside other organisms and cause damage often transfered by vector
• vector - transfers protists , dont get it themselves
• some fungi are single -celled other have a body - made of hyphae - these grow and penetrate human skin and surface of plants causing disease - the hyphae produce spores
• describe how viruses cause cell damage ?

  live inside cells and replicate themselves using cells machinery to produce copies of themselves = cell burst = releasing viruses
• 3 ways pathogens are spread ?

  • water
  • air
  • direct contact
• describe how water spreads pathogens ?

  some pathogens - picked up by drinking or bathing in dirty water - eg - cholera - bacteria spread by drinking contaminated water
• describe how pathogens are spread by AIR ?

  pathogens carried in air and can be breathed in , carried in droplets produced by coughing or sneezing eg - influenza virus = causes flu
• describe how pathogens are spread by direct contact ?

  pathogens picked up by touching contaminated surfaces including skin eg - athletes foot - fungus , commonly spread by touching things as an infected person
• how to calculate percentage increase ?

  final - initial value divide by initial value x 100
• viral , fungal , protists diseases -
• what disease is measles ?

  viral - spread by droplets from an infected person sneeze/cough

  symptom of measles - red skin rash , fever ,
• measles can be fatal if their are complications eg - pneumonia
• how are peoples protected against measles ?

  vaccinated when young
• HIV - virus spread by sexual contact or exchanging body fluids this can happen by sharing needles
• symptoms of HIV ?

  flu-like symptoms
• how to control HIV ?

  antiretroviral drugs - stop virus replicating , virus attacks immune system
• why is it bad for a person with HIV to get sick ?

  due to immune system being badly damaged it cants cope with other infections or cancers = AIDS
• tobacco mosaic virus is a virus that affects plants , tomatoes
• how do you know if TMV has affected a plant ?

  mosaic pattern on leaves of plant - discoloured meaning plant cant carry out photosynthesis , so virus affects growth
• name 3 viral diseases ?

  • measles
  • HIV
  • tobacco mosaic virus
• name a fungal disease ?

  rose black spot
• what is rose black spot ?

  fungus that causes purple or black spots to develop on leaves of rose plant = leaves turn yellow and drop off
• what does it mean if a plant has been affected by rose black spot fungus ?

  due to leaves turning yellow and drop off = means less photosynthesis can happen = plant doesnt grow well
• how is rose black spot spread ?

  water or wind
• how can people treat rose black spot ?

  1. use fungicides
  2. stripping plants affected leaves - destroying them