Describe the role of white blood cells in defending the body against pathogens after they have entered the bloodstream.

AQA GCSE Biology (8461) — 4.3.1 Communicable diseases · Describe · 4 marks · View as Markdown

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

Model answer (4 marks)

White blood cells (leukocytes) defend the body by:
1. Engulfing and digesting pathogens through phagocytosis.
2. Producing antibodies that recognise specific pathogens.
3. Antibodies causing pathogens to clump together or neutralise them, and marking them for destruction.
4. Producing antitoxins that neutralise toxins released by pathogens.

Examiner tips

  • Use the exact terminology: phagocytosis, antibodies, antitoxins. Include the four actions in separate points to match the 4 marks. Show the link between antibodies and marking pathogens for destruction.

Common mistakes

  • Confusing antibodies with antitoxins. Failing to mention phagocytosis. Using vague terms like "immune response" instead of specific actions.

Mark scheme (4 marks)

  1. White blood cells can engulf and digest pathogens (phagocytosis)
  2. White blood cells produce antibodies that target specific pathogens
  3. Antibodies cause pathogens to clump together or neutralise them / mark pathogens for destruction
  4. White blood cells produce antitoxins that neutralise toxins released by pathogens

Key terms in this question

white blood cells · pathogens

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