AQA GCSE Combined Science Foundation (8464), Foundation tier · Biology › Infection and response › Communicable diseases
Practise Vaccination. 8 exam-style questions plus unlimited generated ones on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
How a vaccine makes you immune to a disease before you catch it, and why vaccinating a large proportion of a population also protects people who are not vaccinated. Expect 'explain how vaccination prevents illness' (3 to 4 marks) and graphs or data on antibody levels.
Key facts
Vaccine = small quantity of a dead or inactive pathogen
Vaccine → white blood cells produce specific antibodies
Re-infection → white blood cells respond quickly → correct antibodies made → pathogen destroyed before illness
Second response: faster and much bigger than the first
Immune = able to destroy the pathogen before it causes illness
Vaccinate a large proportion of a population → the pathogen spreads much less (herd immunity)
MMR vaccine protects against measles, mumps and rubella
Notes
What a vaccine is
A vaccine contains small quantities of a dead or inactive form of a pathogen. It is often given by injection.
It cannot cause the disease, but it still carries the pathogen's antigens.
How vaccination protects you
diagram
The vaccine stimulates your white blood cells to produce antibodies specific to that pathogen.
Your white blood cells 'remember' the pathogen: some of them stay in your blood as memory cells.
If the same live pathogen enters your body later, your white blood cells respond quickly, producing the correct antibodies in large amounts.
The pathogens are destroyed before they can reproduce enough to make you ill. You are immune.
Without the vaccine, the first response to a pathogen is slow, so the pathogen has time to reproduce and make you ill.
Memory cells make the second response faster and much bigger.
Protecting the population
If a large proportion of a population is vaccinated, most people cannot be infected, so they cannot pass the pathogen on.
So the pathogen is unlikely to reach the few people who are not immune, e.g. babies too young to be vaccinated or people who cannot have the vaccine.
This is called herd immunity. It greatly reduces the spread of the disease.
Benefits and drawbacks
Benefits: prevents illness and deaths, and can stop epidemics. Smallpox has been wiped out worldwide by vaccination.
Drawbacks: a vaccine does not always make a person immune, and some people have side effects, which are usually mild.
A vaccine protects only against the pathogen(s) it was made from (the MMR vaccine contains three: measles, mumps and rubella). Some pathogens, such as the flu virus, change their antigens, so a new vaccine is needed.
How to answer each type of question
Explain how vaccination prevents illness
3 to 4 marksGrade 5
Say what is in the vaccine: a dead or inactive form of the pathogen.
Say that it stimulates white blood cells to produce antibodies.
Say that if the live pathogen enters later, white blood cells respond quickly.
Finish: the correct antibodies destroy the pathogen before it causes illness.
Example. Young children in the UK are vaccinated against measles. Explain how the vaccine protects a child from becoming ill with measles later.
Show the model answerHide the model answer
The vaccine contains a dead or inactive form of the measles virus (1). This stimulates white blood cells to produce antibodies against the virus (1). If the live measles virus enters the body later, the white blood cells respond quickly (1), producing the correct antibodies, which destroy the virus before it can cause illness (1).
Don’t lose marks
Saying the vaccine contains antibodies. It contains a dead or inactive pathogen; your white blood cells make the antibodies.
Saying vaccines cure a disease or kill the pathogen. They prevent illness; they do not treat an infection you already have.
Saying the antibodies from the vaccine stay in the blood for life. What lasts is the ability to make the correct antibodies quickly.
Writing 'the body becomes immune' without saying why: the white blood cells respond quickly and make the correct antibodies.
Writing 'antibiotics' when you mean 'antibodies'.
More tips
Memory tricks
Vaccine chain: dead or inactive pathogen → antibodies made → body 'remembers' → fast response next time → not ill.
Graph check: the second peak comes sooner, rises more steeply and goes much higher.
Herd immunity: the more people are immune, the fewer 'stepping stones' the pathogen has to spread.
Exam technique
A full answer on how vaccination works includes: dead or inactive pathogen, white blood cells, antibodies, a quick response on re-infection, and the pathogen destroyed before illness.
For antibody graphs, quote values: when each response starts and how high each peak is.
For the population, describe the effect on the unvaccinated: the pathogen is unlikely to reach them.
What each grade needs
What you need to be able to do, from the first marks up to the top grade.
Grade 3
State what a vaccine containsSmall quantities of a dead or inactive form of a pathogen.
Grade 4
Describe what a vaccine makes the body doIt stimulates white blood cells to produce antibodies against the pathogen.
Grade 5
Explain how vaccination prevents illnessIf the live pathogen enters later, white blood cells quickly make the correct antibodies and destroy it before it causes illness.
Quick recall
Cover the answers and test yourself. The app has these as flashcards that come back just before you'd forget them.
Vaccination can stop people becoming ill with some infectious diseases. Which type of blood cell responds to a vaccine?
White blood cells
Complete the sentence. A person whose body can destroy a pathogen quickly, before they become ill, is said to be .................... to that disease.
Immune
Which type of blood cell responds to the vaccine to provide this protection?
White blood cells
Sample questions
Written for this site in the style of AQA exam questions. They are not taken from real past papers.
Question 1Easy4 marks
Vaccination can stop people becoming ill with some infectious diseases.
(a) What does a vaccine contain? Tick (✓) one box.[1]
Antibiotics that kill the pathogen
Antibodies against the pathogen
Dead or inactive forms of the pathogen
Painkillers to reduce the symptoms
(b) Which type of blood cell responds to a vaccine?[1]
(c) What do these cells produce after vaccination?[1]
(d) Name one disease that most young children in the UK are vaccinated against.[1]
Show the answer and mark scheme
(a)Answer: Dead or inactive forms of the pathogen
(b)Answer: White blood cells
white blood cell
(c)Answer: Antibodies
antibodies
(d)Answer: Measles
measles
any other correct example, e.g. mumps / rubella / polio / tetanus / diphtheria / whooping cough
Question 2Medium7 marks
A child is vaccinated against a disease caused by a bacterium.
(a) Explain how vaccination stops the child becoming ill if the same bacterium enters the child’s body in the future.[4]
(b) Explain why the vaccine itself does not make the child ill.[1]
(c) The vaccine does not protect the child against diseases caused by other pathogens. Explain why.[2]
Show the answer and mark scheme
(a)
the vaccine contains a dead / inactive form of the bacterium
(this) stimulates white blood cells to produce (specific) antibodies
if the same bacterium enters the body, white blood cells respond quickly
(and) produce the correct antibodies rapidly / in large amounts
(so) the bacteria are destroyed before they can reproduce / cause illness
(b)
the bacteria in the vaccine are dead / inactive, so they cannot reproduce / cause disease
(c)
antibodies are specific (to one antigen / pathogen)
other pathogens have different antigens, so the antibodies do not bind to them