How white blood cells defend the body and how vaccination works. The 6-mark vaccination question appeared in Jun 2023 — a chain-of-events style answer is required.
FreeScienceLessons · AQA BiologyImmunity — antibodies, vaccination, white blood cells
Key facts
How white blood cells defend the body
Phagocytes — engulf and digest pathogens (phagocytosis)
Lymphocytes — produce antibodies specific to the pathogen's antigens
Antibodies are complementary to antigens on the pathogen's surface
Antibodies bind to antigens → pathogen clumped/destroyed
Memory cells remain after infection — allows faster response if same pathogen returns
Vaccination — how it works
Dead, weakened or partial pathogen is injected
White blood cells produce specific antibodies
Memory cells are formed
If real pathogen enters: antibodies produced rapidly and in large numbers
Pathogen destroyed before illness develops
Herd immunity — if enough people are vaccinated, the pathogen cannot spread
Secondary immune response — why vaccines work long-term
First exposure (vaccine): primary response — slow, produces antibodies and memory cells
Second exposure (real infection): secondary response — fast, large number of antibodies produced immediately
Memory cells "remember" the antigen and respond instantly
Mark scheme language: "antibodies produced quickly / in large numbers" — both parts needed for marks
Exam questions — 4 questions · 11 marks total
⚡ This module includes extended questions (4–6 marks). These are where most marks are lost. Use the hint button if you are stuck. Write in full sentences. The AI will tell you exactly which mark scheme points you missed.
1 markWhite blood cellsAQA 8461 style
Which type of white blood cell produces antibodies?
A Phagocytes
B Lymphocytes
C Red blood cells
D Platelets
2 marksAntibodiesAQA Jun 2023 P1 style
Explain why antibodies produced against one pathogen will not protect against a different pathogen. (2 marks)
+20 XP
6 marksExtended response — vaccination chainAQA Jun 2023 P1 — real 6-mark question
Chickens can be vaccinated against Salmonella bacteria to reduce food poisoning outbreaks in humans. Explain how vaccinating chickens reduces the risk of humans getting food poisoning from Salmonella. (6 marks)
How to get Level 3 (5–6 marks): This is a chain of events question. You must cover: (1) what happens in the chicken when vaccinated, (2) what happens if the chicken is later exposed to Salmonella, and (3) how this prevents humans getting food poisoning. Link each stage clearly.
+60 XP
2 marksHerd immunityAQA 8461 style
Explain what is meant by herd immunity and why it is important. (2 marks)