The shape of the lesson
By the end of the lesson, learners can
- Making gametes: The sim cell is in an ovary or testis.
- Mitosis or meiosis?: Many exam questions ask you to compare the two divisions.
- Meiosis is involved in producing gametes (sperm, eggs, pollen nuclei).
- Extended: reduction division, diploid → haploid (46 → 23 in humans).
- Extended: the gametes are genetically different; mitosis gives identical cells.
- Fertilisation restores the diploid number: haploid + haploid = diploid zygote.
One picture every idea returns to
Meiosis is involved in the production of gametes. Extended: it is a reduction division in which the chromosome number is halved from diploid to haploid, resulting in genetically different cells.
Forty-five minutes, phase by phase
| Time | Phase | What happens in the room | Grouping |
|---|---|---|---|
| 0 to 5 min | Hook: predict | Open with the question in the title, Halving the number, shuffling the set.. Gametes are not made by mitosis. Put the figure on the board: it is the one picture every idea in the lesson returns to. | Whole class, then pairs |
| 5 to 17 min | Teach and check: Making gametes | The sim cell is in an ovary or testis. Project tab 6 of the lab (Meiosis step by step) and let a student drive it while the class predicts. | Whole class, then pairs |
| 17 to 30 min | Teach and check: Mitosis or meiosis? | Many exam questions ask you to compare the two divisions. | Cooperative Concept Mapping |
| 30 to 36 min | Check | The four Stage 1 questions from the student lesson, answered on mini whiteboards or by show of fingers. Re-teach the one most get wrong. | Individual, then whole class |
| 36 to 43 min | Plenary | The exam-style questions from Stage 2, one at a time: thirty seconds alone, then a random call. The feedback lines in the key give the examiner's wording. | Individual, random call |
| 43 to 45 min | Exit and homework | Set the worksheet below (6 questions, 17 marks). Learners self-assess against the objectives before they leave. | Individual |
Protect the parts that carry the learning
The sequence carries about fifty minutes of material, so the lab is driven by one student while the class predicts rather than explored freely. Times are a guide.
Protected: the check at 30 minutes. It is the only individual read on whether the key idea landed, and it is not cut.
Cut first if the build overruns: the last check in Mitosis or meiosis?, never the check or the plenary.
In a 60 minute block: run worksheet questions 1 to 3 in class as a Rally Coach set and model both the hardest worked example and its check live.
Cooperative Concept Mapping
Teams receive the key terms on cards and arrange them on a large sheet, drawing and labelling the links. Compare maps between teams before showing the model map.
The full structure, with its variations and the other twelve, is on the cooperative-learning page.
What to head off, and how
| Trap learners fall into | Teaching move that pre-empts it |
|---|---|
| Haploid does not mean half a chromosome or half of each chromosome. | It means a single set: one whole chromosome of each type. |
| The zygote divides by mitosis, not meiosis. | Meiosis happens only when gametes are being made. |
Meiosis: worksheet
6 questions, 17 marks. Written in the style of the papers; no past paper question is reproduced.
State where meiosis happens in a human male and in a flowering plant.
Extended. Describe what is meant by a reduction division, using the terms diploid and haploid.
Extended. Give four differences between mitosis and meiosis.
Extended. A species of fruit fly has 8 chromosomes in each body cell. State the number of chromosomes in (a) a sperm cell, (b) a zygote, (c) a cell in the gut lining after mitosis.
Extended. Explain why gametes need to be haploid.
Extended. Brothers and sisters with the same parents are not genetically identical (unless they are identical twins). Use your knowledge of meiosis to explain why.
Answer key and marking notes
- In the testes (where sperm are made).
- In the anthers (to make pollen) and in the ovules (to make egg cells).
- A nuclear division (meiosis) in which the chromosome number is halved.
- From diploid, two sets of chromosomes (46 in humans),
- to haploid, a single set of chromosomes (23 in humans).
- Mitosis gives genetically identical cells; meiosis gives genetically different cells.
- Mitosis keeps the chromosome number the same; meiosis halves it (diploid to haploid).
- Mitosis is used for growth, repair, replacement and asexual reproduction; meiosis is used to make gametes.
- Mitosis gives two cells from each division; meiosis gives four cells from one parent cell.
- (a) 4 (haploid, 8 ÷ 2).
- (b) 8 (diploid: a 4-chromosome sperm fuses with a 4-chromosome egg).
- (c) 8 (mitosis keeps the chromosome number the same).
- At fertilisation two gametes fuse to form a zygote.
- If gametes are haploid, the zygote has two sets of chromosomes, so it is diploid (46 in humans).
- So the chromosome number stays the same in every generation instead of doubling.
- Meiosis produces gametes that are genetically different from each other.
- Each child develops from a different egg and a different sperm, fused at random, so each child has a different combination of alleles.
8 multiple-choice questions on this lesson
From the topic question bank. Assign them in the app for a marked score in your gradebook, or run the topic as a class game.
In which organ in a human male does meiosis take place?
- Atestis
- Bprostate gland
- Cpenis
- Dbladder
Which type of cell is produced by meiosis?
- Aan egg cell
- Ba zygote
- Ca skin cell
- Da root hair cell
Which process takes place when a human zygote divides to form an embryo?
- Amitosis
- Bmeiosis
- Cfertilisation
- Dpollination
A cat has 38 chromosomes in each body cell. How many chromosomes are in a cat egg cell and in a cat zygote?
- Aegg 19, zygote 38
- Begg 38, zygote 76
- Cegg 19, zygote 19
- Degg 38, zygote 38
Meiosis is described as a reduction division. What is reduced?
- Athe number of chromosomes, from diploid to haploid
- Bthe size of each chromosome, to half its length
- Cthe number of genes on each chromosome
- Dthe amount of cytoplasm in each gamete
Why are the gametes from one person genetically different from each other?
- AMeiosis gives each gamete a different mixture of chromosomes
- BMitosis copies the chromosomes with many mistakes
- CEach gamete receives both chromosomes of every pair
- DGametes are made from different parents
A cell with 6 chromosomes divides. Which result shows that the division was meiosis?
- A4 cells with 3 chromosomes each, all genetically different
- B2 cells with 6 chromosomes each, genetically identical
- C4 cells with 6 chromosomes each, genetically identical
- D2 cells with 12 chromosomes each, genetically different
Which statement about mitosis and meiosis in a human is correct?
- AMitosis gives diploid cells; meiosis gives haploid cells
- BMitosis gives haploid cells; meiosis gives diploid cells
- CBoth give genetically identical diploid cells
- DBoth give genetically different haploid cells
Quiz key
Sperm are made in the testes, and meiosis is the division involved in producing gametes. The prostate gland adds fluid to make semen but does not make sperm. The penis transfers semen. The bladder stores urine and is not part of gamete production.
Meiosis is involved in the production of gametes, such as egg cells. A zygote is formed when two gametes fuse at fertilisation, not by meiosis. Skin cells and root hair cells are body cells made by mitosis.
Growth of the embryo needs genetically identical cells with the full diploid number, so the zygote divides by mitosis. Meiosis only makes gametes. Fertilisation formed the zygote but is not division. Pollination is the transfer of pollen in flowering plants.
Meiosis halves the diploid number, so the egg has 38 / 2 = 19; an egg (19) and a sperm (19) fuse to give a diploid zygote with 38. An egg with 38 would make a zygote with 76, doubling the number each generation. A zygote with 19 forgets that two gametes fuse. Eggs are haploid, so they cannot have 38.
In meiosis the chromosome number is halved, from two sets (diploid) to one set (haploid). Each chromosome stays whole, so its length is not halved. Each chromosome still carries all of its genes. Cytoplasm is shared out in any cell division, so that is not what the term describes.
Meiosis gives each gamete one chromosome of each pair, and which one goes into each gamete varies, so the gametes carry different combinations of alleles. Gametes are made by meiosis, not mitosis, and mitosis copies chromosomes exactly. Gametes are haploid, so they receive only one chromosome of each pair. All of one person's gametes come from that same person.
Meiosis halves the chromosome number (6 to 3) and gives genetically different cells, four from each parent cell. Two identical cells with 6 chromosomes is the result of one mitosis, and four identical cells with 6 is mitosis twice. No division doubles the number to 12.
Mitosis keeps the chromosome number, so body cells stay diploid (46); meiosis halves it, giving haploid gametes (23). The second option reverses the two. Only mitosis gives identical diploid cells, and only meiosis gives different haploid cells, so neither statement about both is true.
What to project
The student lesson embeds these tabs. Open them full screen on the projector; every slider has a drag handle on the stage.
Slides for this lesson
A projectable deck for every pack is on the way. Until then, present the student lesson full screen: its sections, figure and lab tabs follow the same order as the plan above.