Describe the role of phagocytes and lymphocytes in destroying a pathogen that has entered the body for the first time.

Eduqas A-Level Biology — 3.3 Microbiology · Describe · 5 marks · View as Markdown

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

Model answer (5 marks)

1. Phagocytes engulf and ingest the pathogen.
2. Phagocytes digest the pathogen using enzymes in phagosomes (phagocytosis).
3. Lymphocytes recognise antigens on the pathogen surface.
4. Lymphocytes produce and release antibodies that are specific to the antigen.
5. Memory cells are formed, enabling a faster response if the same pathogen re‑enters.

Examiner tips

Use the exact terms: phagocytes, engulf, digest, lymphocytes, antigen, antibodies, memory cells.
Show the sequence: phagocytosis → antigen recognition → antibody production → memory cell formation.
Keep each point concise and separate with numbers or bullet points.

Common mistakes

Confusing phagocytes with lymphocytes or vice versa.
Failing to mention that antibodies are specific to the antigen.
Omitting the role of memory cells in secondary immune response.

Mark scheme (5 marks)

Phagocytes engulf/ingest the pathogen
Phagocytes digest the pathogen using enzymes (phagocytosis)
Lymphocytes detect antigens on the surface of the pathogen
Lymphocytes produce/release antibodies that are specific/complementary to the antigen
Memory cells are produced so that if the same pathogen enters the body again, it is destroyed more quickly

Key terms in this question

phagocyte · lymphocyte