Sex determination in grasshoppers, humans, and Drosophila is similar because

Sex determination in grasshoppers, humans, and Drosophila is similar because males have one X-chromosome & females have two X-chromosomes. In these three species, females have two X-chromosomes and males have one X-chromosome. The ratio of X-chromosomes to autosomes is important (and different in each organism) in Drosophila and grasshoppers, but not in humans. In all three species, males have one Y-chromosome, but the Y-chromosome is required for male fertility, not for Drosophila to be male (in Drosophila, male flies can be XO).