ICSE Class 10Biology
⏱️ 14 min readGenetics – Heredity and Variation
Mendel's Laws: Law of Segregation, Law of Independent Assortment, Law of Dominance.; Sex-linked inheritance: Haemophilia and colour blindness are X-linked recessive traits (males are far more vulnerable).
⚡ Essential Formula / LawCore Syllabus Rule
Monohybrid Phenotypic Ratio = 3:1 | Genotypic = 1:2:1 | Dihybrid Phenotypic = 9:3:3:1
🎯 High-Yield Syllabus Checkpoints
- 1Mendel's Laws: Law of Segregation, Law of Independent Assortment, Law of Dominance.
- 2Sex-linked inheritance: Haemophilia and colour blindness are X-linked recessive traits (males are far more vulnerable).
- 3Punnett square calculation and genotype versus phenotype distinction.
🚨 Examiner Traps & Common Mistakes
⚠️ Common Student Pitfall
Inheriting colour blindness from father to son (father passes Y chromosome to son; mutation is carried on the X chromosome from mother).
⚠️ Common Student Pitfall
Writing phenotypic ratio when genotypic ratio was explicitly requested.
📚 Verified Technical Definitions
Allele
Alternative forms of a gene occupying the same locus on a homologous chromosome and controlling contrasting traits.
Phenotype
The observable physical, biochemical, or anatomical expression of an organism determined by its genotype.
Spaced Repetition Protocol:
Day 1Day 3Day 7Day 21