Influenza is a communicable disease caused by a virus. Explain how the body's non-specific defences prevent the influenza virus from entering and spreading within the body.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Influenza (flu) is spread when infected individuals cough or sneeze, releasing virus particles into the air. Every year, thousands of people in the UK are infected.
Model answer (5 marks)
1. Mucus in the airways traps influenza virus particles.
2. Cilia beat to move the mucus, together with trapped virus, upward toward the throat.
3. The mucus is swallowed and the stomach’s hydrochloric acid destroys any virus that reaches the stomach.
4. White blood cells in the bloodstream phagocytose any virus that has entered the body.
5. White blood cells also produce antibodies that neutralise viral toxins, and the skin provides a physical barrier to prevent entry.
2. Cilia beat to move the mucus, together with trapped virus, upward toward the throat.
3. The mucus is swallowed and the stomach’s hydrochloric acid destroys any virus that reaches the stomach.
4. White blood cells in the bloodstream phagocytose any virus that has entered the body.
5. White blood cells also produce antibodies that neutralise viral toxins, and the skin provides a physical barrier to prevent entry.
Examiner tips
- Use the exact terms ‘mucus’, ‘cilia’, ‘hydrochloric acid’, ‘phagocytosis’, and ‘antibodies’. Show the sequence from inhalation to destruction. Keep each point short and separate with numbers or bullet points.
Common mistakes
- Confusing the role of antibodies with antitoxins. Forgetting to mention the stomach’s acid. Using vague phrases like ‘immune system’ instead of specific cells or mechanisms.
Mark scheme (5 marks)
- Mucus in the airways traps virus particles / pathogens
- Cilia waft / move mucus (and trapped virus) upward / toward the throat so it can be swallowed or expelled
- Hydrochloric acid in the stomach kills any swallowed virus / pathogens
- White blood cells engulf / ingest / destroy pathogens that enter the body by phagocytosis
- White blood cells also produce antitoxins to neutralise any toxins produced by pathogens / OR skin acts as a physical barrier preventing virus entry
Key terms in this question
Related
- All Pearson Edexcel A-Level Biology A (9BI0) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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