White blood cells play an important role in defending the body against pathogens. Describe TWO ways in which white blood cells defend the body against pathogens.

WJEC GCSE Biology (Wales) — 2.8 Disease, defence and treatment · Describe · 4 marks · View as Markdown

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

Model answer (4 marks)

1. White blood cells can engulf and ingest pathogens by phagocytosis.
2. The engulfed pathogens are then digested and destroyed by enzymes within the white blood cell.
3. White blood cells produce antibodies that are specific to the pathogen’s antigens.
4. White blood cells also produce antitoxins that neutralise toxins released by pathogens.

Examiner tips

  • Use the exact terms ‘phagocytosis’, ‘antibodies’ and ‘antitoxins’ as they are explicitly rewarded.
  • Show the two mechanisms separately to match the four marks available.
  • Include the detail that enzymes digest the pathogen to secure full credit.
  • Keep the answer concise and avoid unnecessary explanation.

Common mistakes

  • Using vague words such as ‘eat’ instead of ‘phagocytosis’.
  • Failing to mention that antibodies are specific to antigens.
  • Omitting the role of enzymes in destroying engulfed pathogens.

Mark scheme (4 marks)

  1. White blood cells can engulf/ingest pathogens (phagocytosis)
  2. The pathogens are then digested/destroyed by enzymes inside the white blood cell
  3. White blood cells produce antibodies (that are specific to the pathogen's antigens)
  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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