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MCQ- Genetics

  • #1

Homework Statement


In an organism allele for red eye colour is dominant over allele for white colour. A cross is made between a white eyed male and a red eyed female. In the progeny all males are red eyed and females are white eyed. The reciprocal cross leads to all red eyed progeny. Based on the above information choose the correct statement.

1. This is a sex linked trait and the male is homorphic sex
2 This is a sex limited trait and the male is the sex limited trait.
3 This is a sex linked trait and the female is the homorphic sex.
4 This is a case of autosomal inheritance with incomplete inheritance.


2. The attempt at a solution
Male:WW x Female:RW --- Red males RW & White females WW

Male:RW/RR x Female:WW ---- RW red progenies, WW progenies are not expressed hence incomplete penetrance.

I don't have the answer. Is it correct?
 

Answers and Replies

  • #2
Ygggdrasil
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Well, the first thing to consider is whether you think the trait is sex-linked or autosomal.
 
  • #3
The trait is not sex linked because in reciprocal cross there are no white male progenies, all are red. So the first 3 options are not valid. The trait is autosomal.


*Option four has a mistake: This is a case of autosomal inheritance with incomplete penetrance

In the first cross, red females and white males are also possible, but it doesn't appear in the F2 gen, so we can say there is incomplete penetrance.
 
  • #4
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The trait is autosomal.
Then why is there a sex difference when breeding a white eyed male and a red eyed female?
 

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