Question

In Thomas Hunt Morgan's experiments, the ratio of red-eyed flies to white-eyed flies appeared to follow a simple Mendelian pattern of inheritance. What observation(s) did he make that led to his conclusion that the white-eyed trait was actually not a simple Mendelian trait? He saw that only males had white eyes. O He observed that the white-eyed trait was recessive. O He was able to correlate the expression of white eyes to the inheritance of a Y chromosome because only F2 males had white eyes and the trait is recessive. He was able to correlate the expression of white eyes to the inheritance of an X chromosome because only F2 males had white eyes and the trait is recessive.

Answer 1

Answer: In 1902 and 1903, Sutton and Boveri proposed the chromosome theory of inheritance, in which they states that individual genes are found at specific locations on their particular chromosomes. The behavior of chromosomes during meiosis are inherited according to Mendel’s laws.

Morgan choose the fruit fly, Drosophila melanogaster, for his genetic studies, along with inheritance pattern and he found mutation in a gene affecting fly eye color. This mutation in Drosophila made a fly's eyes white, rather than their normal red.
When Morgan cross the white eye male fly crossed with red eye female fly, the first white-eyed fly he found was male, and when this fly was crossed with normal, red-eyed female flies, the F1 were all red eyed. When the F1 fly were crossed with each other and found strangely as all females were red eyed colour and males of F2 were white eyed colour.

Thus, clearly indicating that the male and female flies were inheriting the trait in different patterns. In fact, they were inheriting it in the same pattern as a particular chromosome, the X. Therefore, he was able to correlates the expression of white eyes to the inheritance of an X chromosome because only F2 males had white eyes and trait is recessive.