IP Biology Notes: Inheritance (Upper Sec 14)
26 Nov 2025, 00:00 Z
Reviewed by
Ezekiel Tan·Academic Advisor (Biology)
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Use this as a free IP Biology notes chapter on inheritance for Year 3 to Year 4. It keeps the IP pacing while reinforcing the 6093 biology foundations most schools test through DBQs, diagrams, and practical explanations.
Status: SEAB O-Level Biology 6093 syllabus (exams from 2026) checked 2025-11-30 - scope unchanged; remains the reference for this note.
What you must know
- Gene is a DNA segment; allele is an alternative form. Dominant masks recessive; codominant both expressed. Homozygous = same alleles; heterozygous = different alleles. Phenotype = observable traits; genotype = allele pair.
- Monohybrid crosses: use Punnett squares; F2 ratio 3:1 for heterozygous cross; test cross gives 1:1 if heterozygous. Deviations from chance due to small sample or linkage (beyond syllabus detail).
- ABO blood group: multiple alleles ();
