Infection and ResponseAQA GCSE Biology (8461)

Communicable Diseases

Work through the notes, try the practice questions, then take the quiz. The report tells you exactly what to revise next. (2026)

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Practice — Communicable Diseases

1
Which of the following best defines a pathogen?
Answer & explanation
Correct: option B
AQA's spec definition: 'pathogen — a microorganism that causes an infectious disease'. Toxins are released by some pathogens but are not pathogens themselves.
2
How do bacteria typically cause symptoms of disease?
Answer & explanation
Correct: option C
Bacteria reproduce rapidly inside the body and release toxins; these damage tissues and cause symptoms. Option A is the viral mechanism.
3
Which of these is NOT one of the four pathogen groups named by AQA?
Answer & explanation
Correct: option D
AQA names bacteria, viruses, fungi and protists. Algae are not classed as a pathogen group on the spec.
4
Malaria is spread by the female Anopheles mosquito. The mosquito is best described as:
Answer & explanation
Correct: option C
A vector is an organism that carries a pathogen from one host to another. The mosquito itself isn't ill — it carries the protist that causes malaria.
5
Which strategy would best reduce the spread of an airborne viral infection in a school?
Answer & explanation
Correct: option B
Airborne droplet spread is interrupted by ventilation, masks and isolation of cases. The other options target waterborne, vector-borne and foodborne routes.
6
Why do bacteria cause symptoms so quickly after entering the body?
Answer & explanation
Correct: option B
Bacteria can double in number every ~20 minutes under ideal conditions, so toxin production quickly reaches the level needed to cause symptoms.
7
Which disease is NOT a communicable disease?
Answer & explanation
Correct: option C
Coronary heart disease is non-communicable — it is not caused by a pathogen. The other three are caused by a bacterium, virus and protist respectively.

Infection and ResponseAQA GCSE Biology (8461)

Communicable Diseases

Work through the notes, try the practice questions, then take the quiz. The report tells you exactly what to revise next. (2026)

PreviousNext

Practice progress

7 MCQs

0 of 7 attempted

Correct

Incorrect

Remaining

Practice — Communicable Diseases

1
Which of the following best defines a pathogen?
Answer & explanation
Correct: option B
AQA's spec definition: 'pathogen — a microorganism that causes an infectious disease'. Toxins are released by some pathogens but are not pathogens themselves.
2
How do bacteria typically cause symptoms of disease?
Answer & explanation
Correct: option C
Bacteria reproduce rapidly inside the body and release toxins; these damage tissues and cause symptoms. Option A is the viral mechanism.
3
Which of these is NOT one of the four pathogen groups named by AQA?
Answer & explanation
Correct: option D
AQA names bacteria, viruses, fungi and protists. Algae are not classed as a pathogen group on the spec.
4
Malaria is spread by the female Anopheles mosquito. The mosquito is best described as:
Answer & explanation
Correct: option C
A vector is an organism that carries a pathogen from one host to another. The mosquito itself isn't ill — it carries the protist that causes malaria.
5
Which strategy would best reduce the spread of an airborne viral infection in a school?
Answer & explanation
Correct: option B
Airborne droplet spread is interrupted by ventilation, masks and isolation of cases. The other options target waterborne, vector-borne and foodborne routes.
6
Why do bacteria cause symptoms so quickly after entering the body?
Answer & explanation
Correct: option B
Bacteria can double in number every ~20 minutes under ideal conditions, so toxin production quickly reaches the level needed to cause symptoms.
7
Which disease is NOT a communicable disease?
Answer & explanation
Correct: option C
Coronary heart disease is non-communicable — it is not caused by a pathogen. The other three are caused by a bacterium, virus and protist respectively.