Describe antibiotics as treatments for bacterial infections
Distinguish antibacterial action from other medicines and immune defences.
Section 15.1 · Drugs
Exam scope and assessment notes
Core and Extended · Biology 0970, 2026–2028. Use the stated specimen features and evidence. Diagrams are schematic. Written practice is self-checked; human subject-teacher review, supervised practical competence and cumulative assessment remain pending. Cambridge states that IGCSE 0970 has the same subject content as IGCSE 0610, with 9–1 grading. This StudyForA pathway maps the 2026–2028 syllabus only. This 9–1 graded qualification is available only in a limited number of administrative zones. Confirm that your centre can enter you for this code and exam series with Cambridge International. Cambridge has published a separate syllabus for 2029. StudyForA has not reconciled that version yet; this page supports exams in 2026, 2027 and 2028 only.
Before you begin
- Distinguish bacteria from viruses; recall enzymes, chemical reactions, pathogens and reproduction of bacteria.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
Which infection category can be treated by an appropriate antibiotic?
What you will learn
- Name the relevant pathogen category
- Use susceptibility and clinical need as separate ideas
Describe antibiotics as treatments for bacterial infections
| Feature | Meaning |
|---|---|
| Target category | Bacteria, not viruses |
| Susceptible | Affected by the specified antibiotic |
| Distinct roles | Drug, antibody and vaccine are not interchangeable |
| Need | Not every bacterial infection requires antibiotics |
Further reading: CDC explanation of appropriate antibiotic use.
Name the relevant pathogen category
Antibiotics are used to treat certain infections caused by bacteria. The syllabus contrast is that antibiotics kill bacteria but do not act against viruses. In the supplied teaching models, a specified antibiotic kills susceptible bacteria. Susceptible means affected by that particular antibiotic; resistant bacteria may survive. Some antibacterial drugs inhibit bacterial growth rather than directly killing, so do not claim that every antibiotic has an identical mechanism.
An antibiotic is not an antibody. Antibiotics are drugs, whereas antibodies are proteins produced through immune responses and bind to particular antigens. Vaccination prepares immune protection and is not the same as taking an antibiotic to treat an existing bacterial infection. A pain-relieving medicine may reduce a symptom without killing the pathogen; effect categories should not be merged.
Use susceptibility and clinical need as separate ideas
Identifying a bacterial cause does not automatically mean that every infection requires antibiotics. Appropriate clinical use depends on the infection and professional assessment. For a school question, use the stated pathogen identity and susceptibility evidence to predict antibacterial action, without replacing those facts with an assumption from symptoms alone.
A supplied bacterial infection caused by a susceptible strain can be consistent with antibiotic treatment, whereas a supplied virus-only infection does not provide a bacterial target for the drug. This is a biological distinction rather than a prescription for a real person. Explain the drug’s target category and retain any stated resistance limit; the later Supplement sequence explains why unnecessary use can increase selection for resistant bacteria.
Pause and explain
Which distinction is correct?
Worked example
Classify the intended target of an antibiotic in a supplied susceptible-infection model.
Show the worked solution
- The infection is caused by bacteria.
- The stated antibiotic can kill the susceptible bacteria.
Answer The antibiotic targets susceptible bacteria in the supplied bacterial infection model.
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Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
State the infection category for which antibiotics are used.
Give me a hint
Name the pathogen type.
Compare my reasoning
- Antibiotics act against bacteria.
- They are used for appropriate bacterial infections.
Antibiotics are used to treat certain bacterial infections.
Look for these in your work
- Name bacterial infections
- Retain appropriate use
Distinguish an antibiotic, an antibody and a vaccine.
Give me a hint
Separate drug, immune protein and immune preparation.
Compare my reasoning
- An antibiotic is an antibacterial drug; an antibody is an immune protein.
- A vaccine prepares immune protection.
Antibiotic: antibacterial drug. Antibody: immune protein binding specific antigens. Vaccine: preparation used to develop immune protection.
Look for these in your work
- Distinguish all three categories
- Avoid merging treatment and immune preparation
A supplied infection is bacterial but no need or susceptibility information is given. Does that establish that any antibiotic is appropriate?
Give me a hint
Pathogen category is only part of the evidence.
Compare my reasoning
- Not every bacterial infection requires antibiotics.
- Drug suitability and susceptibility need assessment.
No. Bacterial identity alone does not establish need or suitability of any antibiotic; susceptibility and appropriate clinical assessment also matter.
Look for these in your work
- Reject automatic use
- Identify the missing suitability evidence
Common mistakes
- Calling antibiotics antibodies or vaccines.
- Assuming every bacterial infection automatically requires an antibiotic.
What can you explain now?
Which distinction is correct?
Compare with the explanation
Antibiotics are drugs; antibodies are immune proteins
They are different categories.
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Make it stick
Describe appropriate antibacterial use and distinguish antibiotics from immune proteins and vaccines.
If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.