IB Biology SL C3.2.16 Vaccines and Immunization Questions

Practise interpreting antibody-response questions about vaccination, prior exposure and immunity in IB Biology SL C3.2.16.

[Maximum number: 2]

The image shows a castor bean tick (Ixodes ricinus) which is commonly found in woodlands or forest areas. This tick can carry bacteria that cause Lyme disease in humans.

Close-up photograph of a tick, showing an oval patterned body, projecting mouthparts and four pairs of jointed legs.

(a)

A vaccine has been developed to protect people against the symptoms of Lyme disease.
The graph shows the relative number of antibodies specific to these bacteria in the blood of a person before vaccination.

Graph of relative antibody number in blood against time in years. A curve declines towards the point marked vaccination; the horizontal axis includes a break labelled many years.

Graph of relative antibody number in blood against time in years. The existing curve declines before the point marked vaccination; a broken horizontal axis extends towards many years later.

[ 2 ]

(i)

Suggest what can be concluded from the graph about the person before they were vaccinated.

[ 1 ]

(ii)

Sketch a line on the graph to show how the number of antibodies would change over time after vaccination.

[ 1 ]

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a	(person had been) previously infected / have immunity / have memory cells (to the bacterium);
b	had been bitten by an (infected) tick before;
c	their immunity is diminishing/reducing;

IB Biology SL C3.2.16 Vaccines and Immunization Questions question 1

Question (a)

Question (i)

Question (ii)