Question

Fill a Punnett Square with the offspring expected when crossing bb x Bb, and find what the genotype and phenotype ratio are.

Answer 1

The genotype ratio of the offspring is 1:1 (Bb: bb), and the phenotype ratio is also 1:1.

Step-by-step explanation:

To create a Punnett square for the cross between bb and Bb, you would place the factors B and b from the second parent at the top of the square, and the factors b from the first parent on the left side of the square. Pull the factors from the top (B and b) into the boxes below, and pull the factor from the side (b) into the box next to it. The possible offspring are represented by the letters in the boxes: Bb, bb. Therefore, the genotype ratio is 1:1 (Bb: bb). The phenotype ratio is also 1:1, as they both have the same trait of having a blue eye color.

Answer 2

To fill the Punnett Square we must place the alleles from one of the parents (Bb) horizontally oriented on the top of a 3x3 diagram, and the alleles from the other parent (bb) vertically oriented on the left border of the diagram. After that, we must cross each one of the alleles from one parent with the alleles of the other, positioning the result of those crossings (Bb or bb) in the blank space where those alleles meet, as follows:

Therefore, 2/4 (or 1/2) of the offspring will be heterozygous (Bb) and 2/4 (or 1/2) of the offspring will be recessive homozygous (bb). The genotype ratio is 1:1 (one heterozygous for each recessive homozygous. The phenotype ratio is 1:1 (one organism with a dominant phenotype - Bb - for each organism with a recessive phenotype - bb).