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2.2 Animal tissues, organs and organ systems

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Question 10

Hepatitis B virus (HBV) can remain in liver cells for many years. Long-term HBV infection is a risk factor for liver cancer.

Scientists used health records to compare adults vaccinated against HBV before infection with adults who were not vaccinated. Both groups were followed for the same period.

OutcomeVaccinated against HBVNot vaccinated against HBV
Adults who developed long-term HBV infection (%)1.56.0
New cases of liver cancer per 100 000 adults1575
a.

Calculate the percentage reduction in the incidence of liver cancer in the vaccinated group compared with the group that was not vaccinated.

[2]
b.

Use the data and your knowledge of vaccination to explain how the vaccine could have produced the difference in liver cancer incidence. Evaluate whether the results prove that vaccination caused the difference.

[4]
Markscheme

2.2 Animal tissues, organs and organ systems Questions

  1. GCSE
  2. /Biology
  3. /2.2 Animal tissues, organs and organ systems

304 exam-style questions on AQA GCSE Biology 2.2 Animal tissues, organs and organ systems, covering 2.2.1 The human digestive system, 2.2.2 The heart and blood vessels, 2.2.3 Blood, 2.2.4 Coronary heart disease: a non-communicable disease, 2.2.5 Health issues, 2.2.6 The effect of lifestyle on some non-communicable diseases, and 2.2.7 Cancer. Each one has a worked solution and a mark scheme showing where the marks go.

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