The homozygous condition HbsHbsresults in sickle cell anaemia whereas HbAHbs has the sickling trait. What is the probability that a couple with the sickling trait will give birth to one normal child?
1/2
1/4
1/8
none
Explanation
Video Explanation
No video available
Post your Contribution
Discussions (25)
U will get AA, AS, AS SS . so d probability z number of required out come/ number of possible out come. nu of req outc = 1 (AA)(normal). nu of poss outc =4 (AA, AS, AS, SS). ; 1÷4= 1/4.
ANSWER IS (A) OUTCOME IS AS, AS, SS, SS NORMAL IS 2 DIVIDED BY 4 WHICH IS 1/2
The problem here is lack of ability comprehend. The question said HbA and HbS is the sickling trait. it then proceeded to state the fact that the parents possess the sickling trait. So it's a cross between two heterozygous i.e AS and AS. The result give AA AS AS ans SS so the probability is 1/4
Making the Answer B
they are correct,if you read and understand the question well , what they said was that Hbs was the condition while HbAHbs was a trait
NOTE : they didn't say HBsHBs and HBaHBs where the parents
when you read it you will see they said the parents have the trait
this means both the parents are HBaHBs
hence,
NORMAL=1/4
CARRIER =1/4
SICKLER =1/2
since both parents have the sickling trait HbA HbS then both parents are heterozygous so now
the cross is simply going to be between the two heterozygous parents i.e
HbA HbS x HbA HbS
the possible 4 combinations in their offspring are:
1) HbA HbA (normal)
2) HbA HbS (sickle cell trait)
3) HbS HbA (sickle cell trait)
4) HbS HbS (sickle cell anemia)
and from the above we can see that only one (1) out of the (4) combinations resulted in a normal child so the answer would be 1/4 making option B correct 
The ans might be A.
They asked for the probability of the couple with AS (NOT BOTH). For that couple it's a 50/50 change if he/she gives out A allele
The ans is A bcos the parents are the ones wiyh the sickling trait the homozygous sickle cell was a decoy the main idea was the sickle cell trait of the parent which when combines gives AA,AS,AS,SS. The SS is the condition that is said to be created if the AS gametes meet.
