Question 1
Paper 4 short-answer style1 markState how many cells are produced from one parent cell by meiosis. (1 mark)
Model answer
Four.
Why this scores
One mark for 'four'.
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Detailed notes on Inheritance for Cambridge IGCSE Biology, covering key concepts, explanations, examples, and exam-focused revision points.
Cell division to make GAMETES. Halves the chromosome number. Introduces variation between offspring.
Mapped to the Cambridge IGCSE 0610 syllabus (2026-2028).
1 diploid cell → 4 haploid genetically different daughter cells. Used to make gametes.
Definition. Meiosis = nuclear division producing FOUR genetically DIFFERENT daughter cells, each with HALF the chromosome number of the parent cell.
Why halve the chromosome number?
Where it happens.
The two stages.
(IGCSE doesn't go into the prophase/metaphase detail. Just know the outcome.)
Worked qualitative. A human cell with 46 chromosomes goes through meiosis. How many chromosomes do the resulting gametes have?
Cambridge tip. Always state '4 different daughter cells' AND 'half chromosome number'. Both are key.
Random assortment + crossing over → each gamete unique.
Two main mechanisms create genetic variation between gametes:
1. Random assortment.
2. Crossing over.
3. Random fertilisation.
Total variation. Between random assortment + crossing over + random fertilisation, the genetic combinations possible from two parents are essentially infinite. That's why siblings (except identical twins) are never identical.
Worked qualitative. Why are identical twins genetically identical?
Cambridge tip. When asked HOW meiosis produces variation, give random assortment + crossing over. Saying 'because gametes are different' is circular.
Mitosis = same. Meiosis = halved. Different roles.
| Feature | Mitosis | Meiosis |
|---|---|---|
| Daughter cells | 2 | 4 |
| Chromosome number | Same as parent | Halved |
| Diploid → ? | Diploid | Haploid |
| Genetic identity | Identical clones | All different |
| Where | All body cells (most tissues) | Reproductive tissues only |
| Purpose | Growth, repair, asexual | Make gametes for sexual reproduction |
| Variation | None | Yes (assortment + crossing over) |
Worked qualitative. Could a body cell suddenly do meiosis instead of mitosis?
Cambridge tip. Cambridge often gives a 'compare and contrast' table. Memorise it row by row.
Verbatim phrases and definitions Cambridge mark schemes credit.
Meiosis appears Paper 4 (5-7 marks: define, contrast with mitosis, explain variation). Examiner reports flag students saying meiosis makes 2 daughters and missing the 'genetically different' point.
Sources: Cambridge IGCSE Biology 0610 syllabus 2026-2028 (17.4); 0610/42 Oct/Nov 2024 — Q18 (meiosis); 0610 Examiner Reports 2022-2024. Last reviewed 2026-05-07.
Step-by-step solutions to past-paper-style questions on meiosis, written exactly the way a tutor would explain them at the board.
Question
Define meiosis and state its outcome.
Step-by-step solution
Step 1
Meiosis is a reduction division in which the chromosome number is halved, from diploid to haploid.
Step 2
It produces cells that are genetically different from each other and from the parent cell.
Step 3
These cells are the gametes (sex cells).
Answer
Meiosis is a reduction division that halves the chromosome number (diploid → haploid), producing genetically different gametes.
Question
State (a) what meiosis produces and (b) where in the human body it takes place.
Step-by-step solution
Step 1
(a) Meiosis produces the gametes — the sperm and the eggs.
Step 2
(b) In humans it takes place in the reproductive organs — the testes (to make sperm) and the ovaries (to make eggs).
Answer
(a) Meiosis produces gametes (sperm and eggs); (b) it happens in the reproductive organs — the testes and ovaries.
Examiner tip
Meiosis is restricted to the reproductive organs; the rest of the body uses mitosis.
Question
Compare mitosis and meiosis.
Step-by-step solution
Step 1
Number of cells: mitosis produces 2 daughter cells; meiosis produces 4.
Step 2
Chromosome number: mitosis keeps it the same; meiosis halves it.
Step 3
Genetic identity: mitosis produces identical cells; meiosis produces genetically different cells.
Step 4
Use: mitosis is for growth, repair and asexual reproduction; meiosis is for producing gametes.
Answer
Mitosis: 2 identical cells, same chromosome number, for growth/repair. Meiosis: 4 different cells, half the chromosome number, for gametes.
Question
Explain why the gametes produced by meiosis are genetically different from one another.
Step-by-step solution
Step 1
During meiosis, the pairs of chromosomes are separated, and which chromosome of each pair goes into which gamete is random.
Step 2
So each gamete receives a different combination of chromosomes (and therefore a different combination of alleles).
Step 3
There are many possible combinations, so each gamete is likely to be genetically unique.
Step 4
This is why the gametes — and therefore the offspring produced from them — show genetic variation.
Answer
Meiosis separates the chromosome pairs randomly, so each gamete gets a different combination of chromosomes and alleles — making the gametes genetically different.
Examiner tip
The key idea is the random combination of chromosomes (alleles) in each gamete.
Question
Explain why it is important that meiosis halves the chromosome number when making gametes.
Step-by-step solution
Step 1
Body cells are diploid (e.g. 46 chromosomes in humans).
Step 2
Meiosis makes the gametes haploid (e.g. 23 chromosomes) — half the number.
Step 3
At fertilisation, a male gamete fuses with a female gamete, so the chromosomes from both are combined.
Step 4
Because each gamete has half the number, the zygote has the full diploid number restored (23 + 23 = 46). If meiosis did not halve the number, the zygote would have double the correct number, which would keep doubling each generation.
Answer
Gametes are made haploid (half the number) so that, when two fuse at fertilisation, the diploid number is restored. Otherwise the chromosome number would double each generation.
Examiner tip
Link the halving to keeping the chromosome number constant across the generations.
Question
Explain how meiosis and fertilisation together produce genetic variation in the offspring.
Step-by-step solution
Step 1
During meiosis, the chromosomes are separated randomly, so each gamete receives a different combination of alleles.
Step 2
This means a parent produces many genetically different gametes.
Step 3
At fertilisation, it is a matter of chance which male gamete fuses with which female gamete.
Step 4
So each offspring receives a new, random combination of alleles from two parents — producing genetic variation between the offspring.
Answer
Meiosis makes genetically different gametes (random combination of alleles), and at fertilisation any two gametes can fuse by chance, so each offspring has a new combination of alleles — giving variation.
Examiner tip
Two sources of variation: random combination of alleles in gametes (meiosis) and random fertilisation.
High-scoring sample answers for meiosis on the Cambridge IGCSE 0610 paper, with examiner-style notes mapping each response to the mark scheme and assessment objectives.
State how many cells are produced from one parent cell by meiosis. (1 mark)
Model answer
Four.
Why this scores
One mark for 'four'.
State two differences between mitosis and meiosis. (2 marks)
Model answer
Mitosis produces two daughter cells with the same chromosome number, whereas meiosis produces four cells with half the chromosome number. (Also: mitosis produces genetically identical cells; meiosis produces genetically different cells.)
Why this scores
Two genuine differences, each comparing both: number of cells; chromosome number; genetic identity; use.
Explain why meiosis is described as a reduction division, and why this is important. (3 marks)
Model answer
Meiosis is called a reduction division because it halves the chromosome number — the gametes it makes are haploid, with half the number found in the diploid parent cell. This is important because, when two gametes fuse at fertilisation, the full diploid chromosome number is restored in the zygote, keeping the chromosome number constant from one generation to the next.
Why this scores
Three marks: halves the number / gametes are haploid; fertilisation restores the diploid number; keeps the chromosome number constant.
Compare mitosis and meiosis in terms of the number of cells produced, the chromosome number, whether the cells are genetically identical, and where each is used. (4 marks)
Model answer
Mitosis produces two daughter cells, each with the same chromosome number as the parent, and they are genetically identical; it is used for growth, repair and asexual reproduction. Meiosis produces four cells, each with half the chromosome number, and they are genetically different; it is used to produce gametes.
Why this scores
Four marks: number of cells (2 vs 4); chromosome number (same vs halved); identical vs different; uses (growth/repair vs gametes).
Explain how meiosis and fertilisation together lead to genetic variation among offspring. (5 marks)
Model answer
During meiosis, the chromosome pairs are separated randomly, so each gamete receives a different combination of chromosomes, and therefore a different combination of alleles. This means a parent makes many genetically different gametes. At fertilisation, it is a matter of chance which male gamete fuses with which female gamete. So each offspring receives a new, random combination of alleles, half from each parent. Because the combination is different each time, the offspring vary genetically from one another and from their parents.
Why this scores
Five marks: meiosis separates chromosomes randomly; gametes get different combinations of alleles; many different gametes; random fertilisation; new combination of alleles → variation.
Explain the role of meiosis in producing gametes and in keeping the chromosome number of a species constant from generation to generation. (6 marks)
Model answer
Meiosis takes place in the reproductive organs and produces the gametes (sperm and eggs). It is a reduction division: it produces four cells, each with half the chromosome number of the diploid parent cell, so the gametes are haploid. The chromosome pairs are separated randomly during meiosis, so each gamete carries a different combination of alleles, which is why the gametes are genetically different. Because the gametes are haploid, when a male gamete and a female gamete fuse at fertilisation, their chromosomes are combined and the full diploid number is restored in the zygote (for example 23 + 23 = 46 in humans). This keeps the chromosome number of the species constant from one generation to the next: if meiosis did not halve the number first, the chromosome number would double each generation, which would be harmful. So meiosis both produces the gametes needed for sexual reproduction and ensures the chromosome number stays constant.
Why this scores
Up to 6 marks: meiosis makes gametes; reduction division → four haploid cells; chromosomes separated randomly → genetically different gametes; haploid gametes fuse at fertilisation; diploid number restored; keeps number constant / otherwise it would double.
Definitions to memorise and the exact keywords mark schemes credit for meiosis answers — sharpened from recent examiner reports for the 2026 0610 sitting.
A reduction division that halves the chromosome number (diploid → haploid), producing four genetically different cells (the gametes).
Having one set of chromosomes (e.g. 23 in humans). Gametes are haploid; they are the products of meiosis.
Another name for meiosis, because it reduces (halves) the chromosome number.
The traps other students keep falling into on meiosis questions — taken from recent Cambridge IGCSE 0610 examiner reports and mark schemes — and how to avoid them.
Why it happens
Mitosis produces two.
How to avoid it
Meiosis produces FOUR cells (it involves two divisions). Mitosis produces two.
Why it happens
All cells divide at some point.
How to avoid it
Meiosis happens only in the reproductive organs (testes, ovaries; flowers in plants). Body cells use mitosis.
Why it happens
Students mix it up with mitosis.
How to avoid it
Meiosis produces genetically DIFFERENT cells. Mitosis produces identical cells.
The things students keep getting wrong in this sub-topic, answered.