Q3 Page 147 - Chapter 9 Class 10 - Heredity and Evolution

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

Answer:

The information is not sufficient to conclude which is the dominant and recessive trait.

• The genotype and the genotypic ratio is required to determine if the emergent trait is dominant or recessive.
• The genotypes using which blood group is denoted are as follows:

But according to blood heredity, the Blood type A allele is always dominant and the allele for Blood type O is always recessive .

• From the chart, blood group A can be denoted as I ^A I ^A or I ^A l where I A is the dominant trait and i is the recessive trait.
• Blood group O is denoted by ii (recessive allele).