In a population of dogs, fur color is determined by two alleles: black (B) and tan (b). The black allele shows complete dominance. If a dog has tan fur, what is its genotype?

Rationale

The genotype of a dog with tan fur is bb.

In this scenario, the black allele (B) is dominant over the tan allele (b). Therefore, a dog exhibiting tan fur must possess two copies of the tan allele, resulting in the homozygous recessive genotype of bb.

A (BB) YOUR ANSWER

The genotype BB indicates a dog that has two dominant black alleles. Such a dog would express black fur rather than tan, as the presence of the dominant allele would mask any recessive traits.

B (Bb) YOUR ANSWER

A Bb genotype consists of one black allele and one tan allele. This configuration would also result in a black-furred dog, as the black allele is dominant and will overshadow the recessive tan allele.

C (bb) CORRECT

This genotype signifies that the dog has two recessive alleles for fur color. Since tan fur is only expressed in the absence of dominant alleles, a dog with the bb genotype will display tan fur, which is consistent with the question's premise.

D (Not enough information) YOUR ANSWER

While one might assume more information is needed in complex genetic cases, the dominance relationship between the alleles clarifies that a dog with tan fur must possess the bb genotype. The dominance of allele B over allele b provides adequate information to ascertain the tan fur phenotype.

Conclusion

In genetic terms, the phenotype of tan fur in this dog population unequivocally indicates a homozygous recessive genotype of bb, given the complete dominance of the black allele. The presence of tan fur rules out any dominant alleles, confirming that the only possible genotype for a tan-furred dog is bb. Understanding this relationship between alleles is essential in predicting phenotypic outcomes in genetic breeding scenarios.

In a population of dogs, fur color is determined by two alleles: black (B) and tan (b). The black allele shows complete dominance. If a dog has tan fur, what is its genotype?

The genotype of a dog with tan fur is bb.

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