You are studying body color in an African spider and have found that it is controlled by a single gene with four alleles: B (brown), br (red), bg (green), and by (yellow). B is dominant to all the other alleles, and by is recessive to all the other alleles. The bg allele is dominant to by but recessive to br. You cross a brown (B/by) spider with a pure-breeding green spider. Predict the phenotype of the progeny.

Explanation:

Given;

B allele is for brown color, so B = brown,

br= red,

bg= green,

by= yellow.

B is dominant over all;

bg is dominant over by;

br is dominant over bg;

by is recessive to all other alleles.

Here,  cross between  brown (B/by) and pure green (bg/bg).

B/by× bg/bg

progeny

Genotype= B/bg, B/bg, by/bg and by/bg.

Phenotype= B/bg= brown;

by/bg= green

So, 1/2 are brown and 1/2 are green.

it will be bbb bbb bbb bbb bbb bbb bbb bbb