Question

Sex linkage was discovered by

• A. Morgan
• B. Linnaeus
• C. Calvin
• D. Mendel

Answer 1

The Correct Option is A

• Sex linkage was discovered by Thomas Hunt Morgan in 1910. The discovery stemmed from Morgan's observation of an anomaly in a male fruit fly: instead of the typical red eyes, this particular fly exhibited white eyes.
•  Intrigued by this deviation, Morgan embarked on a comprehensive study of fruit fly breeding.
• Fruit flies, scientifically known as Drosophilas, were readily available and conveniently located near Morgan's laboratory at Columbia University.
•  This accessibility facilitated Morgan's research, allowing him to closely observe the breeding and genetic patterns of these flies across multiple generations.
• Morgan conducted cross-breeding experiments involving different varieties of fruit flies, meticulously recording and analyzing the outcomes.
• Through his systematic investigations, Morgan made groundbreaking discoveries that laid the foundation for our understanding of sex-linked inheritance and genetic mechanisms.
   

cross	Observed phenotypes
P1 Red-eyed fly (female) + P1 white-eyed male	F1 = all red-eyed flies
F1 Red-eyed fly (female)  = F1 Red-eyed fly (male)	50% = red-eyed female 25% =  Red-eyed male 25% = white-eyed male

Through his research on fruit flies, Thomas Hunt Morgan not only confirmed the chromosome theory but also provided significant evidence for the concept of sex linkage in inheritance. By meticulously analyzing the patterns of inheritance in fruit flies, Morgan demonstrated that specific traits could be inherited from parents to offspring through the sex chromosomes. This groundbreaking discovery further solidified our understanding of genetics and laid the groundwork for subsequent research in the field. Morgan's work marked a pivotal moment in the history of genetics, shaping our understanding of heredity and inheritance mechanisms.

Answer 2

T.H. Morgan discovered sex-linkage in Drosophila. He observed a white-eyed male mutant, crossed it with red-eyed females, and found all F1 offspring had red eyes, showing white is recessive.
In F2, the ratio was 3:1 red to white, with white eyes only in males. Reciprocal crosses showed F1 females were red-eyed and males were white-eyed. In F2, both genders were 50% red-eyed and 50% white-eyed.
Thus, option C is correct.