Question

An individual that is homozygous dominant for type B blood and little finger shape mates with an individual that is heterozygous for type A blood and homozygous recessive for little finger shape . what are the predicted genotypic and phenotypic ratios for the cross?

Answer 1

Answer:

Let "L" be the dominant allele for little finger shape and "l" be the recessive allele for the same.

It is given that a person is homozygous dominant for blood group B and little finger shape. Hence, the genotype would be $I^BI^B$LL

The other person is heterozygous for blood group A and homozygous recessive for little finger shape. Hence, the genotype would be $I^Aill$

The type of gametes formed by the first parent would be $I^BL$ only.

The type of gametes formed by second parent would be $I^Al$ and il.

The cross is shown in the attached figure.

According to the cross, we get two phenotype:

• offspring with blood group AB and dominant little finger shape, and
• offspring with blood group group B and dominant little finger shape.
• They are present in 4 : 4 = 1 : 1

According to the cross, we get two genotype:

• $I^AI^BLl$
• $I^BiLl$
• They are also present in 4 : 4 = 1 : 1.