Describe spermatogenesis and oogenesis with flow charts.

1. 1 · Define. Gametogenesis is the formation of haploid gametes from diploid cells by meiosis.
2. 2 · Draw the spermatogenesis chart. [Flow chart: spermatogonium (2n) → primary spermatocyte (2n) → meiosis I → 2 secondary spermatocytes (n) → meiosis II → 4 spermatids (n) → 4 sperms]
3. 3 · Explain spermatogenesis.
   • In the seminiferous tubules, from puberty.
   • One primary spermatocyte gives four sperms.
   • Spermatids change into sperms (spermiogenesis).
4. 4 · Draw the oogenesis chart. [Flow chart: oogonium (2n) → primary oocyte (2n) → meiosis I → secondary oocyte (n) + polar body → meiosis II → ovum (n) + polar body]
5. 5 · Explain oogenesis.
   • In the ovary; it starts before birth.
   • Unequal divisions: the ovum keeps most of the cytoplasm.
   • One primary oocyte gives one ovum.
6. 6 · Link to daily life. A balanced diet and avoiding tobacco and alcohol keep gametes healthy.
7. 7 · Close. Both halve the chromosome number (46 to 23), so the zygote gets 46 again after fertilisation.

Scoring tip: Write 2n or n at every stage of the flow chart. That is what examiners check first.