Infection and response

• Malaria is a communicable disease spread by a protist pathogen through mosquitoes
• Ways to stop the spread of malaria

  • Prevent mosquito bites
  • Stop mosquitoes breeding
• Types of Pathogens


  • Bacteria
  • Viruses
  • Protists
  • Fungi
• Bacteria


  • Very small living cells
  • Can produce toxins (poisons) that make you feel ill
• Viruses

  • Much smaller than bacteria
  • Can produce rapidly inside your body
  • Live inside your cells and hijack them to produce more viruses
  • Cell will usually then burst, releasing all the new viruses
• Protists


  • Single-celled eukaryotes
  • Some are parasites that live in or on other organisms and can cause disease
  • Often transmitted to the organism by a vector, which is the thing that carries the protist
• Fungi


  • Come in different shapes
  • Some have a body which is made up of hyphae (thread-like structures)
  • Hyphae can grow and penetrate human skin and the surface of plants, causing disease
  • Hyphae can produce spores, which can be spread to other plants and animals
• Ways Pathogens Can Be Spread


  • Drinking or bathing in dirty water
  • Airborne spread in droplets produced when coughing or sneezing
  • Direct contact by touching contaminated surfaces
• Pathogens can cause disease in both humans and plants
• Viruses can cause cell damage
• Viral Diseases to Know About

  • Measles
  • HIV/AIDS
  • Plant viral diseases
• Measles


  • Spread by droplets from an infected person's coughs and sneezes
  • Causes a red rash and fever
  • Can be very serious, or even fatal, if there are complications
• HIV/AIDS

  • Initially has no symptoms for several years
  • Attacks the immune system (white blood cells)
  • If the immune system is badly damaged, the person can't cope with other infections or cancers
• Plant viral diseases


  • Cause patterns on the leaves of plants
  • Affects the plant's ability to carry out photosynthesis
• Diseases to Know About

  • Measles (viral)
  • Rose black spot (fungal)
  • Malaria (protist)
• Rose black spot


  • Fungus that causes black spots to develop on the leaves of plants
  • Means the plant can't carry out photosynthesis as well, so the plant doesn't grow well
  • Spreads through the environment in water or by the wind
  • Can be treated using fungicides and by removing affected leaves
• Malaria


  • Caused by a protist
  • Part of the protist's life cycle takes place inside the mosquito
  • Mosquitoes pick up the protist when they feed on an infected animal and then infect other animals when they feed
  • Causes episodes of fever and can be fatal
  • Can be reduced by stopping mosquitoes from breeding and using insecticides/mosquito nets
• Bacterial diseases and preventing disease also need to be known
• The human body has a sophisticated defence system to fight pathogens
• Body's Defences Against Pathogens


  • Physical barriers like skin and mucus
  • White blood cells that can attack and destroy pathogens
  • Antibodies that can recognise and bind to specific pathogens
  • Antitoxins that counteract toxins produced by bacteria
• Phagocytosis

  White blood cells consuming and digesting foreign cells and microbes
• Nose and bronchi


  • Have hair-like structures that trap particles that could contain pathogens
• Vaccination can protect against future infections by training the immune system
• Vaccination involves injecting small amounts of dead or weakened pathogens to teach the immune system how to deal with them
• If you have a low lod of white blood cells, you'll be more susceptible to infections
• Phagocytosis


  The process by which a cell engulfs and digests a particle or microorganism