Evaluate a controlled cutting-establishment investigation
Interpret an explicit outcome without claiming genetic or practical proof.
Section 16.1 · Asexual reproduction
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
- Recall cells, DNA, inherited characteristics and the distinction between growth of an organism and production of offspring.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
Which outcome matches establishment here?
What you will learn
- Define a reproducible establishment outcome
- Control comparisons and judge repeats
Evaluate a controlled cutting-establishment investigation
Invented criterion: roots plus a new shoot by the same time. A 16/20 = 80%; B 12/20 = 60%; difference 20 percentage points. Original teaching model.
| Group | Starting total | Established |
|---|---|---|
| A | 20 | 16 |
| B | 20 | 12 |
| Feature | Meaning |
|---|---|
| Outcome | Roots and new shoot by a defined time |
| Controls | Donor, size, water, medium, temperature and time |
| Data | A 80%; B 60% established |
| Limit | No direct genotype, disease-free, yield or practical-competence proof |
Define a reproducible establishment outcome
A supplied investigation compares growing conditions for cuttings from the same donor clone. Establishment is defined as roots and a new shoot by the stated observation time. Define this outcome before counting: a merely green stem or swollen bud is not silently treated as an established plant. Both groups still use vegetative asexual propagation; the changed condition does not create a different reproductive mechanism.
Use the same plant type and donor source, comparable cutting size and age, medium, water, containers and observation time, apart from the condition being changed. Random allocation and repeated groups reduce bias. In a light comparison, do not also change temperature and watering without acknowledging those extra variables. Explain how a control makes the outcome comparison more interpretable.
Control comparisons and judge repeats
In an invented record, 16 of 20 cuttings establish in A and 12 of 20 in B at the same time. Establishment percentages are 80% and 60%, a difference of 20 percentage points. This supports a higher fraction in A for these groups; repeated comparisons and outcome variation are needed before claiming a reliable general effect. Percentages need the number supplied to each group as denominator.
The count does not directly measure genotype, disease freedom, adult yield or every future cutting’s success. A common donor helps control genetic differences but does not equalise all environmental factors. A written plan and calculation do not demonstrate supervised practical competence; learners interpret supplied information rather than being directed to use tools or grow microorganisms unsupervised.
Pause and explain
Why use the same donor source?
Worked example
Compare establishment when A has 16/20 and B has 12/20.
Show the worked solution
- Calculate each fraction as a percentage.
- Subtract the percentages.
Answer A 80%; B 60%; difference 20 percentage points.
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.
Calculate establishment percentages from 16/20 in A and 12/20 in B.
Give me a hint
Use the supplied group totals.
Compare my reasoning
- 16/20×100 = 80%.
- 12/20×100 = 60%.
A 80%; B 60%; difference 20 percentage points.
Look for these in your work
- Use group denominators
- State percentage-point difference
Name two controls for a comparison changing only light condition.
Give me a hint
Keep other establishment factors comparable.
Compare my reasoning
- Use comparable donor source and cutting size.
- Equalise water, medium, temperature and time.
Examples: the same donor source; comparable cutting size; equal medium, water and temperature; the same observation period.
Look for these in your work
- Name relevant controls
- Keep the changed condition distinct
Does the count prove disease freedom, genotype identity or practical competence?
Give me a hint
Match the conclusion to establishment measured here.
Compare my reasoning
- Those other outcomes are not measured.
- Written interpretation is not supervised performance.
No. The record counts establishment only; it does not prove disease freedom, genotype identity or supervised practical competence.
Look for these in your work
- Match claim to outcome
- Retain evidence and practical limits
Common mistakes
- Counting green stems as the defined outcome.
- Treating one comparison as universal proof.
What can you explain now?
Why use the same donor source?
Compare with the explanation
To help control genetic differences between groups
Other factors still need control.
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Make it stick
Define establishment, calculate percentages and identify the limits of one supplied comparison.
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.