Question

According to genic balance theory of Bridges, Drosophila autosomes bear genes which incline
for
A) Femaleness
B) Maleness
C) Both A and B
D) None of the above

Answer 1

Hint:- The theory of genic balance states that instead of XY chromosomes, sex is concluded by the genic steadiness or proportion between X-chromosomes and autosome genomes specified by Calvin Bridges. In easier terms, by a balance of female determinants on the X chromosome and male determinants on the autosomes the sex determination is attained. This kind of sex determination is known as the genic balance system.

Complete step-by-step solution:-
“Genic Balance Theory” was recommended by C. B. Bridges in 1922, for sex determination in Drosophila. It affirms that the ratio of the number of X-chromosome to that of a complete set of autosomes determines the sex of Drosophila. If the ratio of the X chromosome to a whole number of sets of autosomes (X/A) is > 1, the individual will be a super female according to this hypothesis of sex determination. The genotype will show the intersex phenotype. The X/A value is 1.0 for ordinary females and 0.5 for an ordinary male if the ratio of X chromosome to the full figure of sets of autosomes (X/A) falls amid 1 and 0.50. It obviously demonstrates that the Drosophila autosome possesses genes that incline for maleness and X chromosomes to bear genes which incline for femaleness.
Thus, the right answer is option B.

Note:- The sex determination in Drosophila is moderately different from humans. Drosophila has eight chromosomes (n = 4), three sets of autosomes, and one pair of sex chromosomes. Even though Drosophila owns XX and XY sex chromosomal association, unlike human beings, the Y chromosome does
not have any function in determining the sex of individuals. The sex in Drosophila is decided by the ratio
of the number of X chromosomes to that of the number of sets of autosomes.