AP BIOLOGY

Detailed explanation-1: -If the results of a test cross reveal that all the offspring resemble the parent being tested. This parent must be homozygous because all the gametes of parents carry the same allele that fuses to form same offsprings. Thus, the correct answer is option B.

Detailed explanation-2: -If all the offspring have the dominant trait, the unknown genotype is homozygous dominant.

Detailed explanation-3: -An organism with two dominant alleles for a trait is said to have a homozygous dominant genotype.

Detailed explanation-4: -If the test cross results in any recessive offspring, then the parent organism is heterozygous for the allele in question. If the test cross results in only phenotypically dominant offspring, then the parent organism is homozygous dominant for the allele in question.

Detailed explanation-5: -Two-Gene Test Crosses Test crosses operate under the same principle no matter whether you are considering one gene or multiple genes; in all cases, you are crossing an individual of a dominant phenotype but unknown genotype to an individual that is homozygous recessive for all relevant genes.