Infection and response

• What are pathogens?

  Microorganisms that cause infectious disease, including viruses, bacteria, protists, and fungi.
• How do pathogens spread?

  They can spread through direct contact, by water, or by air.
• What is a characteristic of viruses?


  They are very small and can replicate inside host cells.
• What happens when a virus replicates inside a cell?

  The cell bursts, releasing copies of the virus into the bloodstream.
• What is the effect of viral damage on the host?


  It makes the individual feel ill due to cell damage and destruction.
• How do bacteria reproduce?

  They multiply quickly through a process called binary fission.
• What do bacteria produce that can harm cells?


  Toxins that can damage cells.
• What is a characteristic of protists?


  Some are parasitic and use humans and animals as hosts.
• What are fungi composed of?

  They can be single-celled or have a body made of hyphae.
• How do fungi spread?

  They produce spores that can be spread to other organisms.
• What are the main ways communicable diseases are spread?

  • Direct contact (e.g., kissing, touching contaminated surfaces)
  • By water (e.g., drinking dirty water)
  • By air (e.g., droplet infection from sneezing or coughing)
• What measures can reduce the spread of diseases?

  • Improving hygiene (hand washing, disinfectants)
  • Reducing contact with infected individuals
  • Removing vectors (using pesticides)
  • Vaccination (injecting harmless pathogens)
• Why are viruses particularly dangerous?

  They can enter all types of cells, and there are no medicines to cure them.
• What are the symptoms of measles?

  Fever and red skin rash, which can lead to pneumonia, encephalitis, and blindness.
• How is measles spread?

  Through droplet infection.
• How is measles prevented?

  By vaccinations for young children.
• What are the initial symptoms of HIV?

  Flu-like symptoms.
• How does HIV affect the immune system?


  It attacks the immune system and can lead to AIDS.
• How is HIV spread?

  By sexual contact or exchange of bodily fluids such as blood.
• What are the prevention methods for HIV?

  • Using condoms
  • Not sharing needles
  • Screening blood for transfusions
  • Bottle-feeding children of HIV-positive mothers
  • Using antiretroviral drugs
• What are the symptoms of tobacco mosaic virus in plants?

  Discolouration of the leaves, reducing photosynthesis and yield.
• How is tobacco mosaic virus spread?

  Through contact between diseased and healthy plants, and by insects as vectors.
• How is tobacco mosaic virus prevented?

  By good field hygiene and pest control, and growing resistant strains.
• What is a common bacterial disease that is on the rise?


  Salmonella food poisoning.
• What are the symptoms of Salmonella food poisoning?

  Fever, stomach cramps, vomiting, and diarrhoea.
• How is Salmonella spread?

  Through raw meat and eggs, and unhygienic conditions.
• What are the prevention methods for Salmonella food poisoning?


  • Vaccinating poultry against Salmonella
  • Keeping raw meat away from cooked food
  • Washing hands and surfaces when handling food
  • Cooking food thoroughly
• What are the symptoms of gonorrhoea?

  Thick yellow or green discharge and pain when urinating.
• How is gonorrhoea spread?

  Through unprotected sexual contact.
• How is gonorrhoea prevented?

  By using contraception such as condoms and antibiotics.
• What are the symptoms of rose black spot?

  Purple or black spots on leaves, yellowing leaves, and early leaf drop.
• How is rose black spot spread?

  By water (rain) or wind.
• How is rose black spot prevented?

  By using fungicides or stripping affected leaves.
• What are the symptoms of malaria?


  Fevers and shaking.
• How is malaria spread?

  By the female Anopheles mosquito, which acts as a vector.
• What are the prevention methods for malaria?


  • Using insecticide-coated nets
  • Removing stagnant water
  • Taking antimalarial drugs
• What is the role of the non-specific defence system?

  To prevent pathogens from entering the body.
• What is the function of the skin in the immune system?

  Acts as a physical barrier and produces antimicrobial secretions.
• How does the nose help in the immune response?

  It has hairs and mucus that prevent particles from entering the lungs.
• What is the role of the trachea and bronchi in the immune system?

  They secrete mucus to trap pathogens and have cilia to waft mucus upwards.