Biology: A Guide to the Natural World

Chapter 12: Chromosomes and Inheritance

Post-quiz: Traits and Chromosomes

1. Duchenne muscular dystrophy is caused by a sex-linked allele. Its victims are almost always boys who die before the age of 20. Why is this disorder almost never seen in girls? [Hint]

2. Hemophilia is a sex linked disorder. Which is the best prediction of the offspring if the mother is a carrier and the father has hemophilia? [Hint]

3. When can a trait be expressed when only one allele for that trait is present? [Hint]

4. A female is born with color blindness. What must have happened? [Hint]

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