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What are the sex-chromosome constitution (X and Y chromosomes) of the inviable offspring

resulting from a cross between a white-eyed female (Xw XwY) and a wild-type male (normal
chromosome complement) in Drosophila melanogaster?
A) XwXwY and YY
B) X+XwY and X+XwXw
C) X+Y
D) YY and XwYY
E) X+XwXw and YY

1 Answer

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Final answer:

The sex-chromosome constitution of the inviable offspring from a cross between a white-eyed female (XwXwY) and a wild-type male in Drosophila melanogaster is XwXwY and YY.

Step-by-step explanation:

The sex-chromosome constitution of the inviable offspring resulting from a cross between a white-eyed female (XwXwY) and a wild-type male in Drosophila melanogaster would be (A) XwXwY and YY. The female fruit fly (XwXwY) has an abnormal chromosome composition, featuring two X chromosomes and one Y. This is typically lethal in Drosophila because it disrupts the balance of sex chromosomes, making the offspring inviable.

The white-eyed female can only pass on an Xw or the Y chromosome. A normal XY male will pass on either his X or Y chromosome. Therefore, potential inviable combinations would be XwXwY (having received an Xw from the mother and another Xw from the father, as well as the Y from the mother) or YY (having received Y chromosomes from both parents).

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