Question

Coupling and repulsion hypothesis was given by
A. Bateson and Morgan
B. Morgan and Punnet
C. Bateson and Punnett
D. Morgan and Miller

Answer 1

Hint: The scientists who gave the coupling and repulsion hypothesis worked on sweet pea or Lathyrus odoratus. They found out that linkage was an exception to the theory of independent assortment.

Complete answer:
The coupling and repulsion hypothesis was proposed by Bateson and Morgan, they observed that genes related to the color and shape of pollen were not showing independent assortment.

Additional Information:
> In the experiments conducted by Bateson and Punnett, they observed that the test cross ratio was 7:1:1:7 instead of 1:1:1:1.
>They provided the theory of Coupling and Repulsion to explain this. Coupling is the condition where the genes that are coming from the identical parents enter the same gamete are inherited together. In repulsion, the genes are coming from different parents and therefore are separated in different gametes which are separately inherited.
> T H Morgan worked on a species of Drosophila and along with another scientist proposed the chromosomal theory of linkage.

The key points of the chromosomal theory of linkage are as follows:
- Linked genes are situated on the same chromosome.
- These linked genes are unitedly inherited.
- The arrangement of genes on a chromosome is linear.
- The strength of linkage is related to the distance between two genes inversely.
- According to this theory coupling and repulsion were two features of linked genes.

So, the correct answer is ‘Bateson and Punnett’.

Note:
Linkage is related to the study of the process where all genes located on a single chromosome are inherited together. It is of two types, complete linkage, and incomplete linkage. The total number of genes present together on a chromosome is known as linked genes and together they form a group known as linkage group. This overall number of linkage groups equals the haploid chromosome number in an organism.