Question

The genes for the traits that Mendel worked with are either all located on different chromosomes or behave as if they were. How did this help Mendel recognize the principle of independent assortment?
a. Otherwise, his dihybrid crosses would not have produced a 9 : 3 : 3 : 1 ratio of F2 phenotypes.
b. The occurrence of individuals with unexpected phenotypes led him to the discovery of recombination.
c. It led him to the realization that the behavior of chromosomes during meiosis explained his results.
d. It meant that the alleles involved were either dominant or recessive, which gave 3 : 1 ratios in the F1 generation.

Answer 1

Answer:

Otherwise, his dihybrid crosses would not have produced a 9 : 3 : 3 : 1 ratio of F2 phenotypes.

Explanation:

The random separation of alleles of different genes to the opposite poles of the cell requires that the genes are present on the different chromosomes. In this case, the random segregation of alleles of two genes produces new allele combinations in the progeny. The genes may be present on the same chromosome. These linked genes do not exhibit the random separation of their alleles.

Mendel obtained the 9:3:3:1 ratio since the two genes of a dihybrid cross were present on the different chromosomes. This allowed the independent assortment of their alleles. If the genes were linked, he would have obtained more of the parental types and less or no recombinant progeny in the F2 generation. Therefore, the F2 phenotypic ratio would have deviated.