Question

In a testcross involving F1 dihybrid flies, more parental – type offspring were produced than the recombinant – type offspring. This indicates:

• A. The two genes are located on two different chromosomes
• B. Chromosomes failed to separate during meiosis
• C. The two genes are linked and present on the same chromosome
• D. Both of the characters are controlled by more than one gene

Answer 1

The correct option is C The two genes are linked and present on the same chromosome

If we recall Morgan's experiment, in which he found that when the two genes in a dihybrid cross were situated on the same chromosome, the proportion of parental gene combinations were much higher than the non - parental type. He attributed this due to the physical association or linkage of the two genes and coined the term as linkage to describe this physical association of genes on a chromosome and the term recombination to describe the generation of non - parental gene combinations.

So in a testcross involving F1 dihybrid flies, if more parental – type offspring were produced than the recombinant – type offspring, that means the two genes are linked and present on the same chroomosome.