To complete a Punnett square for the parents with the genotypes bb and bb, we start by setting up a 2×2 grid, since each parent can contribute one allele to the offspring.
1. **Set up the Punnett Square:** Write the alleles of one parent along the top of the grid and the alleles of the other parent along the left side. In this case, both parents have the genotype ‘bb’, which means both contribute a ‘b’ allele.
2. **Fill in the grid:** Place the alleles in the boxes. Since both parents can only pass on ‘b’, all four boxes will be filled with ‘bb’.
| b | b | |
|---|---|---|
| b | bb | bb |
| b | bb | bb |
3. **Analyze the results:** In this case, all potential offspring will have the genotype ‘bb’. This means that 100% of the offspring will express the same trait governed by the ‘b’ allele.
In summary, completing the Punnett square for two parents with the genotype ‘bb’ shows that all offspring will also have the genotype ‘bb’, highlighting the traits are completely homozygous recessive in this scenario.