Explain why a person who has recovered from a bacterial infection may still be at risk from a viral disease affecting the same organ.

Eduqas GCSE Biology — 3.1 Health and disease · Explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

A student recovers from a bacterial lung infection after taking a course of antibiotics. A few months later, the student catches influenza, a viral disease that also affects the lungs.

Model answer (4 marks)

Antibiotics only kill or inhibit bacterial pathogens, not viruses.
Bacteria and viruses are different types of pathogens, so the immune response to one does not recognise the other.
Recovery from the bacterial infection gives immunity only to that specific bacterium.
Because the student has not been exposed to influenza, no memory cells exist to protect against the viral infection.

Examiner tips

Use the word "antibiotics" and state they target bacteria only. Mention the difference between bacteria and viruses. Explain that immunity is pathogen‑specific. Note lack of prior exposure or vaccine for influenza.

Common mistakes

Confusing antibiotics with antiviral drugs. Claiming that immunity to one infection protects against all lung infections. Omitting that the student has not been vaccinated or previously exposed to influenza.

Mark scheme (4 marks)

Antibiotics only kill/treat bacterial pathogens (not viruses)
Viruses and bacteria are different types of pathogen
Immunity gained against bacterial pathogen does not protect against a different (viral) pathogen
There is no vaccine / the student has not been previously exposed to the influenza virus, so no memory cells are present

Key terms in this question

bacteria