Question

According to genic balance theory of Bridges, Drosophila autosome bear genes which incline for

• A. Femaleness
• B. Maleness
• C. Both A and B
• D. None of the above

Answer 1

The correct option is B Maleness

'Genic Balance Theory' was proposed by C. B. Bridges in 1922, for sex determination in Drosophila. It states that ratio of number of X-chromosome to that of complete set of autosome determine the sex of Drosophila. According to this theory of sex determination, if the ratio of X chromosome to total number of sets of autosomes (X/A) is > 1, the organism will be a super female. If the ratio of X chromosome to total number of sets of autosomes (X/A) falls between 1 and 0.50, the genotype will show intersex phenotype. The X/A value is 1.0 for normal female and 0.5 for normal male. It clearly shows that Drosophila autosome bear genes which incline for maleness and X chromosomes bear genes which incline for femaleness.

Thus, the correct answer is option B.