Question

A Mendelian test cross is used to determine whether?

1) an allele is dominant or recessive
2) flowers are purple or white
3) the genotype or phenotype is more important
4) an individual is homozygous or heterozygous
5) segregation or independent assortment is occurring

Answer 1

A Mendelian test cross is utilized to determine if an organism with a dominant phenotype is homozygous or heterozygous for that trait, based on the phenotypes of the offspring when crossed with a homozygous recessive individual.

Step-by-step explanation:

A Mendelian test cross is used to determine whether an individual is homozygous or heterozygous for a dominant trait. During a test cross, an organism with the dominant phenotype that may either be homozygous dominant (AA) or heterozygous (Aa) is crossed with an organism that is homozygous recessive (aa) for the same trait.

If the dominant-expressing organism is a homozygote, all of the F1 offspring will display the dominant trait, indicating that the organism has two dominant alleles. Alternatively, if the organism is a heterozygote, the resulting F1 offspring will show a 1:1 phenotypic ratio of dominant to recessive traits, as half of the offspring will inherit the recessive allele and display the recessive phenotype. This validates Mendel's principle of segregation, where alleles segregate equally into gametes.