Question

We have a population of snakes. They are either all black or black with red stripes.

We make the following crosses to help us determine the gene interaction:

A cross between the solid black snakes and the striped snakes results in a 1:1 ratio of solid black to striped snakes among the offspring.

A cross between two striped snakes results in progeny in the ratio of 2 striped for every 1 solid black.

Assume that these outcomes are manifested by genetic differences that occur at only one bi-allelic locus.

Then, from these results, we can determine the mode(s) of gene interaction. Please indicate what the mode(s) is/are by selecting from the list below.

		Pleiotropy
		Codominance
		Complete dominance
		I couldn't find this question posted anywhere on the internet, so I can't figure it out.
		Incomplete dominance
		Recessive lethality

Answer 1

Codominance

Recessive lethality

Explanation:

Solid black = BB

Black with red stripes =Bb

Red = bb (lethal)

solid black snakes (BB) X striped snakes (Bb)---Parents

	B	b
B	BB(black)	Bb (striped)

A cross between two striped snakes results in progeny in the ratio of 2 striped for every 1 solid black.

Striped snakes (Bb) x (striped snakes(Bb)----Parents

	B	b
B	BB(black)	Bb(striped)
b	Bb(striped)	bb (red-lethal)

Striped (2) : Solid black (1)