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What is the likely proportion of white-eyed and red-eyed flies in a cross between a red-eyed male (XY) and a white-eyed female (XwXw)?

a. 100% white-eyed
b. 50% red-eyed, 50% white-eyed
c. 75% red-eyed, 25% white-eyed
d. 100% red-eyed
e. 25% red-eyed, 75% white-eyed

User Kklw
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1 Answer

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Final answer:

A cross between a red-eyed male fruit fly and a white-eyed female fruit fly will likely yield 50% red-eyed and 50% white-eyed offspring, following the patterns of sex-linked inheritance.

Step-by-step explanation:

When crossing a red-eyed male fruit fly (XY) with a white-eyed female (XwXw), the resulting offspring will follow the patterns of sex-linked inheritance of the eye color trait in fruit flies.

The eye color gene is located on the X chromosome and red eye color (X) is dominant over white eye (Xw). Here's how the genetics works out:

The male fruit fly has one X chromosome with the red-eye allele (X) and one Y chromosome (Y), so he can only pass on these chromosomes onto his offspring.

The female fruit fly has two X chromosomes with the white-eye allele (XwXw) and can pass on either Xw chromosome. As a result, the expected offspring would be:

  • 50% male offspring with the genotype XwY, which are white-eyed.
  • 50% female offspring with the genotype XXw, which are red-eyed because they have one red-eye allele (dominant).

Therefore, the likely proportion of white-eyed to red-eyed flies would be 50% red-eyed, 50% white-eyed (option b).

User Serge Hendrickx
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