Distinguish two daughter nuclei from two completed daughter cells
Two nuclei can be present inside one represented cell. Separate outer boundaries are needed to count two completed daughter cells in this model.
Section 17.2 · Mitosis
Exam scope and assessment notes
Extended only (Supplement) · 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 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
What directly establishes two completed daughter cells in the drawing?
What you will learn
- Read nuclear and cell boundaries
- Count the completed products
Original teaching model. Counts and records are stipulated; drawings are schematic.
| Feature | Meaning |
|---|---|
| Nuclear division | One nucleus produces two daughter nuclei |
| Cytoplasmic division | Usually follows to make two separate cells |
| Nuclear-only record | Five cells with two nuclei each: ten nuclei |
| Completed-cycle record | Six parents give twelve daughters |
Read nuclear and cell boundaries
Mitosis concerns the nucleus. When an original diagram shows two nuclear boundaries inside one continuous cell boundary, it shows two nuclei within one represented cell. It does not yet show two separate daughter cells. The subsequent partition of cytoplasm and the cell boundary normally completes the two-cell outcome used in the simple mitotic model.
A parent cell with one nucleus can therefore be represented in three conceptual snapshots: chromosome copying before division, two daughter nuclei after nuclear division and two daughter cells after the cytoplasm is partitioned. These are teaching snapshots rather than named mitotic stages. Use the labels and boundaries provided instead of guessing timing from the colours of the drawing.
Count the completed products
For a stipulated completed cycle, one parent cell becomes two daughters, so the cell population increases by one. For a nuclear-only observation, that same increase has not yet been demonstrated. If five original cells each contain two nuclei but still have five continuous outer boundaries, the record represents ten nuclei in five cells at that moment.
Some biological contexts have multiple nuclei without the simple immediate two-cell outcome. This lesson does not claim that all nuclear division must instantly produce two separate cells. The important exam explanation is that mitosis is nuclear division, while ordinary daughter-cell formation also needs the subsequent division of cytoplasm. Keep the observation separate from the model's expected next event.
Pause and explain
Five continuous cell boundaries each contain two nuclei. What is represented?
Worked example
A drawing has two nuclei inside one outer boundary. How many represented cells are visible?
Show the worked solution
- Count outer boundaries.
- Count nuclear boundaries separately.
Answer One cell and two nuclei are represented; completed cytoplasmic division is not shown.
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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.
A snapshot shows one cell boundary and two nuclear boundaries. State both counts.
Give me a hint
Count each boundary category.
Compare my reasoning
- Count the outer cell boundary.
- Count the nuclear boundaries.
The snapshot represents one cell containing two nuclei.
Look for these in your work
- State both counts
- Keep the categories separate
Six parent cells each complete one normal nuclear division and subsequent cell division. How many daughter cells result?
Give me a hint
Each completed cycle gives two cells.
Compare my reasoning
- Use two daughter cells per parent.
- Multiply six by two.
Twelve daughter cells result from six completed cycles; the net increase is six cells.
Look for these in your work
- Use completed cycles
- Distinguish total and net increase
Six cells each contain two nuclei but have not divided their cytoplasm. Can the same record be reported as twelve cells?
Give me a hint
Use the outer boundaries.
Compare my reasoning
- Identify six continuous cell boundaries.
- Separate twelve nuclei from completed cell products.
No. The record represents six cells and twelve nuclei; it does not yet show twelve separate cells.
Look for these in your work
- Retain the observed cell count
- State what remains unshown
Common mistakes
- Do not count a nucleus as a whole cell.
- Two nuclei need not prove two completed daughter cells.
What can you explain now?
Five continuous cell boundaries each contain two nuclei. What is represented?
Compare with the explanation
Five cells and ten nuclei
Count the two boundary types separately.
After trying it yourself, choose your next review. This is your self-assessment.
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Make it stick
Without your notes, read nuclear and cell boundaries and count the completed products. 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.