communicable diseases

• what are the 3 ways to transfer disease?

  Direct contact, water and air
• how is HIV spread?

  sexual contact or exchange of bodily fluids
• what does tobacco mosaic virus cause?

  Mosaic patterns on leaves.
• how does tobacco mosaic virus affect the plant?

  stunts the growth because photosynthesis can't occur
• what's some symptoms of measles?

  fever and red skin rash
• how is aids caused?

  when a person immune system has been badly damaged by HIV
• viruses are tiny non living particles that can reproduce rapidly in the body
• how to viruses reproduce?

  they invade the hosts cells, insert their DNA which is the copied to make more viruses, when the new virus particles have been made they cause the cell to burst releasing the new viruses to invade more cells
• what does the rose black spot do?

  it causes spots on the leaves of rose plants, eventually the leaves discolour and fall off which makes it hard for the plant to photosynthesise
• give an example of a fungal disease?


  rose black spot
• malaria is spread by a female mosquito carrying it, it transfers the infection into the hosts blood stream when it bites them
• how do fungi spread and infect plants?

  they are organisms which have bodies made up of hyphae (thread like structures). the hyphae are able to grow and penetrate tissues but can also produce spores which can spread to animals and plants
• in phyagocytosis the white blood cell finds the pathogen and engulfs it by changing shape
• name 4 non specific defences?

  tears, skin, mucus and stomach acid
• the immune system produces antitoxins which neutralise the toxins produced by the bacteria
• what are the main functions of white blood cells in out immune systems?

  produce antitoxins, antibodies and phagocytosis
• what's a pathogen?


  a microorganism that causes a disease
• what is a anitgen?


  proteins found on the surface of some pathogens with specific shapes that act like signals to allow cell recognition
• what's an antibody?


  protein molecules produced by the white blood cells when recognising pathogens
• when getting a vaccination a dead or inactive pathogen is injected into the blood stream, this causes the body to produce antibodies which fights the pathogen. some of the white blood cells produced stay in the body as memory cells so if the pathogen invades again they can produce antibodies faster and in larger quantities