In guinea pigs, hair colour and hair length are determined by two genes located on different chromosomes.

Hair colour is determined by a gene with two alleles:

• Allele $B$ is dominant and results in black hair.
• Allele $b$ is recessive and results in brown hair.

Hair length is determined by a gene with two alleles:

• Allele $S$ is dominant and results in short hair.
• Allele $s$ is recessive and results in long hair.

Two guinea pigs are crossed:

• One parent has black, short hair and is heterozygous for both genes.
• The other parent has brown, short hair and is heterozygous for the hair length gene.

Complete the following details to show this genetic cross: