Human defence systems - AQA GCSE Biology Exam Questions

Practise 31 exam-style questions on Human defence systems for AQA GCSE Biology. Write your answer as you would in the exam and get it marked in seconds against the mark scheme, point by point, with an AI tutor on hand if you get stuck.

31 questions
1–4 marks each
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20 questions, marked as you go

Sample questions with model answers

Here are 4 of the questions in this topic, each with a model answer, an explanation of why it earns the marks and the mark scheme an examiner would use.

Question 1

2 marks

Explain how the trachea and bronchi help prevent infection in the lungs.

Model answer

lined with ciliated epithelial cells and mucus; cilia move mucus-trapped pathogens out of the airways

Explanation

Goblet cells produce mucus which traps microbes; ciliated cells beat to move the mucus up towards the throat where it is swallowed or expelled, clearing pathogens.

Mark scheme

1 mark
mucus traps pathogens
1 mark
cilia move mucus out of the airways
Must mention movement of trapped particles by cilia.

Question 2

2 marks

What is meant by 'antibiotic stewardship'?

Model answer

strategies to use antibiotics responsibly to reduce resistance — e.g., appropriate prescribing, correct dose and duration, avoiding unnecessary use

Explanation

Antibiotic stewardship aims to preserve antibiotic effectiveness by ensuring they are used only when necessary and in the right way to limit development of resistance.

Mark scheme

1 mark
responsible use of antibiotics to reduce resistance
1 mark
includes appropriate prescribing, dose and duration / avoid unnecessary use

Question 3

3 marks

Explain how herd immunity works and how it helps protect people who cannot be vaccinated.

Model answer

when a high proportion are immune (via vaccination) pathogen spread is limited; there are fewer susceptible people and transmission chains break; this reduces exposure risk for those who are unvaccinated or immune-compromised

Explanation

Herd immunity occurs when most of a population is immune, reducing pathogen circulation and indirectly protecting the vulnerable who cannot develop immunity themselves.

Mark scheme

1 mark
large proportion immune reduces spread
1 mark
fewer susceptible people breaks transmission chains
1 mark
protects those who cannot be vaccinated by reducing their chance of exposure

Question 4

4 marks

Describe how memory cells and antibodies act together to prevent reinfection.

Model answer

on first exposure B cells produce antibodies and form memory cells; on re-exposure memory cells quickly differentiate into plasma cells producing large amounts of specific antibodies; rapid high antibody level neutralises pathogen before disease

Explanation

Memory cells enable a faster secondary immune response, producing antibodies rapidly in larger quantities which clear the pathogen before symptoms develop.

Mark scheme

1 mark
first exposure produces antibodies and memory cells
1 mark
memory cells persist after initial infection
1 mark
on re-exposure memory cells rapidly make plasma cells/antibodies
1 mark
rapid high antibody levels neutralise pathogen preventing disease

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