IGNOU LSE 3 2026 - In a randomly mating laboratory population of Drosophila, 4 per cent o

Question

In a randomly mating laboratory population of Drosophila, 4 per cent of the flies have black bodies (black is autosomal recessive, b) and 96 per cent have brown bodies (normal colour, B). If this population is assumed to be in Hardy-Weinberg equilibrium, what are the allelic frequencies of B and b, and the genotypic frequencies of BB and Bb?

28 Jan 2026

Answer :

Word Count : 383

In a population where the black body colour in Drosophila is controlled by an autosomal recessive allele (b), and brown is dominant (B), the Hardy-Weinberg principle can be applied to estimate allelic and genotypic frequencies. Let (q) represent the frequency of the recessive allele (b) and (p) represent the frequency of the dominant allele (B). According to Hardy-Weinberg equilibrium, the frequency of the homozygous recessive genotype (bb) is equal to (q^2). It is given that 4% of the flies have black bodies, which corresponds to the homozygous recessive genotype (bb). Therefore, (q^2 = 0.04). Taking the square root of both sides, we get (q = \sqrt{0.04} = 0.2). Since (p + q = 1) in a two-allele system, the frequency of the dominant allele (B) is

__________ _____ _____ ________ ___ __________ _____ ______ ____ _________ ________.
_________ _______ _______ ____ _________ _________ _____ ___ __________.
_____ _____ ____ ________ _______ _____ ________ _________ _____ _____ _________ ________.
______ _______ ______ _____ ________.
____ ____ _________ ________ _________ __________ ____.
___ _____ _________ _____ _________ _________ __________ _____ ______ ________.
_____ ________ _________ ____ ______.
_________ _______ ________ ___ __________ ________ __________ _____.
__________ _________ __________ ____ ___ _____ _____ ____ ________ ____ ___.
_________ _____ ______ ________ ___ _________ ___ _______ ________.
____ _______ _______ ___ __________ ___ _______ ______ ___ ________.
______ ____ _______ _______ _____ ___ _______ ________.
_____ ______ ____ _______ ___.
________ ____ ________ ____ ____ ________ ______ ____ ___.
_________ __________ _______ ___ ______ _______ _____ ______ ________ ___ __________.
_____ _________ _______ ________ ______.
_____ __________ _____ _______ ______ ______ ____ __________ ________ _______.
________ _____ ______ ______ ______ ___ __________.
___ __________ _______ ________ _____.
__________ _______ ____ ________ _____ _______ _______ ______ _____.
_____ ___ _______ _______ _____.
________ __________ _____ _______ __________ ________ ________.
_____ _______ ______ _____ ____ ______ _____ ________.
______ _________ _________ __________ __________ ____ ____ _________ __________ __________ ____ _________.
_______ ________ _________ _______ ___ ___ _________.
____ ___ ___ _____ ____ _______ _____ ________ ______ _____ __________ ____.
________ __________ ________ ____ _________ ____ __________ ____ _______ _________.
__________ ___ ______ _________ ____ _______ __________ ___.
_______ _____ ____ ______ _____ ____.
_________ __________ _____ __________ ______ _____ ______.
______ _____ _____ _______ _________ _____ ____ ______ ________.

IGNOU ACADEMY

Your IGNOU journey, made easier.

Solved Assignments
Study Notes
Guess Papers
Question Papers

Call Us WhatsApp

STUDY • PREPARE • SUCCEED

Skip in 10