B3: Infection and response

• What are pathogens?

  Microorganisms that cause infectious disease
• How can pathogens be spread?

  By direct contact, water, or air
• How do bacteria and viruses reproduce inside the body?

  They reproduce rapidly
• What do bacteria produce that can make us feel ill?

  Toxins that damage tissues
• Where do viruses live and reproduce?

  Inside cells, causing cell damage
• What are the six key ways disease is transmitted?

  • In the air
  • By direct contact
  • By animals
  • By bodily fluids
  • Water or food
  • Mosquitoes or insects
• What are the symptoms of measles?

  Fever and a red skin rash
• Why is measles considered a serious illness?

  It can be fatal if complications arise
• Who is most commonly vaccinated against measles?

  Most young children
• How is the measles virus spread?

  By inhalation of droplets from sneezes
• What initial illness does HIV cause?

  A flu-like illness
• What happens if HIV is not controlled?

  It attacks the body’s immune cells
• What occurs during late-stage HIV infection, or AIDS?

  The immune system is severely damaged
• How is HIV spread?

  By sexual contact or body fluid exchange
• What is tobacco mosaic virus (TMV)?

  A widespread plant pathogen
• What symptom does TMV cause in plants?

  A mosaic pattern of discolouration
• How is TMV spread?

  Via mechanical wounds from contaminated tools
• How is Salmonella food poisoning spread?

  By bacteria ingested in food
• What symptoms are caused by Salmonella?

  Fever, abdominal cramps, vomiting, diarrhoea
• How does the UK control the spread of Salmonella?

  Poultry are vaccinated against Salmonella
• What are the symptoms of gonorrhoea?

  Thick yellow or green discharge and pain
• What causes gonorrhoea?

  A bacterium
• How was gonorrhoea treated in the past?

  With the antibiotic penicillin
• How is gonorrhoea spread?

  By sexual contact
• How can the spread of gonorrhoea be controlled?

  By treatment with antibiotics
• What is rose black spot?

  A fungal disease affecting plants
• What symptoms does rose black spot cause?

  Purple or black spots on leaves
• How is rose black spot spread?

  By water or wind
• What pathogens cause malaria?

  Protists
• How can rose black spot be treated?

  Using fungicides and removing affected leaves
• What is the life cycle of the malarial protist?

  It includes the mosquito
• What are the symptoms of malaria?

  Recurrent episodes of fever
• How is the spread of malaria controlled?

  By preventing mosquito breeding and using nets
• What are the non-specific defence systems against pathogens in humans?

  • Skin forms a protective layer
  • Mucus and hair in the nose trap pathogens
  • Mucus and cilia in the trachea trap pathogens
  • Hydrochloric acid in the stomach kills pathogens
• What is the role of the skin in pathogen defense?

  It forms a protective layer covering the body
• How does mucus in the nose help protect against pathogens?

  It traps pathogens before they enter the lungs
• What happens when the nose is blown?

  Mucus is removed with trapped pathogens
• What do goblet cells secrete?

  Mucus that traps pathogens
• How do cilia help protect the lungs?

  They beat mucus away from the lungs
• What does hydrochloric acid in the stomach do?

  It destroys microorganisms swallowed with food