Question

If a husband has blood group O and wife blood group AB, the blood group of the child cannot be
A. A
B. B
C. AB only
D. O or AB

Answer 1

Hint: Karl Landsteiner discovered the ABO blood group mechanism. The legacy of the blood group depends on the phenomenon of domination, recession, and codominance. The alleles can be dominant or recessive, for the blood group A and B.

Complete answer:
The progeny could not be O in the situation given in the question. It is due to the phenomenon recognized as dominance. One of the genes is dominant over the other allele in accordance with the Law of superiority and is known as the dominant allele. The other is recognized as the recessive allele. The dominant personality is displayed if a pair of genes is homozygous to the dominant allele. If the gene pair is homozygous to the recessive alleles, then the recessive personality is revealed. On the other hand, the character will be heterozygous for that gene mixture when both predominant and recessive alleles are present. In this case, it is only the dominant characteristics that are expressed. The heterozygous allele in a gene couple is some other interesting phenomenon, and each allele is expressed entirely. This phenomenon is recognized as codominance.
Here, \[{{I}^{A}}{{I}^{B}}\]-Father’s phenotype
           \[{{I}^{O}}{{I}^{O}}\]- Mother’s phenotype
The alleles of blood group A and blood group B is dominant and blood group O is recessive.

	\[{{I}^{O}}\]	\[{{I}^{O}}\]
\[{{I}^{A}}\]	\[{{I}^{A}}\]\[{{I}^{O}}\]	\[{{I}^{A}}\]\[{{I}^{O}}\]
\[{{I}^{B~~}}~\]	\[{{I}^{B~~}}~\]\[{{I}^{O}}\]	\[{{I}^{B~~}}~\]\[{{I}^{O}}\]

	\[A\]	\[B\]	\[AB\]	\[O\]
\[AB\]	\[A,\text{ }B,\text{ }OR\text{ }AB\]	\[A,\text{ }B,\text{ }OR\text{ }AB\]	\[A,\text{ }B,\text{ }OR\text{ }AB\]	\[A\text{ }or\text{ }O\]
\[O\]	\[A\text{ }or\text{ }O\]	\[B\text{ }or\text{ }O\]	\[A\text{ }or\text{ }B\]	\[O\]

Note:
The Rh (rhesus) type decides the blood group positively or negatively apart from the ABO blood team system. Rh antigen indicates a tremendous blood team (Rh-positive) and the absence of Rh suggests a bad blood group (Rh-negative).