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Biology AS AQA

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  1. 1-1-biological-molecules-carbohydrates
    11 主题
  2. 1-2-biological-molecules-lipids
    3 主题
  3. 1-3-biological-molecules-proteins
    5 主题
  4. 1-4-proteins-enzymes
    12 主题
  5. 1-5-nucleic-acids-structure-and-dna-replication
    8 主题
  6. 1-6-atp-water-and-inorganic-ions
    4 主题
  7. 2-1-cell-structure
    7 主题
  8. 2-2-the-microscope-in-cell-studies
    4 主题
  9. 2-3-cell-division-in-eukaryotic-and-prokaryotic-cells
    8 主题
  10. 2-4-cell-membranes-and-transport
    9 主题
  11. 2-5-cell-recognition-and-the-immune-system
    7 主题
  12. 2-6-vaccines-disease-and-monoclonal-antibodies
    6 主题
  13. 3-1-adaptations-for-gas-exchange
    6 主题
  14. 3-2-human-gas-exchange
    14 主题
  15. 3-3-digestion-and-absorption
    5 主题
  16. 3-4-mass-transport-in-animals
    6 主题
  17. 3-5-the-circulatory-system-in-animals
    4 主题
  18. 3-6-mass-transport-in-plants
    6 主题
  19. 4-1-dna-genes-and-chromosomes
    10 主题
  20. 4-2-dna-and-protein-synthesis
    3 主题
  21. 4-3-genetic-diversity-mutations-and-meiosis
    7 主题
  22. 4-4-genetic-diversity-and-adaptation
    6 主题
  23. 4-5-species-and-taxonomy
    4 主题
  24. 4-6-biodiversity
    9 主题
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Exam code:7401

Vaccines

  • Vaccines introduce pathogenic antigens into the body, triggering a specific immune response which results in the release of antibodies by plasma cells

    • Vaccines can contain:

      • weakened forms of the pathogen

      • antigens

      • genetic material that codes for the antigens

  • Vaccinations produce active immunity, as they cause memory cells to be produced

    • The immune system recognises the antigen and triggers a faster, stronger secondary response

    • This response eliminates the pathogen before symptoms develop

Graph showing measles antibodies in blood over time. Peaks after vaccination, decreases, then spikes higher after infection. Labeled "Vaccination" and "Infection."
The measles vaccine introduces measles antigens to the body, initiating the production of antibodies; subsequent exposure to a measles infection will result in a faster, stronger secondary response

Herd Immunity

  • Vaccines protect individuals and populations from disease by triggering immunity

  • Herd immunity occurs when enough people are vaccinated to stop the spread of infection

  • This protects unvaccinated individuals, such as babies or those with weakened immune systems

  • The more infectious a disease is, the higher the proportion of the population that must be vaccinated

  • If vaccination rates drop below the threshold, herd immunity is lost (e.g. measles outbreak in Swansea, Wales, 2012)

Diagram showing disease spread: no vaccination results in full spread, some vaccination limits spread, most vaccination contains disease.
Herd immunity reduces the number of susceptible individuals in a population and halts the spread of infection

Examiner Tips and Tricks

Remember vaccines trigger the primary immune response, during which T helper cells trigger plasma cells to secrete specific antibodies. This leads to the production of memory cells which will give a faster and stronger secondary response.

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