In a population of guinea pigs, short hair is dominant to long hair. if 25 percent of a breeder’s guinea pigs has long hair, what is the frequency of the recessive allele (q)?
5 percent
15 percent
25 percent
50 percent

If 25 percent of a breeder’s guinea pigs has long hair, the frequency of the recessive allele (q) is 50%. Let A be dominant allele and a be recessive allele. The frequencies are as following: p - the frequency of dominant allele, q - the frequency of recessive allele, p^2 - the frequency of genotype AA (short hair), 2pq - the frequency of genotype Aa (short hair), and q^2 - the frequency of genotype aa (long hair). So, we know that q^2 = 25% = 0.25. We need to find q. q = √q^2 = √0.25 = 0.50 = 50%.