Question

In Drosophila cross, the heterozygous member with grey body (b⁺) and long wings (vg⁺) was crossed with black body and vestigial wings, the progeny had the following ratio; grey vestigial 24: grey long 126: black long 26: black vestigial 124. What is the frequency of recombinants in the population?

• A. 15.8 %
• B. 16.7 %
• C. 17.5 %
• D. 14.5 %

Answer 1

Answer: (B)

P₁ = grey and long
P₂ = black and vestigial
Their recombination results in grey vestigial and black long variants.
Total population: 300
Recombinant population (26 grey vestigial + 24 black long): 50
$FrequencyofRecombination=\frac{Totalnumberofrecombinantsx100}{Totalnumberofindividuals(population)}Therefore,wehaveFrequencyofRecombination=\frac{50(totalrecombinants)x100}{300(totalofpopulation)}$
Frequency of recombinants in the population: 50/300 × 100 = 16.7 %