Question

Punnett squares are used to show possible combinations of alleles or to predict the probability of a trait occurring in offspring. A parakeet that is heterozygous for blue feathers (dominant) is crossed with a parakeet that is homozygous for white feathers (recessive). mc022-1.jpg mc022-2.jpg According to the Punnett square for this cross, what percentage of offspring is predicted to have blue feathers?

Answer 1

A punnett square is a tabular summary of the possible combinations of the paternal and maternal alleles and thus predicting the genotypes of the organisms in a breeding experiment.

A parakeet that is heterozygous dominant with blue feathers can be represented by the genotype Bb. A parakeet that is homozygous recessive with white feathers can be represented by the genotype bb. When a cross is made between these two, the percentage of offspring predicted to have blue feathers is 50%. It can be represented below-

Phenotype -     Blue feathers    x     White feathers

Genotype  -          Bb                 x               bb

Punnett square                 B                          b

                         b              Bb                        bb

                         b              Bb                        bb

Thus, the percentage of offspring with blue feathers is 50% with a genotype Bb.

Answer 2

50% will have blue feathers