Question

If an X-linked recessive trait was lethal to the development of an embryo, answer the following questions:

A. could carrier females pass this trait to sons that survive child birth?

B. could carrier females pass this trait to daughters that survive child birth?

C. could fathers pass this trait to daughters that survive child birth?

D. could fathers pass this trait to sons that survive child birth?

Answer 1

QA) YES, the carrier female can pass the trait to sons that survive child Birth, because in Carrier female ,there chromosome contain A defectiveX chromsome with this trait and a normal Chromsome withou the trait that why they are called carriers.

When the carrier female is mated with a normal male , they can produce 50% of Affected son and 50% of normal son.

Because durong the gamete formation in female the Ddefective X cromsome goes to one gamete and normal X chromosome will goes to Other gamete.When these fuses with the Y chromosome of the father , 50% son will be with that Defective X chromosome and they will be Affected and other 50% son will be unaffected

QB)NO , because the crrier femal only contain one copy of defective X chromosome which will fuse with the normal chrmosome of male to form a carrier daughter.

The other Normal x chromosome of the carrier female fuse with the normal X chromosome of the Father to form Normal Daughter.( so 50% Carrier daughter and 50% Normal Daughter.)

QC)NO , Because the Affected father have only one copy of defective X chromosome , it will fuse with the Normal X chromosome of the mother to form Carrier Female .(All the Daughters will be Carriers)

QD)NO, because the Affected father have normal Y chromosome that will fuse with normal X chromosome of the female to Form normal son ( All son will be normal)

THIS IS WHY , IT IS SAID THAT THE X LINKED RECESSIVE TRAIT ARE TRANSFERED FROM ONLY CARRIER MOTHER TO SON.