Question

PLEASE HELP RIGHT AWAY!!!!

Which allele combination represents a female who has a heterozygous sex-linked trait?
XRY
XrY
XRXr
XRXR

Answer 1

Ans.

A sex-linked trait is defined as character, determined by the genes present on sex chromosomes. In humans, females have two sex chromosomes (XX) and a heterozygous individual shows presence of different or alternative alleles for a trait.

Therefore, a female showing heterozygous sex-linked trait will show XRXr as one of its X chromosome carries wild type allele (R), while another X chromosome carries mutated (r) allele.

Thus, the correct answer is 'option). XRXr.'

Answer 2

The answer is XRXr. X and X is female, so it wouldn't be the first two answers because those have Y. RR or rr is homozygous because they're the same alleles (two big R's or two little r's), and Rr is heterozygous because they're different alleles (one big R and one little r).