Edexcel iGCSE Biology-4.32 Diploid vs Haploid- Study Notes- New Syllabus
Edexcel iGCSE Biology-4.32 Diploid vs Haploid- Study Notes- New syllabus
Edexcel iGCSE Biology-4.32 Diploid vs Haploid- Study Notes -Edexcel iGCSE Biology – per latest Syllabus.
Key Concepts:
4.32 know that in human cells the diploid number of chromosomes is 46 and the haploid number is 23
Chromosome Numbers in Humans
🔹 Introduction
Humans have chromosomes in pairs in each cell.
Diploid (2n) = full set in body cells.
Haploid (n) = half set in gametes (sperm & egg).
📌 Key Points
- Diploid number (2n) = 46 → Found in somatic (body) cells
- 23 pairs: 22 pairs autosomes, 1 pair sex chromosomes (XX or XY)
- Haploid number (n) = 23 → Found in gametes (sperm & egg)
- Contains one chromosome from each pair
- During fertilisation: Haploid sperm (n=23) + Haploid egg (n=23) → Diploid zygote (2n=46)
📊 Summary Table
| Type of Cell | Chromosome Number | Example |
|---|---|---|
| Diploid (2n) | 46 | Body cells |
| Haploid (n) | 23 | Sperm, Egg |
📝 Quick Recap
Humans: 2n = 46 (body cells), n = 23 (gametes).
Fertilisation restores diploid number: 23 + 23 = 46.
23 pairs → 22 autosomes + 1 sex chromosome pair.