Final answer:
The genotype bbee will produce yellow-coated offspring when mated with a yellow lab also of genotype bbee, as the recessive ee genotype is epistatic and masks the expression of the B gene.
Step-by-step explanation:
In the context of Labrador retriever coat color genetics, the genotype which will produce offspring with yellow coats when mated with a yellow lab with genotype bbee is bbee. The homozygous recessive ee genotype is epistatic to any combination of alleles at the B gene. In the absence of a dominant E allele, coat color is yellow regardless of the B genotype. If a dominant E allele is present, a B allele results in a black coat, whereas the homozygous bb genotype results in a brown coat.In this case, the genotype that would produce offspring with yellow coats (all of them) when mated with a yellow lab with genotype bbee is bbee.
To provide further clarification, the gene E must be present in a dominant form (E) to have any effect on the coat color produced by the B gene. With two recessive e alleles, as in the genotype bbee, the dog will have a yellow coat, making the B gene's influence on coat color irrelevant. Because epistasis occurs where one gene (the E gene) masks the effect of another gene (the B gene), a dog with any genotype containing ee will display the yellow coat phenotype, regardless of the B alleles present.