To solve a Punnett square for a test cross involving two traits (assuming a dihybrid cross), we'll use the notation typically applied in genetics. Let's assume we're working with two traits:
- Trait 1 (e.g., fur color) with alleles B (dominant) and b (recessive).
- Trait 2 (e.g., eye color) with alleles E (dominant) and e (recessive).
In our case, one parent (let's say the male) is purebred for the dominant traits (BBEE), while the other parent (the female) is purebred for the recessive traits (bbee).
Therefore, the offspring genotype alignments will be as follows:
| | BE | BE | BE | BE |
| -------- | --- | --- | --- | --- |
| be | BbEe | BbEe | BbEe | BbEe |
| be | BbEe | BbEe | BbEe | BbEe |
| be | BbEe | BbEe | BbEe | BbEe |
| be | BbEe | BbEe | BbEe | BbEe |
Every box in the Punnett square shows the combination of one allele from each parent.
- The male parent contributes BE to every offspring.
- The female parent contributes be to every offspring.
Thus, each offspring inherits one B and one b, one E, and one e, making every offspring dihybrid (heterozygous) for both traits. The genotype for all the offspring is BbEe.
So, when we fill in the Punnett square:
1. Top-left to bottom-right diagonals all have the genotype BbEe.
2. This result is consistent throughout all the squares of the Punnett square.
Therefore, the possible genotypes for their offspring are all BbEe in every square.
