Question

In Drosophila, the sex index of super female is
A. 1
B. 0.5
C. 1.5
D. 0.67

Answer 1

Hint: The sex index of the Drosophila will be determined by the ratio of the chromosomes that will be of both sex chromosomes and the autosomes present in it.

Complete answer:
The genic balance theory was given by Calvin Bridge in 1926 it explains us about the sex Index of a fruit fly which can be explained by the total number of X chromosomes and the autosomal chromosomes that is XY chromosomes does not tells us about the sex but the ratio between X chromosomes and autosomes does.
According to Bridge the chromosome in drosophila is heterochromatic and inactive in determination of sex. Y chromosome is responsible for male fertility so if the value comes 1 the offspring will be female and if it is 0.5 the offspring will be male and having the sex index ratio of less than 0.5 will be supermale and more than one will be super female respectively.
The sex of the organism is considered by the number of sex chromosomes i.e X and Y chromosomes. According to the genic balance theory of sex determination, if the numbers of X chromosomes to the total number of autosomes are in the ratio greater than 1, then the Drosophila will be super female, whereas if the ratio is smaller than 1 and greater than 0.5 it is intersex (0.67), equal to 0.5 will be male and if the ratio is equal to 1, it will be normal female.

The correct answer is (C) The sex index of super female is 1.5

Note: The ratio of X chromosomes to the total number of autosomes will determine the sex of the Drosophila. The ratio should be studied carefully whether it is smaller, equal or greater than 1.