Evaluate original stem-cell descendant records with clear evidence limits
Invented descendant counts: six F and four G out of ten give sixty and forty per cent, a twenty-percentage-point difference. They establish no universal potential, division rate or treatment result.
Section B16.2 · Cell division
Mapped to the named 0654 section using teaching from the corresponding single-science course. A 0654-specific review of every Core and Supplement objective is still in progress. Written practice is self-checked; it does not demonstrate supervised laboratory competence or award an official Cambridge grade.
Before you begin
- Recall chromosomes, genes, chromosome sets, selective gene expression and the distinction between a nucleus and a whole cell.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
Six of ten descendants show type F features. What is the observed proportion?
What you will learn
- Interpret the observed specialised outcomes
- Avoid unsupported universal or clinical claims
Original teaching model. Counts and records are stipulated; drawings are schematic.
| Feature | Meaning |
|---|---|
| Observed descendants | 10 total: 6 F and 4 G |
| F proportion | 60% of the observed record |
| G proportion | 40%; difference 20 percentage points |
| Limit | No universal potential, timed rate or clinical outcome |
Interpret the observed specialised outcomes
An original fictional record follows ten descendants from a labelled stem-cell population. Six later show the supplied features of specialised type F, and four show the supplied features of type G. The record supports those two observed outcomes under the stated conditions. It does not demonstrate that the population can produce every other type of cell.
The proportions are six out of ten, or sixty per cent, for F and four out of ten, or forty per cent, for G. Their difference is twenty percentage points, not a twenty-per-cent relative increase. The record counts observed descendant states and supplies no times, so it does not establish a mitotic division rate or the probability of all future outcomes.
Avoid unsupported universal or clinical claims
A stem-cell explanation also needs the connection between an unspecialised source, mitotic daughter-cell production and potential specialisation. Shape observations alone do not directly test every chromosome sequence or exclude all alternative lineage histories. The teaching record stipulates its source and normal division so you can practise the stated mechanism without presenting those stipulations as laboratory proof.
These invented proportions are not results of a human trial, treatment success rates or instructions for cell culture. A real claim would need appropriate population identification, lineage evidence, controls and repeated observations. Within this lesson, give the supported conclusion, the denominator and the missing evidence rather than expanding a small record into a promise of universal biological or clinical performance.
Sources for this lesson
Pause and explain
What does the fictional F/G record establish within its scope?
Worked example
Ten descendants include six F and four G. What observed proportions apply?
Show the worked solution
- Use ten as the denominator for both.
- Compare percentage points separately.
Answer F is sixty per cent, G is forty per cent and the difference is twenty 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 the observed F and G percentages from six F and four G descendants out of ten.
Give me a hint
Use the same denominator.
Compare my reasoning
- Calculate six divided by ten times one hundred.
- Calculate four divided by ten times one hundred.
F is sixty per cent and G is forty per cent of the ten observed descendants.
Look for these in your work
- Show both denominators
- Label observed proportions
Calculate the percentage-point difference between those proportions and distinguish it from a guaranteed future outcome.
Give me a hint
Subtract the observed percentages.
Compare my reasoning
- Calculate sixty minus forty.
- Keep the result limited to the supplied record.
The difference is twenty percentage points in this observed fictional record; it does not guarantee the proportions of future descendants.
Look for these in your work
- Use percentage points
- Retain the record limit
A claim says the ten descendants prove the source can form every body-cell type and cure a disease. Evaluate it.
Give me a hint
Compare the claimed scope with the observed F/G outcomes.
Compare my reasoning
- Identify that only F and G are observed.
- State that other potential and treatment outcomes are untested.
The claim is unsupported. The record shows only the supplied F and G outcomes, not every cell type or clinical treatment success.
Look for these in your work
- Identify the overreach
- State what is actually supported
Common mistakes
- Observed proportions are not guaranteed future probabilities.
- Two supported types do not establish every possible cell type.
What can you explain now?
What does the fictional F/G record establish within its scope?
Compare with the explanation
The two observed outcomes under the stated conditions
The record is limited to the given descendants.
After trying it yourself, choose your next review. This is your self-assessment.
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Make it stick
Without your notes, interpret the observed specialised outcomes and avoid unsupported universal or clinical claims. Distinguish nuclear division, chromosome copies and completed daughter cells before opening the solutions.
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.