In a dihybrid cross of SsYy x SsYy, how many different genotypes are homozygous for both traits?

In a dihybrid cross of individuals with genotypes SsYy, where "S" and "s" represent alleles for one trait and "Y" and "y" represent alleles for another trait, we can analyze the combinations that result from the cross.

There are four possible gametes produced from each parent: SY, Sy, sY, and sy. When these gametes combine, they can form various genotypes in the offspring. To determine how many different genotypes are homozygous for both traits, we need to identify the combinations of alleles that are homozygous (having two identical alleles) for each trait.

For the "S" trait, the homozygous genotypes are SS and ss. For the "Y" trait, the homozygous genotypes are YY and yy. To form a genotype that is homozygous for both traits, we can combine the homozygous forms as follows:

1. SSYY - homozygous dominant for both traits

2. SSyy - homozygous for the first trait (SS) and homozygous recessive for the second trait (yy)

3. ssYY - homozygous recessive for the first trait (ss)