Frequency of Question Types (Estimated Annual Pattern)
| Topic | Approximate Frequency | Question Type |
|---|---|---|
| Monohybrid/Dihybrid ratio calculations | 1–2 questions/year | Numerical, Punnett square |
| ABO blood group genetics | 1 question/year | Cross calculation, genotype identification |
| Incomplete vs Co-dominance distinction | 1 question/year | Definition, example identification |
| Mendel's 7 traits — which is dominant | 0.5/year | One-liner recall |
| Pleiotropy vs Polygenic distinction | 0.5–1/year | Definition, example matching |
| Modified dihybrid ratios (9:7, 12:3:1, etc.) | 0.5/year | Ratio identification, gene interaction type |
| Chromosomal Theory (Sutton, Boveri, Morgan) | 0.5/year | Historical fact, experimental organism |
High-Yield PYQ Patterns
- Cross i × i: Always produces A, B, AB, O in 1:1:1:1. NEET has asked the number of possible blood groups and probability of each group.
- Snapdragons (Rr × Rr): Produces 1:2:1 ratio. NEET has asked for the F2 ratio and whether this demonstrates co-dominance or incomplete dominance.
- Tt × tt test cross: NEET has asked to identify genotype of parent from 1:1 or all-dominant offspring ratios.
- Sickle cell/HbS = pleiotropy: NEET has directly asked "what type of inheritance is sickle cell anemia" with polygenic as a distractor.
- Morgan's Drosophila: Linked gene demonstration. NEET has asked which law was violated and who demonstrated it.
- Modified ratios: NEET has presented 9:7 or 13:3 and asked to identify gene interaction type.
Common Wrong-Answer Choices
- "Incomplete dominance" when "co-dominance" is the answer (or vice versa) — always check if phenotype is blended or dual
- "Polygenic" when "pleiotropic" is correct — read carefully if one gene or many genes are involved
- "9:3:3:1" for a dihybrid cross with gene interaction — identify if interaction is stated
- "Back cross" when "test cross" is meant — check if tester is homozygous recessive
Exam Strategy
- Always check: Are genes on the same or different chromosomes?
- When in doubt about dominance type: F1 phenotype that is intermediate → incomplete; F1 shows both phenotypes → co-dominance; F1 shows only one parent's phenotype → complete dominance.
- For blood group problems: draw the Punnett square explicitly — this eliminates all errors.