CIE iGCSE Biology-17.3 Meiosis- Study Notes- New Syllabus
CIE iGCSE Biology-17.3 Meiosis- Study Notes – New syllabus
CIE iGCSE Biology-17.3 Meiosis- Study Notes -CIE iGCSE Biology – per latest Syllabus.
Key Concepts:
Supplement
- State that meiosis is involved in the production of gametes
- Describe meiosis as a reduction division in which the chromosome number is halved from diploid to haploid resulting in genetically different cells (details of the stages of meiosis are not required)
Role of Meiosis in Gamete Production
Key Statement:
Meiosis is the type of cell division involved in the production of gametes (sex cells).
📘 Explanation:
- Gametes are sperm in males and egg cells in females.
- These cells need to have half the number of chromosomes so that when they fuse during fertilisation, the full set is restored.
- Meiosis reduces the chromosome number by half, producing haploid cells from a diploid parent cell
🔢 In Humans:
| Cell Type | Chromosome Number |
|---|---|
| Body cell (diploid) | 46 |
| Gamete (haploid) | 23 |
🧠 Summary:
Meiosis ensures that gametes contain the correct number of chromosomes, which is essential for maintaining the species’ chromosome number during sexual reproduction.
Meiosis ensures that gametes contain the correct number of chromosomes, which is essential for maintaining the species’ chromosome number during sexual reproduction.
What is Meiosis?
Key Definition:
Meiosis is a type of reduction division in which the chromosome number is halved from diploid (2n) to haploid (n), resulting in genetically different cells.
📘 Explanation:
- Meiosis occurs in reproductive organs to form gametes (sperm and egg).
- The parent cell has two sets of chromosomes (diploid), but the gametes formed have only one set (haploid).
- This is necessary so that when fertilisation occurs, the resulting zygote has the correct diploid number.
🌱 Key Features of Meiosis:
| Feature | Description |
|---|---|
| Chromosome number | Halved from diploid (2n) to haploid (n) |
| Cell division | Involves two divisions, forming 4 cells from 1 |
| Genetic variation | Each gamete is genetically different |
| Purpose | To produce gametes for sexual reproduction |
🧪 In Humans:
- Diploid body cell: 46 chromosomes
- Haploid gamete: 23 chromosomes
- Fertilisation: 23 + 23 = 46 (restoring diploid number)
🧠 Summary Line:
Meiosis ensures that gametes have half the chromosome number and are genetically diverse, which is essential for variation in offspring.
Meiosis ensures that gametes have half the chromosome number and are genetically diverse, which is essential for variation in offspring.