Question

"Pegasus is one of the best-known creatures in Greek mythology that is part horse and part bird. A cross between a blue female Pegasus and a white male Pegasus produces offspring that are silver. The color of a Pegasus is determined by two alleles, HB for blue and HW for white.

a. What type of inheritance is this an example of?
b. If a heterozygous female mates with a heterozygous male, what are the genotypes of the parents?
c. Predict the genotypic and phenotypic ratios that would result from a cross between these two parents."

A) Incomplete dominance; Genotypes: HBHB (female) and HBHW (male)
B) Co-dominance; Genotypes: HBHB (female) and HBHW (male)
C) Complete dominance; Genotypes: HBHB (female) and HBHW (male)
D) Recessive inheritance; Genotypes: HBHB (female) and HBHW (male)

Answer 1

The inheritance pattern is incomplete dominance, with heterozygous parent genotypes of HBHW. Crossing two heterozygous parents results in a 1 blue: 2 silver: 1 white ratio for both genotypic and phenotypic offspring.

Step-by-step explanation:

The coloration of the offspring suggests that we are observing incomplete dominance in this genetic scenario. This mode of inheritance results in offspring with a phenotype that is intermediate between the two parent phenotypes. Because a cross between a blue Pegasus and a white Pegasus results in a silver Pegasus, neither color is completely dominant over the other.

For part b, if both parents are blue and white (heterozygous), their genotypes would each be HBHW.

To determine the predicted genotypic and phenotypic ratios, we need to perform a cross using a Punnett square:

• HBHW (female) x HBHW (male)

In the Punnett square, we would fill in the potential genotypes:

• 1 HBHB (blue)
• 2 HBHW (silver, the heterozygous phenotype)
• 1 HWHW (white)

The genotypic ratio from this cross would be 1 blue: 2 silver: 1 white, and the phenotypic ratio would also be 1:2:1 reflecting the respective colors.