Question

Generation 1: 2 families that live right next door to each other both own a female long hair cat and a male short hair cat. In each house, the two cats mate and have kittens.

Generation 2: All of the kittens in both houses have long hair. Another neighbor decides to adopt a kitten from each family. The neighbor adopts a male kitten from one house and a female kitten from another house.
Generation 3: These kittens grow and mate and have kittens of their own. In this litter of kittens, some have short hair and some have long hair.

Explain which trait is dominant and which trait is recessive. Use your knowledge of genetics to explain in detail how you know which trait is dominant and which trait is recessive. Include vocabulary words such as trait, gene and allele.

Answer 1

In the breeding scenario of cats, the long hair trait is dominant, as it appears in all second-generation kittens even when one parent is short-haired. The short hair trait is recessive, evidenced by its emergence in the third generation after two long-haired cats, carrying the recessive allele, produced offspring with both traits.

Step-by-step explanation:

To explain which trait is dominant and which trait is recessive, we can look at the given scenario involving the breeding of cats. A trait refers to a specific characteristic, such as fur length, that is genetically determined. A gene is a segment of DNA that controls the inheritance of traits, and each gene can have different forms called alleles.

In the scenario, all Generation 2 kittens have long hair, despite the parents having one long hair and one short hair cat, which implies that the long hair trait is dominant over the short hair trait. Since all offspring exhibit the long hair trait, it suggests that long hair is governed by a dominant allele which we can denote as 'L'. Similarly, the short hair trait appears to be recessive because it only shows up in Generation 3 after two long hair cats mate and have some short hair offspring, indicating that they were carriers of the recessive allele, denoted as 'l'. Furthermore, in the third generation, the appearance of both long hair and short hair kittens indicates that the allele for short hair (l) had been carried by both parents heterozygously (Ll), and upon mating, some of their offspring inherited two recessive alleles (ll), thereby expressing the recessive short hair trait.