Final answer:
The phenotypic outcomes of crossing two heterozygous speckled chickens are 25% black, 50% speckled, and 25% white, due to the Mendelian inheritance of heterozygous alleles.
Step-by-step explanation:
When crossing two heterozygous speckled chickens, which we can represent as Bb (where 'B' is the allele for black color and 'b' is the allele for white color), the possible phenotypic outcomes are derived from a Punnett square analysis. Assuming speckled is a result of heterozygosity (Bb), the Punnett square would show that 25% of the offspring would be 'BB' (black), 50% would be 'Bb' (speckled), and 25% would be 'bb' (white).
Therefore, the phenotypic outcomes for the offspring of two heterozygous speckled chickens are 25% black, 50% speckled, and 25% white. These outcomes are based on the foundational principles of Mendelian genetics and the inheritance of alleles. Each parent can contribute one of the two alleles they possess, leading to a variety of combinations in their offspring.