A certain herd of horses contains black horses and brown horses. These horses are diploid...
A certain herd of horses contains black horses and brown horses. These horses are diploid organisms, and coat color is an autosomal trait. The gene for a brown coat (B) is completely dominant, while the gene for a black coat (b) is recessive. Assume that the population is in Hardy-Weinberg Equilibrium. If prevalence of the R allele in the herd of horses is 0.6, what is the prevalence of black horses in the herd?
- A. 0.8
- B. 0.4
- C. 0.18
- D. 0.16
Correct Answer: D. 0.16
Explanation
This is a Hardy-Weinberg Equilibrium problem. The question stem gives you the prevalence of the dominant allele, 0.6. The prevalence of the dominant allele and the prevalence of the recessive allele must always add together to equal 1: p+q=1 So, the prevalence of the recessive allele must be 0.4: p=0.6 p+q=10.6+q=11?0.6=0.4 The prevalence of the recessive phenotype is equal to the prevalence of the recessive allele squared: q2=0.42=0.16 In this case, black coat color is a recessive trait, so the prevalence of this recessive phenotype is equal to the prevalence of the recessive allele squared, or 0.16.