B3 - Infection and Response

• What are pathogens?

  Microorganisms that cause infectious disease
• How do pathogens spread?

  Through direct contact, water, or air
• What are the characteristics of viruses?

  • Very small
  • Enter cells and replicate using the cell's biochemistry
  • Cause cell damage leading to illness
• What are the four types of pathogens?

  Viruses, bacteria, protists, and fungi
• What are the characteristics of bacteria?

  • Small
  • Multiply quickly through binary fission
  • Produce toxins that can damage cells
• What are the characteristics of protists?

  • Some are parasitic
  • Use humans and animals as hosts
  • Cause damage to the host
• What are the characteristics of fungi?

  • Can be single-celled or multicellular with hyphae
  • Produce spores that can spread to other organisms
• How can pathogens be spread through direct contact?

  By touching contaminated surfaces
• What is droplet infection?

  Pathogens expelled in droplets from sneezing, coughing, or talking
• What are the methods to limit the spread of pathogens?

  • Improving hygiene (hand washing, disinfectants)
  • Reducing contact with infected individuals
  • Removing vectors (pesticides, habitat removal)
  • Vaccination
• What is the purpose of vaccination?

  To make an individual immune to a disease
• What are the symptoms of measles?

  Fever and red skin rash
• How is measles spread?

  Through droplet infection
• What are the symptoms of HIV?

  Initially flu-like symptoms, leading to AIDS
• How is HIV spread?

  By sexual contact or exchange of bodily fluids
• How can the spread of HIV be prevented?

  • Using condoms
  • Not sharing needles
  • Screening blood for transfusions
  • Bottle-feeding for mothers with HIV
• What are the symptoms of tobacco mosaic virus?

  Discolouration of leaves, reducing yield
• How is tobacco mosaic virus spread?

  Contact between diseased and healthy plants, insects as vectors
• What are the symptoms of salmonella food poisoning?

  • Fever
  • Stomach cramps
  • Vomiting
  • Diarrhoea
• How is salmonella spread?

  Through raw meat and eggs, unhygienic conditions
• How can salmonella be prevented?

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

  • Thick yellow or green discharge
  • Pain when urinating
• How is gonorrhoea spread?

  Through unprotected sexual contact
• How can gonorrhoea be prevented?

  • Using contraception (condoms)
  • Antibiotics for treatment
• What are the symptoms of rose black spot?

  • Purple or black spots on leaves
  • Leaves turn yellow and drop early
• How is rose black spot spread?

  By water (rain) or wind
• How can rose black spot be prevented?

  • Using fungicides
  • Stripping affected leaves (burning them)
• What are the symptoms of malaria?

  • Fevers
  • Shaking
• How is malaria spread?

  By the female Anopheles mosquito
• How can malaria be prevented?

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

  • Skin: physical barrier, antimicrobial secretions
  • Nose: hairs and mucus
  • Trachea and bronchi: mucus and cilia
  • Stomach: hydrochloric acid
• What are the modes of action of the specific immune system?

  • Phagocytosis: engulfs and destroys pathogens
  • Producing antibodies: bind to antigens, clumping pathogens
  • Producing antitoxins: neutralise toxins
• What is herd immunity?

  Immunity in a large proportion of the population reducing pathogen spread
• What does a vaccine contain?

  A dead or inactivated form of the pathogen
• What are the advantages of vaccination?

  • Eradicated many diseases (e.g., smallpox)
  • Prevents epidemics through herd immunity
• What are antibiotics?

  Medicines that kill bacterial pathogens without harming body cells
• Why can't antibiotics kill viruses?

  Because viruses use body cells to reproduce
• What is an example of an antibiotic?

  Penicillin
• What is the concern regarding bacteria and antibiotics?

  • Bacteria are becoming resistant to antibiotics
  • Mutations lead to non-resistant bacteria surviving and reproducing
• How can the development of antibiotic-resistant strains be prevented?

  • Stop overusing antibiotics
  • Finish courses of antibiotics