The presence of horns in a certain breed of sheep is due to

The presence of horns in a certain breed of sheep is due to a sex-influenced trait with horns being dominant in males and recessive in females. A hornless male is bred with a horned female. The F1 generation are then crossed. What fraction of the F2 females is expected to have horns? 25% 12.5% 50% 0% 75%

Solution

The genes controlling the horned character in sheep are h and h+

hornless makes are hh and horned females are h+h+

horned character is dominant in males and recessive in females

when we cross them we get-

F1 generation -

now we cross h+h and h+h to get f2 generation :

now only h+h+ females can have horns

probability of that is 25% = 1/4

probability of being a female is 50% = 1/2

1/4 * 1/2 = 1/8

1/8 * 100 = 12.5%

h+h	h+h
h+h	h+h