3.10 Vaccination
6 exam questions worth 12 marks. Write your answer, open the mark scheme, then give yourself the marks you earned. Your answers are saved on this device.
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What does a vaccine contain?
Mark scheme
dead / inactive / weakened form of a pathogen / antigens (of a pathogen)
Model answer
A vaccine contains a small amount of a dead or inactive form of a pathogen.
Explain how vaccination protects a person against measles.
Mark scheme
- vaccine contains dead / inactive measles virus / its antigens (1)
- lymphocytes produce antibodies (against the antigens) (1)
- memory cells / memory lymphocytes are produced (1)
- on later infection, antibodies are made quickly / in large amounts so the virus is destroyed before symptoms (1)
Model answer
The vaccine contains inactive measles virus with its antigens. These stimulate lymphocytes to make antibodies, and memory lymphocytes are made. If the person is later infected, the memory cells cause antibodies to be made quickly and in large amounts, so the virus is destroyed before they become ill.
Explain what is meant by herd immunity.
Mark scheme
- when a large proportion of the population is immune / vaccinated (1)
- the pathogen cannot spread, so unvaccinated people are protected (1)
Model answer
Herd immunity is when so many people are immune that the pathogen cannot spread, so the people who are not immune are also protected.
Babies under a few months old cannot be given the measles vaccine.
Explain why it is important that most other people are vaccinated.
Mark scheme
- herd immunity / fewer people can catch and pass on measles (1)
- so the babies are less likely to be infected (1)
Model answer
If most people are vaccinated, very few can catch and pass on measles, so the babies are unlikely to come into contact with the virus.
Give one disadvantage of vaccination.
Mark scheme
side effects / does not always give immunity / need boosters / new vaccines needed for changing pathogens
Model answer
Some people have side effects, such as a fever or swelling.
A new flu vaccine is needed each year. Suggest why.
Mark scheme
- the flu virus changes / mutates its antigens (1)
- so last year's antibodies / memory cells do not recognise it (1)
Model answer
The flu virus changes its antigens, so memory cells from last year's vaccine do not recognise the new strain.
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