Question

1. In goldfish, golden scales is a dominant trait. Use G to represent the dominant trait and g to represent the recessive trait of white scales. Predict the outcome of a cross between a heterozygous golden scale fish and a white scaled fish. What phenotype ratios will the offspring have?

2. In ostriches, incomplete dominance is shown in beak color. The beak colors are red, yellow, and orange. Orange is a phenotype of the red and yellow allele combination. What is the expected phenotypic outcome of mating a yellow and orange beaked bird?


3.One pair of genes for coat color in cats is sex-linked and shows incomplete dominance. Gene Y produces yellow coats and is located in the X chromosome (XY ). Gene B produces a black coat (XB). Heterozygous (XB XY) produces a tortoise shell coat.

Why will there never be any tortoise shell males and What kind of offspring will result from mating a yellow male and a black female?

Answer 1

1.

G - dominant trait (golden)

g - recessive trait (white)

Heterozygous - Gg

White (homozygous recessive) - gg

P: Gg x gg

(picture 1)

Genotype: 50% Gg 50% gg

Phenotype: 50% golden 50% white

2.

R - dominant (red)

r - recessive (yellow)

RR - red

rr - yellow

Rr - orange

P: rr x Rr

(picture 2)

Genotype: 50% Rr 50% rr

Phenotype: 50% orange 50% yellow