Final answer:
Using a Punnett square for a cross between two heterozygous guinea pigs (Bb), it is determined that three out of four offspring are expected to have black hair due to the dominance of the 'B' allele, while one will have white hair, displaying a 3:1 phenotypic ratio.
Step-by-step explanation:
The question involves determining the hair color of guinea pig offspring using a Punnett square. In guinea pigs, black hair color is represented by the dominant allele 'B' and white hair color by the recessive allele 'b'. A Punnett square showing the cross between two heterozygous guinea pigs (Bb) indicates the possible genetic combinations they can produce.
To predict the offspring's hair color, we follow these steps using a Punnett square:
- Place the alleles from one parent across the top (B and b).
- Place the alleles from the other parent along the left side (B and b).
- Fill in the squares by combining the top and side alleles to represent the offspring's genotype.
The resulting genotypes are: one BB, two Bb, and one bb. Since 'B' is dominant over 'b', any offspring with at least one 'B' allele will have black hair. Thus, three of the four offspring (BB and both Bb) would have black hair, while one (bb) would have white hair. This result illustrates a typical 3:1 phenotypic ratio for a monohybrid cross involving simple dominance.