Final answer:
When a black cat is crossed with a white cat and black is co-dominant to white, 100% of the offspring will be black-and-white because the progeny will be heterozygous, displaying both alleles.
Step-by-step explanation:
The question involves predicting the phenotypes of the offspring when a black cat is crossed with a white cat, given that black (B) is co-dominant to white (W). In the case of co-dominance, both alleles are expressed in the phenotype. When a black cat is crossed with a white cat, the resulting offspring will all be black-and-white. This is because black is co-dominant to white, meaning both traits are expressed fully in the offspring. Therefore, the percentage of black-and-white offspring will be 100%.
Therefore, when a black cat (homozygous BB) is crossed with a white cat (homozygous WW), all offspring will be heterozygous (BW) and display a black-and-white pattern. As a result, 100% of the offspring will be black-and-white.