How this Chapter is Tested in NEET
Principles of Inheritance and Variation is one of the most reliably tested chapters in the whole NEET Biology paper - expect several questions every year, a mix of direct recall and short problem-solving.
The recurring favourites are:
- Mendel's laws and crosses - monohybrid and dihybrid ratios (3:1, 9:3:3:1), the test cross, and the Law of Segregation vs Independent Assortment.
- Departures from dominance - incomplete dominance (snapdragon pink), co-dominance and multiple alleles (ABO blood groups), pleiotropy and polygenic inheritance.
- Chromosomal theory and linkage - Sutton & Boveri (proposed) vs Morgan (verified), Sturtevant and map units (centimorgan), recombination.
- Sex determination - XX-XY, XX-XO (grasshopper) and ZZ-ZW (birds), and who is heterogametic.
- Genetic disorders - haemophilia and colour blindness (X-linked recessive), sickle-cell (Glu -> Val) and thalassaemia (qualitative vs quantitative), phenylketonuria; and the chromosomal disorders Down's (47, trisomy 21), Klinefelter's (XXY) and Turner's (X0).
The set below combines genuine NEET previous-year questions with a few exam-pattern questions in the same style. Several are short calculations - practise setting up the cross rather than guessing.
Strategy: for any cross question, first write down the genotypes, then list the gametes (2^n rule), and only then combine them; for a disorder, recall its inheritance pattern (autosomal/X-linked, dominant/recessive) and, if chromosomal, its chromosome number.