Explain how white blood cells protect the body when a pathogen enters the bloodstream.

WJEC GCSE Biology (Wales) — 2.6.2 The immune system · Explain · 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 protect the body by
1. engulfing and digesting pathogens through phagocytosis.
2. producing antibodies that recognise and bind to specific antigens on the pathogen.
3. the antibody–antigen complexes neutralise the pathogen and mark it for destruction.
4. some white blood cells produce antitoxins that neutralise toxins released by pathogens.

Examiner tips

  • Use the word ‘engulf’ for phagocytosis, ‘recognise’ for antibody specificity, and mention ‘neutralise’ for antitoxins.
  • Show the sequence: phagocytosis → antibody production → binding → neutralisation.
  • Keep each point short and use exam‑specific terminology.

Mark scheme (4 marks)

  1. White blood cells can engulf and digest pathogens (phagocytosis)
  2. White blood cells produce antibodies
  3. Antibodies are specific to / bind to antigens on the pathogen
  4. White blood cells produce antitoxins that neutralise toxins released by pathogens

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