Which genotype would not be present in the offspring from a SsYy x ssyy test cross?

To understand why SsYY would not be present in the offspring from a cross between SsYy (heterozygous for both traits) and ssyy (homozygous recessive for both traits), we need to consider the genetic contributions from each parent.

In this test cross, the parent with the genotype SsYy can contribute either a dominant or recessive allele for each trait. This results in the following gametes: SY, Sy, sY, and sy. The second parent, ssyy, can only contribute the recessive alleles sy.

When we look at the potential combinations of alleles from these gametes, we can construct a Punnett square to visualize the possible genotypes in the offspring:

• From SsYy (producing gametes SY, Sy, sY, sy) and ssyy (producing gamete sy), the possible combinations become:

• Sy (from SsYy) + sy = Ssyy (heterozygous for the first trait, homozygous recessive for the second)

• sy (from SsYy) + sy = ssyy (homozygous recessive for both traits)

• SY (from SsY