In Suffolk sheep, horns are a sex-influenced trait. The presence of horns is dom
ID: 168105 • Letter: I
Question
In Suffolk sheep, horns are a sex-influenced trait. The presence of horns is dominant in males and recessive in females. Which of the following statements would be true? (Choose all that apply.)
A) Only males can have horns
B) Hornless females can produce only hornless sons
C) A hornless male and a hornless female may have horned sons
D) A hornless male and a hornless female may have horned daughters
E) A horned female and a hornless male will produce only horned males and hornless females.
A) Only males can have horns
B) Hornless females can produce only hornless sons
C) A hornless male and a hornless female may have horned sons
D) A hornless male and a hornless female may have horned daughters
E) A horned female and a hornless male will produce only horned males and hornless females.
Explanation / Answer
ANSWER:-
E) A horned female and a hornless male will produce only horned males and hornless females.
InSuffolksheep, both sexes are hornless and homozygous recessive (hh).WhenDorset(horned) are crossed toSuffolk(hornless), the F1(h+h)are found to be horned males and hornless females. When F1's (h+h)are intercrossed, in the resulting F2progeny, males segregated as 3 (horned) to 1 (hornless), while females segregated as 1 (horned) to 3 (hornless). It is thus obvious that expression of only heterozygote (h+h)is influenced by sex,h+hbeing horned in male and hornless in female . In other words, while horned character is dominant in male, it is recessive in female. This influence is believed to be mainly dueto male and female hormones.Certain characters in human beings which are not located on sex chromosomes, are also believedto be sex influenced. For instance, white forelock (areas of skin completely without pigment), absence of upper lateral incisor teeth, a type of enlargement of terminal joint fingers, harelip (a fissure in upper lip), cleft palate (a fissure in roof of mouth) and stuttering (involuntary repeats of letters or words) are more common and more severely influenced in males.
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