Apply a stated antibiotic response table
Use pathogen identity and drug-specific evidence without prescribing.
Cross-referenced to the 2028–2029 0653 section using original teaching from the related single-science courses. A 0653-specific objective-by-objective and Core/Supplement review is in progress. Written practice is self-checked and does not demonstrate supervised laboratory competence or award an official Cambridge grade.
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 target has no direct response to either antibiotic in this table?
What you will learn
- Predict biological effects from a labelled model
- Separate action evidence from treatment decisions
Apply a stated antibiotic response table
Invented effect table: S responds to A and B; R resists A but responds to B; virus V responds to neither antibiotic. Predict effects, not a personal prescription. Original teaching model.
| Target | Antibiotic A | Antibiotic B |
|---|---|---|
| Bacterial strain S | Affected | Affected |
| Bacterial strain R | Resistant | Affected |
| Virus V | No direct effect | No direct effect |
| Feature | Meaning |
|---|---|
| Strain S | Affected by A and B |
| Strain R | Resistant to A; affected by B |
| Virus V | No direct effect from either antibiotic |
| Limit | Effect table does not establish treatment need or dose |
Predict biological effects from a labelled model
The supplied comparison table is an invented biological model with three targets and two antibiotics. Bacterial strain S is affected by A and B. Bacterial strain R is resistant to A but affected by B. Virus V is not affected by either antibiotic. Read both the target category and the individual drug column; the word infection alone does not specify which effect is predicted.
For strain S, both A and B have a stated antibacterial effect in the model. For strain R, A does not have the stated effect but B does. Resistance to A therefore does not establish resistance to B. For virus V, neither antibiotic has a direct antiviral effect. These predictions follow from the supplied table rather than symptoms, colour or an assumption that a stronger drug must affect every pathogen.
Separate action evidence from treatment decisions
A table of biological effects is not a complete clinical selection rule. It does not supply treatment need, side effects, allergies, dose, route or other professional considerations. In the school task, report the predicted effect under the stated conditions rather than instructing a real learner to take A or B. The antibiotic names are deliberately abstract so the exercise remains about target reasoning.
A symptom-relieving drug, an antibody and an antibiotic may be discussed together but have different roles. An improvement in how an organism feels is not the same measurement as whether bacteria or viruses are eliminated. Explain the table’s direct effect and its limits. A secondary bacterial infection during a viral illness would be a separate bacterial target, not evidence that an antibiotic kills the virus.
Sources for this lesson
Pause and explain
What does the table establish about R?
Worked example
Predict A and B effects on strain R from the supplied table.
Show the worked solution
- R is resistant to A.
- R is affected by B in the model.
Answer A has no stated effect on R; B affects R under the supplied model conditions.
Try a topic test
Choose Easy, Normal or Difficult. Save your answers and open worked review after finishing.
Test this topic →From guided practice to a new situation
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 model effects of A and B on each target.
Give me a hint
Read both columns for all three targets.
Compare my reasoning
- S is affected by A and B; R is resistant to A but affected by B.
- Virus V is unaffected by both antibiotics.
S: A and B affect it. R: A does not, B does. Virus V: neither antibiotic has a direct effect.
Look for these in your work
- Read all three targets
- Keep drug-specific effects
Explain why R’s resistance to A does not establish resistance to B.
Give me a hint
Use the separate model evidence.
Compare my reasoning
- The resistance is relative to A.
- The table states an effect from B.
Resistance is relative to the specified drug; the table separately states that B affects R, so R’s A resistance does not imply B resistance.
Look for these in your work
- Specify the drug reference
- Use the separate B result
A learner uses the table to choose a personal medication and dose. What important evidence is absent?
Give me a hint
The exercise supplies effects, not a clinical assessment.
Compare my reasoning
- Treatment need and personal suitability are not established.
- No dose or other clinical considerations are supplied.
The table does not establish personal treatment need, suitability or dose. Its predictions are biological model effects, not a prescription.
Look for these in your work
- Identify missing clinical evidence
- Retain the model-only conclusion
Common mistakes
- Treating resistance to one drug as resistance to both.
- Turning a model table into a personal prescription.
What can you explain now?
What does the table establish about R?
Compare with the explanation
Resistance to A with a separate stated response to B
Responses must be read by drug.
After trying it yourself, choose your next review. This is your self-assessment.
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Make it stick
Apply a drug-specific response table and explain what it cannot establish about personal treatment.
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.