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Science-Related Homework Help High School Level Science Topic started by: RADIOhead on Jul 25, 2011



Title: Black feathers are dominant over white feathers. Black hen mated with a black rooster...
Post by: RADIOhead on Jul 25, 2011
black feathers are dominant over white feathers. black hen mated with a black rooster. 42 chicks hatched. 31=black 11 white. gene formulas for the two parents and their offspring are.
a. P1=Bb x bb; F1 genotypes: Bb, bb, Bb, bb
d. P1= Bb x Bb; F1genotypes: BB, bb, Bb

now im uncertain between the two. i know a= 50% and d=25%
so that would make d the correct answer


Title: Black feathers are dominant over white feathers. Black hen mated with a black rooster...
Post by: biolove on Jul 25, 2011
It's (D) has to be :D


Title: Black feathers are dominant over white feathers. Black hen mated with a black rooster...
Post by: Bio_World100 on Aug 1, 2011
The question states that black feathers are dominant over white feathers.  This questions deals with simple Mendelian inheritance, in particular a monohybrid cross.  

A black hen is mated with a white rooster and the result was 31 black and 11 white.  

So, let's define our alleles:

B = black (dominant)
b = white (recessive)

So, the genotypes in the cross will be as follows:

Bb x Bb (both parents must be heterozygous since the recessive trait appears in the F1 generation).  If one of the parents were to be homozygous dominant, then the offspring will all be black: 1/2 Bb and 1/2 BB.  The question says there were 11 WHITE in the F1 generation.  If both of the parents were homozygous dominant, the F1 generation would still be all black.  So, the only combination of the two parents that fits with your results are: Bb x Bb.

So, the answer is D

Hope that helps!   :)