Grade 12 Biology: Sex-Linked Traits
Explore the inheritance patterns of sex-linked traits, including X-linked and Y-linked disorders, and analyze pedigree charts.
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Grade 12 Biology: Sex-Linked Traits
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Read each question carefully and answer to the best of your ability. Show all work for genetic crosses.
1. Which of the following best describes a sex-linked trait?
A trait determined by genes on any autosome.
A trait determined by genes located on the X or Y chromosome.
A trait that is expressed only in one sex.
A trait that is always dominant.
2. Why are X-linked recessive traits more common in males than in females?
Males have two X chromosomes.
Males have a Y chromosome which carries the recessive allele.
Males only have one X chromosome, so a single recessive allele will be expressed.
Females are always carriers of X-linked recessive traits.
3. Genes located on the sex chromosomes are called traits.
4. In humans, females have two chromosomes, while males have one and one chromosome.
5. A female who carries a recessive allele for an X-linked trait but does not express the trait herself is called a .
6. Red-green color blindness is an X-linked recessive trait. A colorblind man marries a woman who is a carrier for color blindness. What is the probability that their son will be colorblind? Use a Punnett square to show your work.
7. Hemophilia is another X-linked recessive disorder. If a normal man marries a woman who is a carrier for hemophilia, what is the probability that their daughter will have hemophilia? Explain your reasoning.
8. All traits located on the X chromosome are expressed equally in males and females.
True
False
9. Y-linked traits are passed directly from father to all his sons.
True
False