Question

In which sex would you expect the X-linked traits to be found in most frequently in each of the following species: dogs, grasshoppers, robins?

a) Male
b) Female
c) Both sexes equally
d) Cannot be determined

Answer 1

In dogs and grasshoppers, X-linked traits are found more frequently in males due to their XY or X0 sex determination system, respectively. In robins, which are birds with a ZW sex determination system, these traits are more frequently found in females, as they carry only one Z chromosome.

Step-by-step explanation:

In the context of X-linked traits, their expression varies by sex and is influenced by the chromosomal sex determination system of the species. For the dogs, which are mammals, males have one X and one Y chromosome (XY), while females have two X chromosomes (XX).

Thus, X-linked traits are more frequently expressed in males because they only have one X chromosome, and a single recessive allele on this chromosome will result in the trait being expressed. In contrast, females need two copies of the recessive allele, one on each of their X chromosomes, to express the trait. For the grasshoppers, they have an XO sex determination system, where males have a single X chromosome (X0) and females have two X chromosomes (XX). Therefore, similar to mammals, X-linked traits are also more likely to be expressed in male grasshoppers.