Question

In a certain animal black fur b is dominant to white fur

b. determine the expected genotypic ratios and phenotypic ratios resulting from a cross between

Answer 1

The genotypic ratios and phenotypic ratios resulting from a cross between two heterozygotes (Bb) of black fur (B) being dominant to white fur (b) can be determined using a Punnett square. The genotypic ratio would be 1:2:1, while the phenotypic ratio would be 3:1.

Step-by-step explanation:

In the scenario provided, where black fur (b) is dominant to white fur, we can determine the expected genotypic and phenotypic ratios resulting from a cross, assuming we are crossing two heterozygous individuals (Bb x Bb). When crossing two heterozygous organisms, each parent can pass on either the dominant or the recessive allele with equal probability.

The Punnett square method can be used to visualize the genetic crosses and predict the ratios of genotypes and phenotypes. With each parent being heterozygous (Bb), the Punnett square would look like this:

• BB (black fur)
• Bb (black fur)
• Bb (black fur)
• bb (white fur)

The genotypic ratio in the offspring would be 1 BB: 2 Bb: 1 bb. This reflects one homozygous dominant, two heterozygous, and one homozygous recessive individuals.

For the phenotypic ratio, because black fur is dominant to white fur, the ratio of black to white offspring would be 3:1, with three-quarters showing the dominant phenotype (black fur) and one-quarter showing the recessive phenotype (white fur).

Answer 2

In the f1 generation the animals will have black fur.
In the f2 generation the animals will have both black and white fur.
The genotypic ratio is 3:1
The phenotypic ratio is 1:2:1