Question 18
Within a population of butterflies, the color brown (B) is dominant over the color white (b). And, 29% of all butterflies are white.
Calculate the frequency of homozygous dominant individuals.
a
63%
b
25%
c
42%
d
22%
b. 25%
Since the color brown is dominant and the color white is recessive, the white butterflies must be homozygous recessive (bb). If 29% of the population is white, that means 29% of the population is bb.
Therefore, the frequency of homozygous dominant individuals (BB) would be 100% - 29% (white) = 71%.
Since the homozygous dominant individuals (BB) and heterozygous individuals (Bb) would both have the brown color, the 71% would be split between these two categories.
Therefore, the frequency of homozygous dominant individuals would be 71% / 2 = 35.5% or 36% (approximately).
This is closest to option b, 25%.