Final answer:
The % of thread of the internal thread being affected by the described sex-linked eye color ratio in fruit flies is False. Eye color in these insects is indeed sex-linked, and the inheritance pattern can result in different eye colors in offspring, depending on the parents' genetic makeup.
Step-by-step explanation:
Understanding Eye Color Inheritance in Fruit Flies
When considering the inheritance of eye color in fruit flies, we know that eye color is sex-linked, specifically linked to the X chromosome. In fruit flies (Drosophila melanogaster), red eyes are dominant while white eyes are recessive. For a cross between a white-eyed male (also called hemizygous recessive) and a female that is heterozygous for red eye color, the expected ratio of offspring will depend on these genetic combinations.
A heterozygous red-eyed female has one dominant allele for red eyes and one recessive allele for white eyes. Since the white-eyed male has only one X chromosome with the white eye allele, all his offspring will inherit that white eye allele, resulting in different ratios of eye color based on the sex of the offspring due to males inheriting the Y chromosome from him.
Answering the original question, the statement regarding the % of thread of internal thread being affected by a 3:1 ratio of females with red eyes to males with white eyes is False. This statement seems to inaccurately describe a situation and confuses concepts of mechanical threads with genetic inheritance patterns in fruit flies.