Practise 30 exam-style questions on bacterial 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.
30 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
3 marks
Describe briefly how Salmonella causes symptoms in the gut.
Model answer
Bacteria invade gut lining and produce toxins that damage cells, causing inflammation; this leads to vomiting and diarrhoea and abdominal pain.
Explanation
Salmonella multiplies and its toxins damage gut cells, causing inflammation and the typical gastrointestinal symptoms.
Mark scheme
1 mark
bacteria / Salmonella infect or invade the gut lining
Name one public health reason for making sexually transmitted infections (including gonorrhoea) notifiable in many countries.
Model answer
To enable surveillance and monitoring of incidence and outbreaks and to direct public health resources and interventions such as contact tracing.
Explanation
Notification permits timely public health responses, surveillance and resource targeting to control infectious disease spread.
Mark scheme
1 mark
to allow surveillance / monitoring of cases and outbreaks
1 mark
to enable public health action (contact tracing / targeted interventions)
1 mark
to help control spread and allocate resources
Question 3
4 marks
List two aseptic techniques that should be used when culturing bacteria on agar plates.
Model answer
Flaming loops, sterilising equipment, working near a Bunsen flame or in a clean hood, keeping lids closed, disinfecting bench, washing hands.
Explanation
Aseptic technique prevents contamination of cultures and reduces risk of accidental spread: sterilising equipment, limiting exposure and disinfecting surfaces are key steps.
Mark scheme
1 mark
sterilise loop/needle before and after use (e.g. flame)
1 mark
minimise plate exposure / keep lids closed / open briefly
1 mark
work near a flame / in a sterile cabinet or disinfect bench
1 mark
dispose of materials safely and sterilise equipment / wash hands
Question 4
5 marks
Explain how antibiotic resistance arises and why it is a concern for treating bacterial STDs such as gonorrhoea.
Model answer
Random mutations can give bacteria resistance; antibiotics kill sensitive bacteria but resistant ones survive and reproduce, spreading resistance genes. This makes previously effective antibiotics (e.g. penicillin) fail, so gonorrhoea becomes harder to treat and may spread.
Explanation
Resistance emerges by mutation and selection; surviving resistant strains propagate. This reduces treatment options for gonorrhoea and risks more widespread untreatable infections.
Mark scheme
1 mark
random mutation or gene transfer can produce resistance in bacteria
