Questions
7–9 questions per NEET/CUET paper
Difficulty
Medium-Hard
Importance
High-yield core unit for all medical and biology-based entrance exams
Overview
Genetics and Evolution is the cornerstone of modern biology, bridging Mendelian inheritance with molecular data and evolutionary dynamics. It is a high-yield unit for NEET, CUET, and boards, requiring a strong grasp of numerical pedigree analysis, protein synthesis pathways, and population genetics.
Mendelian Genetics & Extensions
Mendelian principles provide the foundation for inheritance, but entrance exams focus heavily on deviations like codominance, incomplete dominance, and multiple alleles. Mastering dihybrid crosses and pedigree analysis is essential for solving complex lineage-based questions.
- Law of Segregation: alleles separate during gamete formation
- Law of Independent Assortment: 9:3:3:1 phenotypic ratio
- Incomplete dominance ratio: 1:2:1
- Test cross: used to determine the zygosity of an individual
- Pleiotropy: one gene influencing multiple phenotypic traits
Molecular Basis of Inheritance
This section covers the central dogma from replication to translation. Focus on the chemical nature of DNA, the mechanisms of transcription, and the intricate process of protein synthesis, as these are frequently tested via conceptual statements and flowcharts.
- DNA replication is semi-conservative (Meselson-Stahl experiment)
- Transcription: promoter, structural gene, and terminator
- Genetic code is degenerate, unambiguous, and universal
- Translation: activation of amino acids and peptide bond formation
- Operon model: lac operon (negative inducible system)
Evolution and Hardy-Weinberg Equilibrium
Evolutionary biology examines natural selection, genetic drift, and the mathematical framework of population genetics. The Hardy-Weinberg law is the most critical numerical application in this unit.
- Hardy-Weinberg equilibrium: p^2 + 2pq + q^2 = 1
- Five factors affecting HWE: Mutation, Gene flow, Genetic drift, Recombination, Natural selection
- Adaptive radiation: Darwin's finches
- Convergent vs Divergent evolution examples
- Bottleneck and Founder effect
Formula Sheet
p + q = 1
p^2 + 2pq + q^2 = 1
Recombination frequency = (Number of recombinants / Total progeny) * 100
Number of genotypes = n(n+1)/2 (for multiple alleles)
Exam Tip
When solving pedigree charts, always rule out Y-linked or X-linked inheritance patterns first by checking if the trait skips a generation or is present in all offspring of affected parents.
Common Mistakes
- Confusing linkage/recombination frequency with actual distance in map units for non-linked genes.
- Miscalculating Hardy-Weinberg frequencies by forgetting to take the square root of the homozygous recessive frequency (q^2).
- Overlooking the difference between transcription start sites in prokaryotes versus eukaryotes.
More Revision Notes
Ready to test yourself?
Play topic-wise Genetics & Evolution questions in Aspirant Arcade — gamified MCQ practice.
Download Free