A population consists of 9% white sheep and 91% black sheep. What is the frequency of the black wool allele if the black-wool allele is dominant and the white-wool allele is recessive?
A. 0.09
B. 0.3
C. 0.42
D. 0.7

Hint: In the genetics, in order to know whether the populations are evolving or not, and it is one of the way to know the allele frequency in the population, where there are two equations given by Weinberg to calculate the frequencies in the population.

Complete answer:
In the above question, they gave two types of traits that are black wool of sheep, and the white wool of the sheep.
And they gave that the black is dominant, and the white is recessive.
So assume that p= black wool of sheep= dominant allele
And q= white wool of the sheep = recessive allele
In the question the percentage that was given are,
P= 91%, and q= 9%.
It can be calculated as q2 = 9%.
Which mean that $q_{2}$= $\dfrac{9}{100}$= 0.09
Where q= $\sqrt{0.09}$ = 0.3.
It gives the frequency of the recessive allele that is 0.3.
And the frequency of the dominant can be calculated by the Hardy Weinberg formula, where it states that an allele or genotype frequency of the population is generally constant or remains the same unless there is any evolutionary influence in the population.
The formula of hardy Weinberg is p + q = 1
Where we know that the frequency of the q= 0.03, so that, p + 0.3 = 1.
Which means p = 1- 0.3 = 0.7.
So the frequency of the black wool from the above given question is 0.7.
So, the correct answer is “Option D”.

Note: There are five conditions where the population is In the hardy Weinberg equilibrium where if population met those 5 conditions then one can say those populations are in equilibrium and not evolving, they are Random mating, large population, and no natural selection, no mutation and no migration.