Red-eyed female White-eyed male

P1 R R X r

XX XY

G1

R r R

F1 XX XY

Red-eyed female Red-eyed male

Red-eyed insects

Red-eyed female Red-eyed male

P2 R r X R

XX XY

G2

R r R R r r

F2 XX XY XX XY

Red-eyed Red-eyed Red-eyed White-eyed

Female male female male

Red-eyed insects White-eyed insects

3 : 1

Uses of Morgan assumption:

· Morgan assumption in which he determined the location of the white-eyed recessive gene on the sex chromosome X has explained the results of his experiments.

· Morgan has predicted from his assumption the possibility of obtaining white-eyed females by crossing red-eyed females (whose male parents were white-eyed) with white-eyed males. When Morgan performed this cross he obtained insects with red eyes and others with white eyes in the ratio 1:1. However, 50% of the white-eyed insects were females. Thus, Morgan was able to prove the validity of his prediction according to the above mentioned assumption.

· Morgan's chromosome theory i.e. genes are carried on chromosomes, became valid.