1.1 Farmer Brown has a breed of white-feathered chickens that is homozygous for the dominant allele A which produces coloured feathers. These chickens are also homozygous for the dominant allele B for another independently assorting gene which inhibits colouration of the feathers. Farmer MacDonald has a different breed of white chickens that are homozygous recessive for both the A/a and B/b genes. One of farmer Brown’s hens (AABB) is crossed with one of farmer MacDonald’s roosters (aabb) to generate the F1 generation. What are the expected F2 phenotypes and proportions from the crossing the F1 offspring?
1.1 Farmer Brown has a breed of white-feathered chickens that is homozygous for the dominant allele A which produces coloured feathers. These chickens are also homozygous for the dominant allele B for another independently assorting gene which inhibits colouration of the feathers. Farmer MacDonald has a different breed of white chickens that are homozygous recessive for both the A/a and B/b genes. One of farmer Brown’s hens (AABB) is crossed with one of farmer MacDonald’s roosters (aabb) to generate the F1 generation. What are the expected F2
1.2 A certain animal can have brown, red, black or gray fur. Assume that fur colour is controlled by a single gene with multiple alleles in a dominance series where black (B1) > brown (B2) > red (B3) > gray (B4). Give the genotypes of two phenotypically different heterozygotes that when crossed produce offspring with the phenotypic ratio of 1 black : 1 brown.
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