AP BIOLOGY

Detailed explanation-1: -Phenotypic ratio for a monohybrid cross is 3 : 1; thus total 2 types of genotypes can be formed; option C is incorrect for a dihybrid cross. Phenotypic ratio for a trihybrid cross is 27 : 9 : 9 : 9 : 3 : 3 : 3 : 1; thus total 8 types of genotypes can be formed; option A is incorrect for a dihybrid cross.

Detailed explanation-2: -Since there are three different alleles, six different genotypes are possible.

Detailed explanation-3: -For the F2 generation of a monohybrid cross, the following three possible combinations of genotypes result: homozygous dominant, heterozygous, or homozygous recessive.

Detailed explanation-4: -The number of genotypes in dihybrid test cross are 4. The number of phenotypes in dihybrid test cross are also 4.

Detailed explanation-5: -For a monohybrid cross of two true-breeding parents, each parent contributes one type of allele. In this case, only one genotype is possible.