Eye color in humans is determined by a gene pair with the gene for brown eyes B
ID: 3262193 • Letter: E
Question
Eye color in humans is determined by a gene pair with the gene for brown eyes B being dominant over the gene for blue eyes b. Therefore, a person will have brown eyes if he or she is of type BB or Bb, and will have blue eyes only if he or she is of type bb. If the first child of a brown-eyed man and a brown-eyed woman has blue eyes, a) What is the probability that their second child will have brown eyes? b) If this second child has brown eyes and marries someone with blue eyes, what is the probability that a child of their will have brown eyes?Explanation / Answer
as first child of brown eyed pair has blue eyes; mean each of them has a Bb gtype,
a)as there are total 4 outcome for a child gene of Bb type ={BB,bB,Bb,bb}
out of these four , three have dominant Brown gene
therefore probabilty that their second children will have brown eyes =(3/4)
b)probability that child of theirs will have brown eyes =probabilty that second child has BB genes and his child has brown eyes second child has Bb genes and his child has browm eyes =(1/4)*(1)+(2/4)*(1/2)=1/2
therefore probabilty that a child of theirs will have brown child; given second child has brown eyes
=(1/2)/(3/4)=2/3
please revert for any clarification needed.
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