Question

Two short-haired guinea pigs are mated several times. Out of 100 offspring, 25 of them have long hair. What are the probable genotypes of the parents? Show the Punnett Square to prove it.

Answer 1

Answer:

Ss (male) × Ss (female)

Explanation:

This question involves a single gene coding for hair length in guinea pigs. Based on the information in this question, the allele for short hair (S) is dominant over the allele for long hair (s). This means that a guinea pig will only be phenotypically long-haired if the genotype is "ss".

According to this question, Two short-haired guinea pigs are mated several times. Out of the 100 offsprings produced by this cross, 25 of them have long hair (recessive). This means that the phenotypic ratio of this cross is 3 short hair : 1 long hair i.e. 100 - 25 = 75 short hair. 75/25 = 3/1 = 3:1

To produce this phenotypic ratio, the parents must both be heterozygous (Ss) for the hair length gene.