An SPM Science question about infection tests concepts: what a pathogen is, how it spreads and how spread is reduced. It does not ask you to diagnose or treat a real person.
This lesson is part of microorganisms. It pairs with comparing microorganism groups for the group definitions.
What does the syllabus ask about infection?
Keep to three ideas: what causes the disease, how it passes on, and how spread is reduced. These three answer most questions.
| Idea | Curriculum wording | Example |
|---|---|---|
| Cause | A pathogen invades the body | A virus or a bacterium |
| Spread | Air droplets, contact, food and water, vectors | Mosquito carries a pathogen |
| Prevention | Hygiene, clean water, vaccination, vector control | Washing hands, covering coughs |
These are scientific concepts. They are not a replacement for seeing a doctor.
Worked example: a school scenario
Question: A school reports that five students have fever and cough. Explain how the pathogen may spread and suggest two ways to reduce spread.
Step 1: identify the spread route. If the pathogen spreads through the air, droplets from coughing can reach other students.
Step 2: give concept-level prevention. Covering the mouth when coughing reduces droplets. Regular hand washing removes pathogens from the hands.
Step 3: stay within the question. The question asks about spread and prevention. It does not ask which disease it is, so do not name one or suggest a treatment.
A full answer is: “Droplets from coughing can carry the pathogen to others. Covering the mouth and washing hands reduce the spread.”
Where does the exam stop and medical advice begin?
An exam answer talks about patterns in general. Medical advice depends on a particular person, their history and a doctor’s examination.
If a question says “a patient has these symptoms, what is the disease?”, read it as a test of concepts, such as “symptoms are caused by the pathogen”. A real illness needs a real doctor.
The mistake that costs marks
Two slips show up. One is to go beyond the question, such as prescribing a medicine. The other is to stay too vague, such as “keep clean”.
| Wrong | Right |
|---|---|
| Take antibiotics for the cough | Explain how the pathogen spreads, because treatment is not asked |
| Keep clean | Wash hands to remove pathogens before eating |
| The student has a certain disease | The symptoms are caused by a pathogen that has invaded the body |
Answer what is asked, at the level of the concept, using the terms pathogen, spread and prevention.
Check yourself
A question says a fish pond has a mosquito problem and asks you to explain how mosquitoes spread a disease and how to reduce the spread. Answer at curriculum level.
Answer
A mosquito is a vector. It carries a pathogen from an infected person and passes it to another person when it bites.
To reduce spread, remove standing water where mosquitoes lay eggs, and use nets or repellent to prevent bites.
What to study next
Test the four lessons together with the microorganisms practice set. The mistake log and paper-error review helps you see which scenario wording trips you up.
To practise scenario answers with a teacher, see online one-to-one Science tuition.