# Describe how the human body defends itself against pathogens. Include both non-specific defences and the role of white blood cells in your answer.

> WJEC A-Level Biology (Wales) — 3.3 Microbiology · Describe · 5 marks

## Mark scheme (5 marks)

1. Named non-specific mechanical or chemical barrier
2. Phagocytes engulf/ingest and digest pathogens (phagocytosis)
3. Lymphocytes produce antibodies in response to antigens on the pathogen
4. Each antibody is specific to one antigen and binds to it to neutralise the pathogen
5. Memory cells remain after infection so a second exposure produces a faster immune response

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