DP Biology (first assessment 2025)

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Question 23M.2.SL.TZ2.d

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Date May 2023 Marks available [Maximum mark: 2] Reference code 23M.2.SL.TZ2.d
Level SL Paper 2 Time zone TZ2
Command term Outline Question number d Adapted from N/A
d.
[Maximum mark: 2]
23M.2.SL.TZ2.d

Children are immunized against diseases caused by Streptococcus pneumoniae with pneumococcal conjugate vaccine (PCV) and against diseases caused by Haemophilus influenzae with Haemophilus influenzae type b (Hib) vaccine.

The graphs show the estimated global percentages of children not vaccinated against S. pneumoniae and H. influenzae by the age of 5 and the estimated global death rates in children under 5 years, due to these pathogens, between 2000 and 2015.

[Source: Adapted from Wahl et al., 2018, Burden of Streptococcus pneumoniae and Haemophilus influenzae type b disease in children in the era of conjugate vaccines: global, regional, and national estimates for 2000–15. The Lancet Global Health 6 (7), E744-757. https://www.thelancet.com/journals/langlo/article/PIIS2214-109X(18)30247-X/fulltext. Open access.]

Outline the conclusions that can be drawn from the graph showing data for PCV and S. pneumoniae.

[2]

Markscheme
  1. number of deaths (due to S. pneumoniae) and percentage of children not vaccinated (with PCV) both fall (along the years)
    OR
    number of deaths (due to S. pneumoniae) decreases while percentage of vaccinated children (with PCV) increases (along the years);
  2. positive correlation between number of deaths and percentage of children not vaccinated /
    OR
    negative correlation between number of deaths and percentage of children vaccinated / vaccination reduces the number of deaths;
  3. increased reduction in the number of deaths from 2010 onwards;
  4. still large number of deaths/large number of children unvaccinated in 2015;

Comparative terms expected (do not award mp for just stating values).

Mpb: do not allow “directly or inversely proportional”.

Mpb: Do not just accept “positive correlation” or “negative correlation” without a clear indication of the variables being correlated

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