Explain how white blood cells defend the body against pathogens.

Edexcel GCSE Biology (1BI0) — 8.2 Transport in animals (blood and circulation) · Explain · 4 marks · View as Markdown

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

The human body contains two main types of white blood cell: phagocytes and lymphocytes. Together these cells form part of the immune response when pathogens enter the body.

Model answer (4 marks)

Phagocytes engulf pathogens and then digest or break them down.
Lymphocytes produce antibodies that recognise specific antigens on the pathogen, and they can also produce antitoxins to neutralise toxins.

Examiner tips

  • Use the exact terms "phagocytes", "engulf", "digest", "lymphocytes", "antibodies", "antigens", "antitoxins". Show the two main actions of each cell type. Keep the answer concise – 4 marks, so one sentence per point. Use correct UK spelling (e.g. "recognise").

Common mistakes

  • Mixing up the roles of phagocytes and lymphocytes. Using vague words like "fight" or "kill" instead of "engulf" and "digest". Omitting the specificity of antibodies to antigens or the production of antitoxins.

Mark scheme (4 marks)

  1. Phagocytes engulf pathogens
  2. Phagocytes digest/break down the engulfed pathogens
  3. Lymphocytes produce antibodies
  4. Antibodies are specific to the pathogen's antigen / lymphocytes also produce antitoxins to neutralise toxins

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