A woman gives birth to a son who has type O blood. She has type B blood. Which of the following can be concluded from this about her parents' blood types?
First of all, her genotype is not BB because she gave birth to a son with type O blood which requires two 'O' alleles (one from each parent). This indicates that her blood genotype is BO (phenotype B). Therefore she must have inherited a B allele from one parent and an O allele from the other. Therefore, her parents genotypes must of been either, AB and BO <--- that's phenotypes AB and B BO and BO <--- that's phenotypes B and B AO and BO <--- that's phenotypes A and B AA and BO AO and BB etc. etc. The punnett squares illustrates the first two. Also note, that the BO x BO combination has 1/2 a chance of passing on the BO genotype. Whereas the ABxBO combination has only 1/4 of a chance of passing on the BO genotype. Therefore, it would be logical to conclude that her parents genotypes were most likely BO and BO. |dw:1374128276736:dw|
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