Andalusian chickens are one of the hundreds of different varieties of chickens.
ID: 139774 • Letter: A
Question
Andalusian chickens are one of the hundreds of different varieties of chickens. ( Sometime, see Feathersite.com for photographs of many more varieties of Gallus gallus.) Andalusians chickens come in 3 color varieties: black, white, and blue (so-called 'blues' are actually gray). The Black Andalusians are known to be homozygous at this color locus. We’ll symbolize their genotype with: A1A1. The White Andalusian are known to be homozyogous at this color locus. We’ll symbolize their genotype with: A2A2. When a Black and White are bred, all the members of their F1 are blue. What would be the predicted phenotypic ratio?
a. 1:1 (50% blue: 50% black)
b. 1:1 (50% blue: 50% white)
c. 1:2:1 (25% white: 50% blue: 25% black)
d. 2:1 (75% blue: 25% black)
Explanation / Answer
If you are crossing two parents that are 'true breeding.
Black=A1A1
White= A2A2
F1 generation is A1A2 ( blue)
This is incomplete dominance
The phenotypic ratio is 1:2:1
25% white: 50% blue :25% black( using punett square)
Answer is c
A1A1A1A1 A1A1A2A2 A1A1A2A2 A2A2A2A2