Question

Dihybrid Crosses: In guinea pigs, black coat colour (B) is dominant over white (b), and short hair length (H) is dominant over long (h). Indicate the genotypes and phenotypes from the following crosses: PLEASE HELP!! I am so confused! :'(

Answer 1

a) A Guinea pig that is homozygous for black and heterozygous for short hair is crossed with a white, long-haired guinea pig.

Homozygous - same copy of the gene.

One guinea pig is homozygous for black (BB). Since white hair is recessive, that means a white-haired guinea pig is homozygous for white (bb).



(BB) x (bb) = 100% (Bb)

So all offspring will have the black hair phenotype because black is dominant and white is recessive.