Tony and Tina are both carriers of the same defective gene for a genetic disorder. As knowledgeable individuals, they know that each time they have a child there is a _____ risk that child will be a carrier for the disorder.
a. 25 percent
b. 50 percent
c. 75 percent
d. 100 percent
Question 2An individual who is a carrier of a trait has
a. two dominant genes, both calling for the presence of the trait.
b. two recessive genes, both calling for the presence of the trait.
c. one dominant gene calling for the absence of the trait and one recessive gene calling for the presence of the trait.
d. one dominant gene calling for the presence of the trait and one recessive gene calling for the absence of the trait.
Question 3Which disorder is associated with intellectual disability unless the affected individual adheres to a special diet?
a. PKU.
b. hemophilia.
c. sickle-cell disease.
d. Tay-Sachs disease.
Question 4Which statement concerning Huntington's is true?
a. It typically strikes in adolescence.
b. It disrupts the nervous system.
c. It is a sex-linked trait.
d. It is best classified as a chromosome abnormality.
Question 5The gene responsible for sickle-cell disease is thought to have arisen from a mutation that protected against
a. leukemia
b. malaria
c. multiple myeloma
d. Chagas disease
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