Biology · Variation and Genetics
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A man of blood group A marries a woman of blood group B and they have one child. Which one of the following statements about the child’s blood is correct?
- A
It could be group A only.
- B
It could be group AB only.
- C
It could be group A or group B only.
- D
It could be any of the groups A, B, AB and O.
ABO blood group in humans is controlled by three different alleles IA, IB and i. While the dominant alleles (IA and IB) code for the antigens A and B, respectively, i allele (which is recessive to both IA and IB) does not code for any antigen. The blood group of the man is A, which means the possible genotypes are IAIA or IAi. Likewise, the blood group of the woman is B, which means the possible genotypes are IBIB or IBi.
Therefore, A, B, AB, and O are the possible blood groups of offspring when a man with blood group A marries a woman with blood group B.
Diagram:
https://www.quora.com/Is-it-possible-for-parents-with-O-positive-and-B-positive-blood-give-birth-to-a-child-with-A-negative-blood-If-not-why
This option suggests that the child's blood group can only be A. However, this is not correct because when a person with blood group A (genotype AO) and a person with blood group B (genotype BO) have a child, the child can inherit one of the following blood groups: A (genotype AO), B (genotype BO), AB (genotype AB), or O (genotype OO). So, Option A is incorrect.
This option suggests that the child's blood group can only be AB. Again, this is incorrect because, as mentioned earlier, the child can inherit one of four possible blood groups: A, B, AB, or O. So, Option B is incorrect.
This option proposes that the child's blood group can only be A or B. However, this is also not correct, as explained before. The child can have any of the four blood groups: A, B, AB, or O. So, Option C is incorrect.
ABO blood group in humans is controlled by three different alleles IA, IB and i. While the dominant alleles (IA and IB) code for the antigens A and B, respectively, i allele (which is recessive to both IA and IB) does not code for any antigen. The blood group of the man is A, which means the possible genotypes are IAIA or IAi. Likewise, the blood group of the woman is B, which means the possible genotypes are IBIB or IBi.
Therefore, A, B, AB, and O are the possible blood groups of offspring when a man with blood group A marries a woman with blood group B.
Tagged under Biology · Variation and Genetics · 2022