Question

In sheep, white vs yellow body fat is determined by a single pair of autosomal alleles. In a large, randomly mating flock, 23 percent of the sheep have white fat and 77 percent have yellow fat. You may conclude from this data that:
a. The allele for yellow is dominant to white
b. The allele for white is dominant to yellow
c. The alleles for yellow and white are codominant
d. The alleles for white and yellow are in a Hardy-Weinberg equilibrium
e. None of the above are valid conclusions

Answer 1

Answer:

Option A , The allele for yellow is dominant to white

Explanation:

It is given that 23 percent of the sheep have white fat and 77 percent have yellow fat.

Thus, it is clear that sheeps with yellow fat is a dominant characteristics.

Usually, the frequency of homozygous recessive allele in a given population is represented by  $q^2$

and here $q^2 = 0.23$

Frequency of allele for white fat $= q = \sqrt{0.23} \\q= 0.479$

While frequency of homozygous dominant allele and heterozygous dominant allele is represented by $p^2+2pq$

And here $p^2+2pq = 0.77$

Allele for yellow fat $= 1-q\\= 1-0.479\\= 0.521$

Hence, option A is correct.