Question:
The homozygous Andalusian chicken exhibits black feathers (BB) and white feathers
(WW), while the heterozygous bird has bluish feathers.
(i) If two heterozygous Andalusian chickens are crossed, what are the possible
genotypic and phenotypic ratios of their offspring?
(ii) What kind of dominance does the gene for feather colour exhibit? Give a reason
to support your answer.
Answer:
Hi there!
Heterozygous birds (BW) show incomplete dominance with bluish feathers phenotype.
(i) Crossing two heterozygotes we get:
BW x BW = BB (Black) : BW (Bluish) : WW (White) in ratio 1:2:1
Here the genotypic ratio would be BB:BW:WW = 1:2:1
And phenotypic ratio would be Black: Bluish: White = 1:2:1
(ii) The gene for feather colour shows incomplete dominance, where allele B is unable to express itself completely in the presence of allele W giving an intermediate phenotype.
Thanks
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