Recurring NEET Themes (in order of frequency)

Theme 1 — Ratio Calculations (highest frequency) NEET asks students to: predict F2 ratios from given parental cross, calculate number of offspring of a specific phenotype, identify what ratio confirms independent assortment vs linkage. Know: 3:1 (monohybrid), 9:3:3:1 (dihybrid), 1:2:1 (incomplete/co-dominance), and all five modified ratios.

Theme 2 — ABO Blood Group Logic NEET tests: identifying offspring blood groups from parental genotypes, identifying impossible offspring, deducing parental genotype from offspring groups. Key rule: AB × O → only A and B offspring. AB × AB → A, AB, B (no O). Any cross where one parent is O (ii) → all children receive one i allele.

Theme 3 — Distinguishing Dominance Patterns NEET provides examples and asks for the type: blended F1 = incomplete dominance (snapdragon); both phenotypes in F1 = co-dominance (ABO AB); all F1 dominant = complete dominance. The distinction between incomplete dominance and co-dominance is tested with multiple-choice distractors.

Theme 4 — Pleiotropy vs Polygenic (definition-based) NEET uses reversed definitions as distractors. Remember: Pleiotropy = 1→many; Polygenic = many→1. Sickle cell = pleiotropy (one HbS allele, multiple effects). Skin colour = polygenic (many genes, continuous trait).

Theme 5 — Linked Genes and Independent Assortment Exception NEET asks: which law is violated by linked genes? Answer: Law of Independent Assortment. Who demonstrated linkage? Morgan, using Drosophila. What is recombination frequency used for? Measuring genetic distance (in cM).

One-Line NEET Answer Templates

• "This is an example of ___" → know the definition that matches the example
• "What ratio would be obtained?" → identify cross type, dominance pattern, then apply ratio
• "What is impossible among offspring?" → work backwards from genotype rules
• "Who proposed?" → Mendel (laws), Sutton+Boveri (chromosomal theory), Morgan (linkage)