Question

In Drosophila, the sex is determined by

• A. The ratio or pairs of X-chromosomes to the pairs of autosomes
• B. Whether the egg is fertilised or develops parthenogenetically
• C. The ratio of number of X-chromosomes to the set of autosomes
• D. X and Y-chromosomes

Answer 1

The correct option is C The ratio of number of X-chromosomes to the set of autosomes

Drosophila flies have both X and Y chromosomes, as well as autosomes. Unlike humans, the Y chromosome does not confer maleness; rather, it encodes genes necessary for making sperm. Sex is instead determined by the ratio of X chromosomes to autosomes (genic balance theory). It was demonstrated by Calvin Bridges.