Final answer:
A cross between a chihuahua with a genotype Bb Ss and another with bb ss results in a 1:1:1:1 phenotypic ratio, yielding equal chances of having offspring with the phenotypes black and solid, black and spotted, red and solid, and red and spotted.
Step-by-step explanation:
The question involves a cross between two chihuahuas, one with a genotype of Bb Ss and the other with bb ss. In this genetic cross, black coat color (B) is dominant over red (b), and solid color (S) is dominant over spotted (s). To determine the phenotypic ratio, we consider the possible combinations of these alleles.The Bb dog can produce gametes with alleles B or b, and S or s. The bb ss dog can only produce gametes with alleles b and s. When these gametes combine, we can have offspring with the following genotypes: Bb Ss, Bb ss, bb Ss, and bb ss. These correspond to the following phenotypes:
- Bb Ss - black and solid
- Bb ss - black and spotted
- bb Ss - red and solid
- bb ss - red and spotted
Each of these combinations has an equal chance of occurring since we are doing a cross with heterozygotes, hence there is a 1:1:1:1 phenotypic ratio for the offspring.In summary, a cross of Bb Ss with bb ss would produce the phenotypic ratio of 1 black and solid : 1 black and spotted : 1 red and solid : 1 red and spotted.