Question

Which type of Drosophila is produced, if (AA + X) ovum fertilizes with (A + Y) sperm?

• A. $0.67$, Sterile
• B. $0.33$, Super male sterile
• C. $0.67$, Inter sex sterile
• D. $0.5$, Normal male

Answer 1

The correct option is B $0.33$, Super male sterile

XXAA (diploid)	X:A ratio = 1	Female
XYAA / X0AA (diploid)	X:A ratio = 0.5	Male / sterile male
XXYAAA (aneuploid)	X:A ratio = 0.67	Intersex
XXXAAA (aneuploid)		X:A ratio = 1		Female
XYYAAA (aneuploid)	X:A ratio = 0.33	Super male sterile

In Drosophila, the sex determination is not based on sex chromosomes but it is based on the ratio of X chromosomes to the sets of autosomes. In Drosophila, there are 4 chromosomes, that is n=4. In this, 3 are autosomes and 1 is sex chromosome (X/Y). When ovum (AA+X) fertilizes with sperm (A+Y), it will produce offspring with genotype AAA+XY. In this, the X:A ratio is 0.33. Hence, it will produce super male sterile.

Thus, the correct answer is '0.33, Super male sterile.'