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The inheritance of blood group is determined by some allelic genes which are Iᴬ, Iᴮ & Iᴼ. In one individual two allelic genes are present. Iᴬ & Iᴮ are dominant while Iᴼ is recessive in heterozygous condition. So if a child has a blood group O he/she must have IᴼIᴼ & he/she cannot have the parents of blood group AB & AB/O.

1. In foetus; liver, spleen, bone marrow, lymph nodes & thymus are the haemopoietic organs (blood forming). In adults most of the blood corpuscles form in the peripheral region of red bone marrow in long bones.
2. Man (A): IᴬIᴼ → IᴬIᴬ → A → IᴬIᴮ → AB Woman (AB): IᴬIᴮ → IᴬIᴼ → AB → IᴮIᴼ → B OR IᴬIᴬ → IᴬIᴬ → A → IᴬIᴮ → AB all show homozygous
3. The genotype child of having O blood group is IᴼIᴼ If father has B blood group it is either – IᴮIᴮ or IᴮIᴼ but if father has IᴮIᴮ then child cannot have IᴼIᴼ, so father must have IᴮIᴼ.
4. Lymphocyte is a type of white blood cells in the vertebrate immune system. Lymphocytes are responsible for making antibodies.

Correct answer: The genotype child of having O blood group is IᴼIᴼ If father has B blood group it is either – IᴮIᴮ or IᴮIᴼ but if father has IᴮIᴮ then child cannot have IᴼIᴼ, so father must have IᴮIᴼ.

Solution

A child with blood group O must be genotype IᴼIᴼ, so each parent must contribute an Iᴼ allele. A B-phenotype parent could be IᴮIᴮ or IᴮIᴼ, but only IᴮIᴼ can pass Iᴼ, so that is the required genotype.

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