The 9:3:3:1 ratio of law of independent assortment can be affected by
Correct answer: C. Gene linkage
- A. Genetic drift
- B. Small population
- C. Gene linkage
- D. Gene duplication
Explanation
Independent assortment requires the two genes to be on different chromosomes, so genes linked on the same chromosome travel together and the dihybrid ratio departs from 9:3:3:1, with parental combinations over represented. Genetic drift and small population size shift allele frequencies across generations rather than distorting the ratio within a single cross. Crossing over partly restores the expected ratio by separating linked genes.
This question appeared on the UHS MDCAT 2025 paper, which you can sit online with every answer explained.
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About Gene Linkage and Crossing Over
Linked genes lie on the same chromosome and tend to pass together, unlike genes that assort independently on different chromosomes. The topic connects linkage with homologous pairing, crossing over during prophase I of meiosis, recombinant and parental offspring, and recombination frequency as an estimate of gene distance.
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