Practise 33 exam-style questions on Communicable (infectious) diseases 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.
33 questions
2–5 marks each
Instant marking
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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
What is meant by a 'pathogen'?
Model answer
A pathogen is a microorganism or agent that causes disease (in plants or animals).
Explanation
Pathogens are disease-causing organisms or agents, such as bacteria, viruses, fungi or protists, that cause illness in hosts.
A virus infects a person’s cell. Explain briefly how the virus causes damage to that cell.
Model answer
Viruses enter host cells and use the cell's machinery to replicate, producing many new viruses which can burst (lyse) the cell or disrupt cell functions, causing damage.
Explanation
Viruses replicate inside cells using host processes; high numbers of new virions and interruption of cellular processes can kill or damage the infected cell.
Mark scheme
1 mark
virus enters and uses host cell machinery to replicate
1 mark
many new viruses produced inside the cell
1 mark
cell damaged or ruptures / cell function disrupted
Allow lysis or bursting.
Question 3
4 marks
Describe how bacteria cause disease in the body. Mention reproduction and toxins in your answer.
Model answer
Bacteria reproduce rapidly by binary fission, increasing numbers in the body. Many bacteria release toxins (poisons) that damage tissues and make us feel ill.
Explanation
Bacteria multiply quickly inside the body, increasing the infectious load. Many species produce toxins that damage host tissues and cause symptoms such as fever, pain, or organ dysfunction.
Mark scheme
1 mark
bacteria reproduce rapidly (in the body)
Expected: binary fission or rapid multiplication.
1 mark
this increases bacterial numbers
1 mark
bacteria produce toxins / poisons
Accept exotoxins/endotoxins named or described.
1 mark
toxins damage tissues / cause symptoms
Question 4
4 marks
Explain how rapid antigenic change (mutation) in a virus can affect the control of disease by vaccination.
Model answer
Mutation may alter viral antigens so antibodies from vaccination bind less well. Vaccines become less effective and may need updating; herd immunity may fall, allowing more infections.
Explanation
When antigens change, immune memory may be less protective, reducing vaccine efficacy and requiring revised vaccines to maintain control.
Mark scheme
1 mark
virus mutates / antigen changes
1 mark
antibodies from vaccine may not recognise new antigens
1 mark
vaccine effectiveness reduced / vaccine may need updating
1 mark
reduced herd immunity increases risk of spread
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