AP BIOLOGY

Detailed explanation-1: -The cross of an organism with an unknown dominant genotype with an organism that is homozygous recessive for that trait is called as test cross. If any of the offspring from a test cross have the recessive trait, the genotype of the parent with the dominant trait must be heterozygous.

Detailed explanation-2: -The test cross is another fundamental tool devised by Gregor Mendel. In its simplest form, a test cross is an experimental cross of an individual organism of dominant phenotype but unknown genotype and an organism with a homozygous recessive genotype (and phenotype).

Detailed explanation-3: -A test cross involves mating an unknown genotypic individual with a known homozygous recessive. This is because recessive alleles will always be masked by the presence of dominant alleles. Hence the phenotype of any offspring will reflect the genotype of the unknown parent.

Detailed explanation-4: -In a testcross, the parent that is homozygous recessive for the genes being studied is called the testcross parent. The parent that has the dominant phenotype of the genes being studied is called the non-testcross parent.

Detailed explanation-5: -A test cross is an experiment that is used to find out the genotype of a dominant plant of the F2 generation. It is performed by crossing the dominant offspring with the homozygous recessive parent. A tall plant (unknown genotype) is crossed with a dwarf plant (known genotype).