Question

Hi, there are two parts to the question and it is bolded

You are in charge of the national Unicorn breeding program. Unicorns can have either swirled or solid horns with the swirled (Sw) phenotype being dominant over solid (sw). Their fur can be gold (F+), bronze (fb), silver (fs) or white (fw), with the colour alleles following a dominance series of: F+ > fb > fs > fw

Which pair could you mate to potentially get some offspring with silver fur and swirled horns?

Select one:

a. A bronze and swirled horned unicorn with a white and solid horned unicorn

b. A true breeding gold and swirled horned unicorn with a true breeding white and solid horned unicorn

c. A silver and solid horned unicorn with a silver and solid horned unicorn

You mate a silver fur, solid horned unicorn, whose mother had white fur and a swirled horn, with a white fur, solid horned unicorn whose mother had gold fur and a solid horn. What is the probability that the offspring will have white fur (with any type of horn)?

Select one:

a. 1/3

b. 1/4

c. 1/16

d. 1/2

Answer 1

1) a) A bronze and swirled horned unicorn with a white and solid horned unicorn

genotype of bronze and swirled horned unicorn can be Swswfbfs and genotype of white, solid horned unicorn is swswfwfw, these parents can have progeny with swirled horn and silver fur

b. A true breeding gold and swirled horned unicorn with a true breeding white and solid horned unicorn

genotype of true breeding gold and swirled horned unicorn is fgfgSwSw and genotype of  true breeding white and solid horned unicorn fwfwswsw, both of these parents lack fs allele so they cannot have progeny with swirled horn and silver fur.

c. A silver and solid horned unicorn with a silver and solid horned unicorn

silver and solid horned unicorn can be fsfsswsw and genotype of silver and solid horned unicorn is fsfsswsw

since both of these parents lacks Sw allele they cannot have progeny with progeny with swirled horn and silver fur.

so the answer is a) A bronze and swirled horned unicorn with a white and solid horned unicorn.

2) genotype of the silver fur, solid horned unicorn, whose mother had white fur and a swirled horn is fsfwswsw and genotype of unicorn with white fur, and solid horn is fwfwswsw

fsfwswsw * fwfwswsw

	fssw	fwsw
fwsw	fsfwswsw ( silver fur, solid horn)	fwfwswsw ( white fur, solid horn)
fwsw	fsfwswsw ( silver fur, solid horn)	fwfwswsw ( ( white fur, solid horn)

probability that the offspring will have white fur = number of progeny with white fur/total number=2/4=1/2

so the answer is d) 1/2