Question

White eyes in male fruit fly is determined by a
A. Dominant gene on X
B. Recessive gene on V
C. Dominant gene on V
D. Recessive gene on X

Answer 1

Hint: The fruit fly is used to research various biological researches for over many years. They can be used in the study of several biological processes like inheritance, embryonic development etc.

Complete answer:
-Drosophila is commonly called fruit fly or vinegar fly that we daily see in our homes. The most common species of Drosophila are Drosophila melanogaster.
-Drosophila melanogaster has sex chromosomes similar to humans like females have XX chromosomes and males with XY chromosomes. It is found that a trait like eye colour is related with a particular factor on the X chromosome then it is called X linked. Because males only have one X chromosome they display all X linked traits.
-Eye colour ranges from red to white depending upon the drosophila species and genetic makeup. Drosophila has four homologous pairs of chromosomes in which three are autosomes and one pair of sex chromosomes.
-X chromosome is responsible for the eye colour in Drosophila. Here the X chromosome does not directly pass from the father to offspring of the same sex but it has a criss cross pattern of inheritance and it is transmitted from one sex to the offspring of different sex.
-The white eye colour trait is recessive here. Therefore its effect is seen in males because of only X chromosomes. Female flies will show white eye colour when both the X chromosomes carry recessive alleles for white colour.
-So males have the white eye due to the trait found on their only X chromosome. Females do have the white eye trait as the trait was found in only one of its X chromosomes.

Hence, the correct answer is option (D).

Note: Drosophila is a very well-known model organism as:
-These flies maintenance is calm and are not very large.
-They can grow calmly with low food requirements.
-They have a short life-span and so their study becomes convenient.
-The genome size is smaller.