Describe how the immune system responds when a pathogen enters the body for the first time.

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)

White blood cells and lymphocytes recognise the antigen on the pathogen’s surface.
Antibodies that are specific to that antigen are produced.
The antibodies bind to the pathogen, leading to its destruction or neutralisation.
Memory cells are formed, so a faster response occurs if the same pathogen is encountered again.

Examiner tips

  • Use the exact terms: white blood cells, lymphocytes, antigen, antibodies, memory cells. Show the sequence: detection → antibody production → action → memory. Keep each point short and to the point to hit all four marks.

Common mistakes

  • Confusing antibodies with T‑cells or B‑cells. Omitting the role of memory cells. Using vague language such as ‘immune response’ without detail.

Mark scheme (4 marks)

  1. White blood cells / lymphocytes detect the antigen on the surface of the pathogen
  2. Antibodies are produced that are specific / complementary to the antigen
  3. Antibodies bind to / destroy / neutralise the pathogen
  4. Memory cells are produced so the response is faster if the same pathogen is encountered again

Key terms in this question

pathogen

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