AQA GCSE Biology Foundation (8461), Foundation tier · Infection and response › Communicable diseases
Practise Bacterial diseases. 7 exam-style questions on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
The two bacterial diseases of humans in the specification: Salmonella food poisoning and gonorrhoea. You need their symptoms, how they are spread and how their spread is controlled, including why gonorrhoea is now harder to treat.
Key facts
Salmonella: bacteria swallowed in contaminated food
Salmonella symptoms: fever, abdominal cramps, vomiting, diarrhoea (from the bacteria and their toxins)
UK poultry are vaccinated against Salmonella
Gonorrhoea: STD caused by a bacterium, spread by sexual contact
Gonorrhoea symptoms: thick yellow or green discharge, pain on urinating
Gonorrhoea control: antibiotics and condoms
Many strains of the gonorrhoea bacterium are now resistant to penicillin
Notes
Salmonella food poisoning
diagram
Caused by Salmonella bacteria that are swallowed in food, or on food prepared in unhygienic conditions.
Symptoms: fever, abdominal cramps, vomiting and diarrhoea. These are caused by the bacteria and the toxins they secrete.
In the UK, poultry (e.g. chickens) are vaccinated against Salmonella to control the spread.
Hygienic food preparation also reduces spread: cook food thoroughly to kill the bacteria, wash hands, clean surfaces, and keep raw meat away from food that will not be cooked.
Each control measure breaks a link in the chain.
Gonorrhoea
A sexually transmitted disease (STD) caused by a bacterium. It is spread by sexual contact.
Symptoms: a thick yellow or green discharge from the vagina or penis, and pain on urinating.
It used to be easily treated with the antibiotic penicillin, until many resistant strains appeared. Penicillin does not kill these strains.
The spread is controlled by treating infected people with antibiotics and by using a barrier method of contraception such as a condom, which stops the bacteria passing between partners.
Bacteria and treatment
Bacteria reproduce rapidly inside the body and may release toxins that damage tissues.
Bacterial diseases can be treated with antibiotics, but the antibiotic must be one that kills that particular bacterium, and it will not work on a resistant strain.
How to answer each type of question
Give symptoms and their cause
1 to 3 marksGrade 4
Learn the four Salmonella symptoms and the two gonorrhoea symptoms.
If asked what causes the symptoms, mention the toxins.
Example. (a) Give two symptoms of Salmonella food poisoning. (b) What causes these symptoms?
Show the model answerHide the model answer
(a) Any two from: fever, abdominal cramps, vomiting, diarrhoea (1) (1) (b) The bacteria and the toxins they secrete (1)
Suggest how to reduce food poisoning
2 to 4 marksGrade 5
Give a specific hygiene method (cook thoroughly, wash hands, separate raw meat, clean surfaces).
For each method, explain how it kills the bacteria or stops them reaching food that will be eaten.
Example. A restaurant was linked to an outbreak of Salmonella food poisoning. Suggest two ways the restaurant could reduce the risk of this happening again. Give a reason for each.
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Cook chicken and eggs thoroughly (1), so the high temperature kills the bacteria (1). Keep raw meat away from cooked or ready-to-eat food, e.g. use separate chopping boards (1), so bacteria are not transferred to food that will not be cooked (1).
Don’t lose marks
Calling Salmonella or gonorrhoea a virus. Both are caused by bacteria.
Writing just 'be more hygienic'. Name the method (cook thoroughly, wash hands, keep raw meat separate) and say how it helps.
Saying gonorrhoea is spread by blood or through the air. It is spread by sexual contact.
Saying the bacteria 'become immune' to penicillin. Bacteria become resistant; immunity is something your body develops.
Saying any contraceptive stops gonorrhoea. Only a barrier method, such as a condom, stops the bacteria being passed on.
More tips
Memory tricks
Salmonella = stomach trouble: cramps, vomiting and diarrhoea, plus fever.
Gonorrhoea = 'discharge and pain': thick yellow or green discharge and pain on urinating.
Both are bacteria, so both can be treated with antibiotics, unless the strain is resistant.
Exam technique
When asked why the symptoms happen, mention toxins: the bacteria secrete toxins that damage tissues.
Use 'resistant', not 'immune', for bacteria that are not killed by an antibiotic.
For every control measure, give the reason: say how it stops the bacteria reaching the next person.
What each grade needs
What you need to be able to do, from the first marks up to the top grade.
Grade 3
Name two bacterial diseasesSalmonella food poisoning and gonorrhoea, a sexually transmitted disease.
Grade 4
Give the symptoms of Salmonella food poisoningFever, abdominal cramps, vomiting and diarrhoea, caused by the bacteria and the toxins they secrete.
Grade 4
Give the symptoms of gonorrhoeaA thick yellow or green discharge from the vagina or penis, and pain on urinating.
Grade 5
Describe how each disease is spreadSalmonella: bacteria swallowed in food or on food prepared in unhygienic conditions; gonorrhoea: sexual contact.
Grade 5
Describe how the spread of each is controlledVaccinating poultry and hygienic food preparation for Salmonella; antibiotics and condoms for gonorrhoea.
Quick recall
Cover the answers and test yourself. The app has these as flashcards that come back just before you'd forget them.
Salmonella is a type of bacterium that causes food poisoning. Give two symptoms of Salmonella food poisoning.
Any two from: fever, abdominal cramps, vomiting, diarrhoea.
Gonorrhoea is a sexually transmitted disease (STD). What type of pathogen causes gonorrhoea?
A bacterium
Salmonella food poisoning and gonorrhoea are both diseases caused by bacteria. Give two symptoms of Salmonella food poisoning.
Any two from: fever, abdominal cramps, vomiting, diarrhoea.
What name is given to an animal, such as a tick, that spreads a pathogen from one host to another?
Vector
Sample questions
Written for this site in the style of AQA exam questions. They are not taken from real past papers.
Question 1Easy5 marks
Salmonella is a type of bacterium that causes food poisoning.
(a) Give two symptoms of Salmonella food poisoning.[2]
(b) The symptoms are caused by the bacteria and by poisonous substances that the bacteria secrete. What name is given to these poisonous substances?[1]
(c) How is Salmonella usually spread to humans? Tick (✓) one box.[1]
By inhaling droplets from coughs and sneezes
By eating food containing the bacteria
By the bite of an infected insect
By sexual contact
(d) Give one way the spread of Salmonella is controlled in the UK.[1]
Show the answer and mark scheme
(a)Answer: Any two from: fever, abdominal cramps, vomiting, diarrhoea.
fever / high temperature
abdominal cramps / stomach pains
vomiting
diarrhoea
(b)Answer: Toxins
toxins
(c)Answer: By eating food containing the bacteria
(d)Answer: Poultry are vaccinated against Salmonella.
vaccinating poultry / chickens
cooking food (especially chicken and eggs) thoroughly
preparing food in hygienic conditions / washing hands before handling food
Question 2Medium7 marks
Gonorrhoea is a sexually transmitted disease (STD).
(a) What type of pathogen causes gonorrhoea?[1]
(b) Give two symptoms of gonorrhoea.[2]
(c) Gonorrhoea used to be easily treated with the antibiotic penicillin. Explain why penicillin is no longer used to treat gonorrhoea.[2]
(d) Give two ways the spread of gonorrhoea can be controlled.[2]
Show the answer and mark scheme
(a)Answer: A bacterium
bacterium / bacteria
(b)Answer: A thick yellow or green discharge from the vagina or penis; pain when urinating.
thick yellow / green discharge from the vagina / penis
pain on urinating
(c)
many strains of the bacterium are (now) resistant to penicillin
(so) penicillin would not kill the bacteria / would not cure the infection
(d)
treating infected people with an (effective) antibiotic
using a barrier method of contraception / condoms
testing and treating the sexual partners of infected people