Question

In Mendel’s dihybrid cross experiments, if he had used two such characters which were linked, he would have faced difficulty in explaining the
A. Law of segregation
B. Law of multiple-factor hypothesis
C. Law of independent assortment
D. Law of dominance

Answer 1

Hint: A dihybrid cross is a mating experiment between two organisms that are identically hybrid of two traits. The organism is heterozygous, which means it carries two different alleles at a particular genetic position or locus on the chromosome. Therefore, a dihybrid organism is heterozygous at two different genetic loci.

Complete solution: Monohybrid cross is the base of the law of segregation. According to this law, in F2 hybrid generation, the dominant and recessive genes remain together for a long time, but they do not mix with each other and segregate at the time of gamete formation. Dihybrid cross is the basis of the Law of independent assortment. This law states that the inheritance of one allele does not dependent on the inheritance of other alleles of the same chromosome in the same individual. if the inheritance of more than one allele is done, then the gene for each character will assort out independently of the other factor or gene. Linked genes do not show independent assortment. Lastly, Mendel's law of dominance states that in a heterozygote, when a gene contains two alleles or traits in which one trait will conceal the presence of another trait for the same characteristic. Rather than both alleles contributing to a phenotype, the dominant allele will be expressed exclusively. The allele which conceals another trait is called the dominant trait and the allele which was concealed is called a recessive trait.
Hence, the correct answer is option C.

Note: The F2 progeny of Mendel dihybrid cross had a 9:3:3:1 ratio which produced nine plants with round, yellow seeds; three plants with round, green seeds; three plants with wrinkled, yellow seeds, and one plant with wrinkled, green seeds.