Michigan Test for Teacher Certification (MTTC) Secondary Integrated Science Practice test

Which statement is true regarding sex-linked traits?

1. They are equally expressed in both males and females

2. They are more likely to manifest in females

3. They are usually found on the X chromosome

4. They are predominantly independent of sex

The correct answer is: They are usually found on the X chromosome

Sex-linked traits are typically associated with genes located on the X chromosome. This is significant because males have one X chromosome and one Y chromosome (XY), while females have two X chromosomes (XX). When a trait is recessive and located on the X chromosome, males are more likely to express that trait because they do not have a second X chromosome that could mask the recessive allele. Conversely, females can be carriers of X-linked recessive traits if they have one normal allele on their other X chromosome, meaning they may not express the trait themselves. Therefore, the correct statement underscores the specific chromosomal location of sex-linked traits, emphasizing their relationship to the X chromosome and how it influences inheritance patterns. This location affects the prevalence of these traits among genders, but the definitive characteristic of sex-linked traits is their connection to the X chromosome itself.