Question

Coupling and Repulsion theory was proposed by
A. Morgan
B. Bateson
C. Muller
D. De Vries

Answer 1

When we say ‘Coupling’, it means that two dominant alleles are found in same homologous chromosomes. Whereas the other two recessive alleles stay in other homologous chromosomes. In the case of ‘Repulsion’, each homologous chromosome has one dominant and one recessive allele from two genes.

Complete answer:
1. Thomas Morgan invented various roles of chromosomes in activities of heredity. Throughout his life and research, he was more interested in Evolution of lives as per its entirety. Morgan worked with the flies Drosophila where he found that dominant alleles of two or more genes are present in one chromosome. This is called CIS Arrangement or coupling arrangement.
2. De Vries theory was related to evolution. According to him, mutations or discontinued variations are nothing but some raw materials of evolution.
3. Muller was the contemporary of Darwin. He is regarded as one of the early investigators of coevolution.
4. While working on sweet pea (Lathyrus odoratus), William Bateson observed that genes for flower colour and pollen shape that remain together and do not assort independently which was described in Mendel’s law of Independent assortment. He was the first person who used the term ‘genetics’ while describing the study of heredity.
5. Bateson described a cross in sweet pea he tried to exhibit a deviation from independent assortment. While they tested, they could not produce a 1:1:1:1 ratio but they found the ratio 1:7:7:1 of while testing the crosses.
6. In this context, we can say that Bateson was the proposer of Coupling and Repulsion Theory.

Hence the correct answer is option ‘B’.

Note: Bateson described the division of dominant and recessive alleles as gametic coupling. Similarly, we observed that two dominant alleles or two recessive alleles which come from different parents, used to remain separate. This is called Gametic Repulsion.