Question

Which of Thomas Hunt Morgan’s hypotheses was valid?

Answer 1

Hint Thomas Hunt Morgan was an American zoologist and geneticist who was famous for his experimental research on a fruit fly by which he can establish the chromosomal theory of heredity. He was awarded with the Nobel prize in 1933 for the discovery of white eyed mutation in the fruit fly. He worked and completed this discovery in about 17 years.

Complete Answer- Thomas Hunt Morgan worked with fruit fly to show that genes are linked in a series on the chromosomes and are responsible for hereditary traits.
He was the first who discovered or identified that the genes are linked and arranged linearly to the same chromosomes. The genes which have low combination frequencies must be closer and hence, it is difficult to separate them.
For example- if a gene contains two identical alleles, either dominant or two recessive alleles then it is called homozygous dominant and homozygous recessive. White eyes of fruit flies are homozygous recessive.
Thomas Hunt Morgan hoped to discover large scale mutations which can represent the emergence of new species. After the trial of millions of the Drosophila, Morgan noticed only one fruit fly with different characters that is white eyes instead of red eyes. This is the reason that he isolated this specimen.

Thus, Morgan confirmed the laws of Mendel and the hypothesis that genes are located on chromosomes i.e chromosomal theory of heredity.

Note- After this discovery, he would be able to discover more mutant traits between the time period of 1911-1914.
When Thomas tried to research Drosophila, he got F1 generation with all white-eyed male and a red-eyed female. A female has red eyes because every chromosome pair has at least one copy of X chromosome with the dominant trait.