Question

According to the Punnett square: B represents the dominant gene for blue feathers and b represents the recessive gene for red feathers. Two heterozygous birds have one offspring. What percent chance does it have for red feathers?

Answer 1

25% chance

Step-by-step explanation:

This is a monohybrid cross involving one gene coding for feather colour in birds. The allele for blue feather (B) is dominant over the allele for red feather (b). This means that Allele B will mask the expression of allele b in a heterozygous state, making the blue color to be expressed according to Mendel's law of dominance.

In a heterozygous state i.e. different form of the gene (allele) combined together, (Bb), the different alleles will segregate equally into gametes according to Mendel's law of segregation. These gametes will form the basis of the punnet square (as seen in the attached image).

According to the cross as depicted using the punnet square, four possible offsprings will be produced, with the following genotypes: BB, Bb, Bb, bb.

The BB (homozygous dominant) offspring will be phenotypically blue feathered

The 2 Bb (heterozygous) will be phenotypically blue feathered, because the dominant allele blue.

The bb (homozygous recessive) will be red feathered. N.B: a recessive trait will only be expressed in an homozygous state.

Therefore, the percentage chance that the offspring will be red-feathered is 1/4 × 100 = 25%.