Q75 of 167 Page 195

A man with blood group A marries a woman with blood group 0 and their daughter has blood group 0. Is this information enough to tell you which of the traits - blood group A or 0 -is dominant? Why or why not?

Case 1: Man with blood group A married a woman with blood group B. Blood group for man can be expressed by dominant genotype IAIA orIAIO and blood group O for woman is expressed by recessive genotype IOIO. The daughter will have O blood group type as a result of this IOIO inheritance of recessive traits from mother and father.

Case 2: Blood group A in father if has recessive genotype IAIA and mother has dominant genotype IAIO or IOIO. The daughter will have O blood type as a result of inheritance of dominant allele IO from mother and recessive allele IA from father.


Blood group A is expressed in both homozygous and heterozygous condition but Blood group O is expressed in recessive condition.


More from this chapter

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73

What are the possible blood groups likely to be inherited by children born to a group A mother and a group B father? Explain your reasoning.

 74

A couple with a newborn baby is troubled that the child does not resemble either of them. Suspecting that a mix-up occurred at the hospital, they check the blood type of the infant. It is type 0. Because the father is type A and the mother type B, they conclude that a mix-up has definitely occurred. Are they correct? Give reason for your answer

 76

A Mendelian experiment consisted of breeding tall TT pea plants bearing violet flowers with short t pea plants bearing white w flowers. The progeny all bore violet W flowers, but almost half of them were short. This suggested that the genetic make-up (or genotype) of the tall parent can be depicted as:

(a) TTWW


(b) TTww


(c) TtWW


(d) TtWw


Give reason for your choice

 77

A person first crossed pure-bred pea plants having round-yellow seeds with pure-bred pea plants having wrinkled-green seeds and found that only A-B type of seeds were produced in the F1generation. When F1 generation pea plants having A-B type of seeds were cross-bred by self-pollination, then in addition to the original round-yellow and wrinkled-green seeds, two new varieties A-D and C-B type of seeds were also obtained.

(a) What are A-B type of seeds?


(b) State whether A and B are dominant traits or recessive traits.


(c) What are A-D type of seeds?


(d) What are C-B type of seeds?


(e) Out of A-B and A-D types of seeds, which one will be produced in


(i) minimum numbers, and


(ii) maximum numbers, in the F2 generation ?