Question

In rabbits, black hair depends on a dominant allele, b, and brown hair on a recessive allele, b. Short hair is due to a dominant allele, s, and long hair to a recessive allele, s. If a true-breeding black short-haired male is mated with a brown long-haired female, describe their offspring. What will be the genotypes of the offspring? If two of these F1 rabbits are mated, what phenotypes would you expect among their offspring? In what proportions?

Answer 1

A true-breeding black short-haired male mated with a brown long-haired female will produce all black short-haired heterozygous offspring. When these offspring mate, the phenotypes of their offspring will exhibit a 9:3:3:1 ratio in the F2 generation according to Mendelian inheritance patterns.

Step-by-step explanation:

In rabbits, the allele for black hair (b) is dominant and the allele for brown hair (b) is recessive. Similarly, the allele for short hair (s) is dominant over the allele for long hair (s). A true-breeding black short-haired male rabbit, with the genotype BbSs, mated with a brown long-haired female rabbit (bbss), will produce offspring that are all heterozygous black and short-haired with a genotype of BbsS. If two of these F1 offspring were mated (BbsS X BbsS), the expected phenotypic ratio among their offspring in the F2 generation would be 9:3:3:1 , with 9 having black and short hair, 3 having black and long hair, 3 having brown and short hair, and 1 having brown and long hair.

This is an example of a dihybrid cross, where two independent traits are considered. The Punnett Square method can help visualize the possible combinations of alleles from both parents and predict the phenotypic ratios of the offspring. Due to independent assortment, the genotypes and phenotypes are distributed according to the Mendelian inheritance pattern.