Question

In some bees, thin stripes (S) are dominant over thick stripes (s) and black eyes (B) are dominant over gray eyes (b). Complete a dihybrid cross for parents with the genotypes: SsBB × ssBb and answer the following in complete sentences.

Describe how you would set up a Punnett square for this cross.
List the likelihood of each possible offspring genotype.
List the likelihood of each possible offspring phenotype.

Answer 1

you first need to compute the gamete formations for each parent: e.g. SsBB will give 50% SB and 50% sB;
then you make a table with columns being filled with gametes from the father and lines with gametes from mother. adding the alleles from the line and column gives you the genotype; then you deduce the phenotype.