Question

When the phenotypic and genotypic ratios resemble in the \[{F_2}\] generation, it is an example of
A. Independent assortment
B. Qualitative inheritance
C. Segregation of factors
D. Incomplete dominance

Answer 1

Hint: By phenotypic ratio we mean the relative number of offspring that manifests physical expression of a particular trait or even a combination of traits. While genotype ratio is the set of genes that is present in our DNA which is responsible for a particular trait. \[{F_2}\] generation is produced as a result of a cross between two ${F_1}$ individuals.

Complete answer:
Two organisms that have even the slightest differences in their genes have different genotypes. Basically, a genotype means the genetic characteristics of an organism while a phenotype refers to the physical characteristics of the organism.
Independent assortment means that the alleles of two or more different genes get sorted into gametes which are independent of one another. Or we can say that the allele which a gamete receives for one gene does not influence the allele received for another gene. Hence, we can say that the phenotypic and genotypic ratios do not resemble the \[{F_2}\] generation.
Qualitative inheritance is an inheritance of a character that differs in its expression among individuals of a species. It produces a discontinuous trait variation in the offspring like either tallness or dwarfness. Hence qualitative inheritance is also not an example of the phenotypic and genotypic ratios that resemble the \[{F_2}\] generation.
According to Mendel’s Law of Segregation, individuals possess two alleles and a parent passes only one allele to his or her offspring, which also depicts that phenotypic and genotypic ratios do not resemble the \[{F_2}\] generation.
Incomplete dominance takes place when the phenotype of the heterozygous genotype is different form and most of the time intermediate to the phenotypes of the homozygous genotypes. Alleles of a given trait are expressed as a blend against a normal mendelian pattern where one of the alleles is dominant over the other. As a result of this blending, an intermediate character is being expressed.

Therefore, we can say that the correct answer is option D.

Note:
Incomplete dominance is also called partial dominance, semi-dominance or intermediate inheritance. It is a type of intragenic or interallelic interaction. As a result of incomplete dominance the heterozygous offspring will be phenotypically and also genotypically different from either of the homozygous parents.