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Question
Coupling and Repulsion theory was proposed by
Coupling and Repulsion theory was proposed by
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Solution
The correct option is A Bateson
W. Bateson described a cross in sweet pea, where a deviation from independent assortment was exhibited. Plants of a sweet pea variety having blue flowers (B) and long pollen (L) were crossed with those of another variety having red flowers (b) and round pollen (l). F1 individuals (BbLl) had blue flowers and long pollen. These were crossed with plants having red flowers and round pollen (bbll). (In this case character for blue colour of flowers is dominant over red colour and long pollen character is dominant over round pollen).
Normally, if independent assortment takes place, we should expect 1:1:1:1 ratio in a testcross. Instead, 7:1:1:7 ratio was actually obtained, indicating that there was a tendency in dominant alleles to remain together. Similar was the case with recessive alleles. This deviation was, therefore, explained as the gametic coupling by Bateson. Similarly, it was observed that when two such dominant alleles or two recessive alleles come from different parents, they tend to remain separate. This was called as gametic repulsion.
In Bateson's experiment in repulsion phase, one parent would have blue flowers and round pollen (BBll) and the other would have red flowers and long pollen (bbLL). The results of a testcross in such a repulsion phase were similar to those obtained in coupling phase giving 1:7:7:1 ratio instead of expected 1:1:1:1. Bateson explained the lack of independent assortment in the above experiments by means of a hypothesis known as coupling and repulsion hypothesis.
W. Bateson described a cross in sweet pea, where a deviation from independent assortment was exhibited. Plants of a sweet pea variety having blue flowers (B) and long pollen (L) were crossed with those of another variety having red flowers (b) and round pollen (l). F1 individuals (BbLl) had blue flowers and long pollen. These were crossed with plants having red flowers and round pollen (bbll). (In this case character for blue colour of flowers is dominant over red colour and long pollen character is dominant over round pollen).
Normally, if independent assortment takes place, we should expect 1:1:1:1 ratio in a testcross. Instead, 7:1:1:7 ratio was actually obtained, indicating that there was a tendency in dominant alleles to remain together. Similar was the case with recessive alleles. This deviation was, therefore, explained as the gametic coupling by Bateson. Similarly, it was observed that when two such dominant alleles or two recessive alleles come from different parents, they tend to remain separate. This was called as gametic repulsion.
In Bateson's experiment in repulsion phase, one parent would have blue flowers and round pollen (BBll) and the other would have red flowers and long pollen (bbLL). The results of a testcross in such a repulsion phase were similar to those obtained in coupling phase giving 1:7:7:1 ratio instead of expected 1:1:1:1. Bateson explained the lack of independent assortment in the above experiments by means of a hypothesis known as coupling and repulsion hypothesis.
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