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A man with the blood type A and Rh+ marries a woman with A and Rh- blood-type. They have two boys who both have O- blood. Assuming simple Mendelian inheritance of blood type and Rh, what is the probability that their next two children will be male and will have O- blood, too?
A. 1/8
B. 1/16
C. 1/32
D. 1/64
E. 1/256
 

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Can someone please explain, what determines if the Kids get the O + or O - genotype ? I mean which one is dominant ? I thought the blood group is co dominant genetics :confused:
 

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Ive read about it online:
ABO system: A and B are dominant (3 alleles A,B and O)
So to be blood gp A, u can be AA or AO for example

Rh system: controlled by two genes: one is dominant and makes the person Rh+

The answer i came up with is 1/16 for their next kid to be male, O-
The question asks for the chance their "two" next kids to be O-. I thought that we multiply the chances of each kid, so 1/16 * 1/16.. But it doesn't give the answer..

That was my try .. Not sure if its correct
 

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1/2 chance of having son x 1/4 chance of son being blood group O x 2/4 chance of being rh negative x by same data for another child = 4/1024=1/256
 
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P(male)=1/2
Quest says two male thus 1/2*1/2=1/4(independent)
P(blood group-O)=1/4(punnett)
P(rh negative)=1/2
Thus 1/2*1/4*1/4=1/32:eek:
 
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