Question

In some goats, the presence of horns is produced by an autosomal gene that is dominant in males and recessive in females. a horned female is crossed with a hornless male. the f1 offspring are intercrossed to produce the f2. what proportion of the f2 females will have horns?

Answer 1

`(1)/(4)`of the f2 females will have horns

Step-by-step explanation:

Let the "presence of horn" trait be represented by "H"

and the "absence of horn" trait be represented by "h"

Given presence of horn is a dominant trait in males and recessive trait in females.

F1 Cross -

Horned female genotype - HH

Hornless male genotype - hh

HH * hh

Hh, Hh, Hh, Hh

F2 Cross

Hh * Hh

HH, Hh, Hh, hh

Only one female will have horns

`(1)/(4)`of the f2 females will have horns

Answer 2

Taking; H+ = allele for the presence of horns
H- = allele for hornlessness
Since H+ is recessive in females, the horned female parents must be H+H+. The hornless male is H-H- because the absence of horns is recessive in males. Then their F1 progeny must be all heterozygous H+H-. An intercross of the F1 would produce both male and female progeny in the ration of 1 H+H+, 2 H+H-, and 1 H-H-. Additionally, remembering that H+ is recessive in females, we would expect a ratio of 3:1 hornless to horned females.