To complete the Punnett square, let's analyze the genotypes of the parents and what is already given.
The rows and columns of the Punnett square represent the possible gametes (alleles) from each parent.
In this case:
- The column headers represent the alleles from one parent (let's assume they're Bb) and the row headers represent the alleles from the other parent (let's assume they're also Bb).
The current portions of the Punnett square you provided are:
B b
B | BB ??
b | Bb bb
To determine what goes in the "??" cell, we need to identify which genotype can match with the given structure of the Punnett square.
The possible offspring from the cross between two Bb (heterozygous) parents are:
- BB (homozygous dominant)
- Bb (heterozygous)
- Bb (heterozygous)
- bb (homozygous recessive)
From the setup, we see:
- B x B results in BB
- B x b results in Bb
- b x B results in Bb
- b x b results in bb
The empty cell labeled "??" represents the result of a cross of "B" (from the first parent column) with "b" (from the second parent row). Hence, "B" combined with "b" will yield Bb.
Therefore, the answer to fill the "??" cell is:
D. Bb