diseases and viruses

• what is a pathogen?
• what is a pathogen?


  a microorganism that causes infectious disease
• microorganisms that can be pathogens

  • bacteria
  • viruses
  • protists
  • fungi
• how can bacteria make people feel ill?

  produces toxins that damages tissues
• how can viruses damage cells?

  they replicate inside the cells, they burst open, damaging the cells
• give four ways that pathogens can be spread

  • direct contact
  • in water
  • in the air
  • by vectors
• what are disease vectors?

  organisms that carry pathogens and pass them on to other organisms
• give four ways of reducing or preventing the spread of disease

  • isolating infected people
  • vaccinating against disease
  • destroying vectors
  • following simple hygiene measures
• what type of microorganism causes measles?


  virus
• give two symptoms of measles

  • red skin rash
  • fever
• how is measles spread?

  sneezes and coughs from infected people
• why are most young people vaccinated against measles?


  measles is a serious disease that can have fatal complications
• what type of microorganism is HIV?

  virus
• how is HIV spread?

  exchange of certain bodily fluids
• what does HIV do to the body?


  HIV attacks the bodys immune cells
• what are the initial symptoms of HIV infection?


  flu-like symptoms
• how can HIV be controlled?

  with antiretroviral drugs
• describe late stage HIV infection

  the immune system has been so badly damaged so it cant fight off other infections
• what organisms are affected by tobacco mosaic virus?


  plants
• describe what happens to plants infected with tobacco mosaic virus

  get a discoloured pattern on their leaves giving them less chlorophyll which means the plant photosynthesises less.
• what type of microorganism is salmonella?


  a bacteria that causes food poisoning
• give four symptoms of salmonella food poisoning

  • fever
  • vomiting
  • diarrhoea
  • abdominal cramps
• give two ways that people can become infected with salmonella

  • eating food that came from an animal infected with salmonella
  • eating food that was prepared in unhygienic conditions
• how is the spread of salmonella being controlled in the UK?

  some poultry is vaccinated against salmonella to control the spread
• what type of microorganism causes gonorrhoea?

  bacteria
• give two symptoms of gonorrhoea

  • pain when urinating
  • thick yellow or green discharge from the vagina or penis
• how is gonorrhoea spread?


  spread by sexual contact
• give two ways of controlling the spread of gonorrhoea

  • using methods of contraception like condoms
  • treating infected people with antibiotics
• why has it become harder to treat gonorrhoea infections with penicillin?

  there are now many strains of gonorrhoea that are resistant to penicillin