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An Andalusian fowl, with the heterozygous condition of alleles for black plumage B and white b is blue coloured. A blue Andalusian fowl is bred to a black Andulasian fowl, the proportion of the offspring will be:
BiologyPrinciples of Inheritance and VariationNEET
Options:
  • A 50 % white : 50 % blue
  • B 50 % black : 50 % blue
  • C 50 % black : 50 % white
  • D 25 % black : 25 % blue : 50 % white
Solution:
2616 Upvotes Verified Answer
The correct answer is: 50 % black : 50 % blue
Incomplete dominance is a deviation of Mendels law of dominance where the heterozygous individual instead of expressing the dominant trait, it expresses a trait which is a mix of the parent traits. On crossing, black form fowl with white form fowl, the offspring is blue form.

When a black form fowl is crossed with blue form fowl we get-
 
  B B
B BB
(Black)
BB
(Black)
b Bb
(Blue)
Bb
(Blue)

Genotype of F1 - BB and Bb  1:1
Phenotype of F1 - Black and Blue  1:1 50% black and 50% blue.

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