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Question
Which of the following statements is incorrect with respect to studies on linkage?
I. Morgan was the first to report linkage based on his studies on Drosophila.
II. Morgan observed that the two genes segregate independently of each other and the F2 phenotypic ratio is 9:3:3:1.
III. Morgan coined the term ‘recombination’ to describe the physical association of genes on a chromosome.
IV. Bateson and Punnett were the first to report linkage based on their studies on Lathyrus odoratus.
Which of the following statements is incorrect with respect to studies on linkage?
I. Morgan was the first to report linkage based on his studies on Drosophila.
II. Morgan observed that the two genes segregate independently of each other and the F2 phenotypic ratio is 9:3:3:1.
III. Morgan coined the term ‘recombination’ to describe the physical association of genes on a chromosome.
IV. Bateson and Punnett were the first to report linkage based on their studies on Lathyrus odoratus.
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Solution
The correct option is B I, II, and III
Linkage refers to the association of genes located on the same chromosome. The term ‘linkage’ was coined by Morgan to describe the physical association of genes on a chromosome.
Bateson and Punnett were the first to discover linkage in 1906 in their experimental organism sweet pea (Lathyrus odoratus). Morgan was the one who clearly proved and defined linkage based on his breeding experiment on Drosophila melanogaster. Hence statement IV is correct but statement I is incorrect.
Recombination refers to the appearance of new combinations of alleles in the offspring, which were not seen in the parental generation. Hence statement III is incorrect.
When he conducted dihybrid crosses in fruit fly, he observed that the F2 generation had more parental combinations than non parental combinations. When he crossed yellow body white eyed female with brown body red eyed male, in the F2 generation, he obtained 98.7% parental combinations and 1.3% new combinations. The results were not in the ratio of 9:3:3:1. It is because the genes didn’t segregate independently of each other, rather they were inherited as a single unit. Hence statement II is also incorrect.
Therefore statements I, II, and III are incorrect whereas statement IV is correct.
Linkage refers to the association of genes located on the same chromosome. The term ‘linkage’ was coined by Morgan to describe the physical association of genes on a chromosome.
Bateson and Punnett were the first to discover linkage in 1906 in their experimental organism sweet pea (Lathyrus odoratus). Morgan was the one who clearly proved and defined linkage based on his breeding experiment on Drosophila melanogaster. Hence statement IV is correct but statement I is incorrect.
Recombination refers to the appearance of new combinations of alleles in the offspring, which were not seen in the parental generation. Hence statement III is incorrect.
When he conducted dihybrid crosses in fruit fly, he observed that the F2 generation had more parental combinations than non parental combinations. When he crossed yellow body white eyed female with brown body red eyed male, in the F2 generation, he obtained 98.7% parental combinations and 1.3% new combinations. The results were not in the ratio of 9:3:3:1. It is because the genes didn’t segregate independently of each other, rather they were inherited as a single unit. Hence statement II is also incorrect.
Therefore statements I, II, and III are incorrect whereas statement IV is correct.
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