Question

What is the sexual phenotype of a fruit fly that has XXYYY sex chromosomes and two sets of autosomes?
A) Male
B) Intersex
C) Female
D) Metamale

Answer 1

Hint: The off-springs are generated by the sexual reproduction of two sexes. Sex determination is a system that determines the development of sexual characters in an organism. In Drosophila, the ratio of the X chromosomes to the autosomes determines the sex. The Y chromosome has no role in the maleness of the fly.

Complete answer:
We already know that Drosophila is an important model to study sex determination. In the case of drosophila, both X and Y chromosomes are present along with the autosomes. The ratio of the X chromosome to the autosome determines the maleness.
- If the ratio of X chromosome to autosome is 1, then female.
- If the ratio is greater than 1 then metafemale.
- If the ratio is less than 1 then intersex.

In the question given, there are 2X chromosomes and two autosomes. The ratio is equal to 1. So, the sex of the fly is female. If the XO or XY chromosome are present along with two autosomes then the sex of the organism is male. Metamale is also called super male if the ratio of X to autosome is less than 0.5. 3A+XY is responsible for metamale. From the above discussion, we can conclude that the sexual phenotype of a fruit fly that has XXYYY sex chromosomes and two sets of autosomes is a female.

Thus the correct answer is option ‘C’.

Note: In the case of humans, the Y chromosome determines the male. The Females are represented by XX and the males by XY. In humans, both genes are responsible for fertility. The females produce ovules which are larger gametes as compared to the spermatozoa which are produced by male reproductive cells.