Describe radiation effects on living cells
Connect ionisation to cell death mutations and cancer risk without inferring an outcome from raw counts.
Exam scope and assessment notes
Core and Extended · Physics 0972, 2026–2028. Use labelled nuclides, supplied count intervals and stated background conditions. Model drawings are not to scale. Written practice is self-checked. Human subject-teacher review, supervised practical competence and cumulative assessment remain pending. Cambridge states that IGCSE 0972 has the same subject content as IGCSE 0625, 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
- Understand ionisation energy transfer.
- Distinguish irradiation and contamination.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
Which statement describes a possible radiation effect?
What you will learn
- Connect ionisation to cell death mutations and cancer risk without inferring an outcome from raw counts.
- Describe biological radiation effects and distinguish risk, counts and source location.
Identify the possible effects
Ionising radiation can damage living cells. It may kill cells or damage genetic material, producing mutations. Some mutations can contribute to cancer. An exposure increases risk under relevant conditions; it does not mean every irradiated person will develop cancer.
The effect depends on the energy absorbed, tissue, radiation type and exposure conditions. An uncalibrated detector count is not itself a patient dose or a diagnosis.
Locate internal and external exposure
An external source irradiates from outside. Contamination puts radioactive material on or inside an object or person, where continued emission can give ongoing exposure. Alpha is readily stopped outside the body but can be damaging if an alpha-emitting material is inside living tissue.
Do not use the usual penetration order as a universal biological-risk ranking. The source location and absorbed energy matter. Source incidents belong to trained authorised staff, not independent student experiments or cleanup.
Pause and explain
Is alpha always harmless because it is easily stopped externally?
Worked example
Name three possible effects of ionising radiation on living cells.
Show the worked solution
- Cells may be killed.
- Genetic material may be mutated.
- Some mutations can lead to cancer.
Answer Cell death, mutations and increased cancer risk.
Try a topic test
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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.
List the three syllabus biological effects.
Give me a hint
Include cell survival and genetic consequences.
Compare my reasoning
- Cell damage can cause death.
- DNA damage can cause mutation.
- Some mutations can contribute to cancer.
Cell death, mutations and cancer risk.
Look for these in your work
- Name all three.
- Do not claim certainty.
Explain why an internal alpha source can be hazardous despite low penetration.
Give me a hint
Locate its ionising track relative to cells.
Compare my reasoning
- The source is within tissue.
- Alpha spends energy over a short nearby track.
- Living cells can receive dense ionisation.
Short-range alpha ionisation can damage nearby tissue from an internal source.
Look for these in your work
- State source location.
- Connect energy deposition to cells.
A detector records 100 ticks and a report diagnoses cancer from this alone. Evaluate it.
Give me a hint
Check dose calibration and clinical evidence.
Compare my reasoning
- Raw ticks are detected events.
- They do not establish tissue dose or individual biological outcome.
- A diagnosis needs appropriate clinical evidence.
The count alone does not support that diagnosis.
Look for these in your work
- Separate count and dose.
- Avoid an unsupported individual outcome.
Common mistakes
- Risk is not certainty.
- Counts are not automatically dose.
- Internal alpha can be harmful.
What can you explain now?
Can ionising radiation damage genetic material?
Compare with the explanation
Yes
Energy transfer can cause mutations in living cells.
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Make it stick
Describe biological radiation effects and distinguish risk, counts and source location.
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.