Question

You have identified a new, recessively inherited trait in dogs: floppy ears. To determine if the gene for Floppy Ears is X-linked or not, you should:

Answer 1

Answer:

Cross a non-floppy-eared male to a floppy-eared female and observe if males offspring have the floppy ear trait

Explanation:

Mammals (e.g. dogs) have two sex chromosomes: X and Y. In the XY sex-determination system, the female gamete (i.e., the ovum) contributes to an X chromosome, while the male gamete (i.e., the sperm) contributes either an X chromosome or a Y chromosome: normal females are XX and normal males are XY. In consequence, a male always inherits its X chromosome from the mother and its Y chromosome from the father. In this case, the presence of the floppy ear trait in all males F1 offspring obtained by crossing a non-floppy-eared male to a floppy-eared female indicates that this trait is linked to the X chromosome because males inherit the floppy ear trait from the mother.