Fig. 8.1 shows the results of a study of the human immune response after a person was given a vaccine. The person was given a first dose of the vaccine at w...
Question 1 Report
Fig. 8.1 shows the results of a study of the human immune response after a person was given a vaccine. The person was given a first dose of the vaccine at week 0 and a second, booster, dose at week 6. Scientists measured the concentration of antibodies against the disease in the blood at different times. The vaccine contained weakened forms of the pathogen so that the body could learn to defend itself without becoming ill. The concentrations of antibody measured are shown in the table.
| Time / weeks | Antibody concentration / arbitrary units |
|---|---|
| 0 | 0 |
| 2 | 18 |
| 6 | 6 |
| 8 | 70 |
| 10 | 60 |
(a) State what is meant by the term pathogen. [1]
(b) Using the data, describe how the antibody response after the booster dose at week 6 differs from the response after the first dose. [2]
(c) Explain, in terms of memory cells, why the antibody response after the booster dose is faster and greater. [3]
Answer Details
This question is about the primary and secondary immune responses after vaccination.
(a) [1] A pathogen is a microorganism (organism) that causes disease [1].
(b) [2] After the booster dose at week 6 the antibody concentration rises to a much higher level than after the first dose (about 70 compared with 18 units) [1]; and it rises more quickly, sooner after the injection [1].
(c) [3] The first dose caused the body to make memory cells [1]; these long-lived cells remain in the blood and immediately recognise the pathogen's antigen when it is met again at the booster [1]; so they divide rapidly to produce the correct antibodies faster and in far greater amounts (the secondary response) [1].
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