Someone who is heterozygous for a recessive allele that causes a disorder ?

A. is not a carrier of the disorder.
B. will not have the disorder.
C. cannot have offspring with the disorder.
D. will get the disorder late in life.

2. The Punnett square in Figure 7.1 shows a cross between two parents who are heterozygous for an autosomal genetic disorder caused by a recessive allele. People with which genotype will have the disorder?
A. Ss parent
B. ss offspring
C. SS offspring
D. Ss offspring

3. An XX female will express a recessive sex-linked trait if she
A. has several codominant alleles for the gene.
B. fully expresses her Y chromosome.
C. carries the allele on an epistatic gene.
D. is homozygous for the recessive allele.

4. Suppose a mouse is homozygous for alleles that produce black fur and homozygous for alleles of an epistatic gene that produces albinism. What color fur will the mouse have?
A. Black
B. White
C. Gray
D. Spotted

5. The crossing of wild type fruit flies with mutant fruit flies resulted in the conclusion that some
A. traits are inherited as a group.
B. chromosomes are inherited as a group.
C. genes assort independently.
D. traits assort independently.

6. A female is born with attached earlobes, which is a recessive phenotype. Which of the following statements about her parents must be true?
A. Neither has the codominant allele.
B. Both parents have the recessive allele.
C. Her father has an inactivated allele.
D. Her mother carries the dominant allele.

7. If more males than females in a family have a recessive sex-linked disorder, what can you infer about patterns of inheritance in that family?
A. The males would pass on the disorder to sons.
B. All females would be carriers of the disorder.
C. Only females would be carriers of the disorder.
D. Females would not develop the disorder.

8. Down syndrome is characterized by having an extra copy of at least a portion of chromosome twenty-one. Which of the following methods would quickly identify the disorder?
A. Linkage map
B. Meiosis map
C. Karyotype
D. Pedigree chart

9. __________ occurs in cells of female mammals.
A. X chromosome revitalization
B. Y chromosome inactivation
C. X chromosome inactivation
D. Y chromosome expression

10. A plant that is homozygous for red flowers is crossed with a plant that is homozygous for white flowers. The flowers of the offspring are all pink. This is an example of
A. complete recession.
B. incomplete recession.
C. complete dominance.
D. incomplete dominance.

11. Studying genetic disorders has resulted in much of what we know about
A. single-expression dominance.
B. somatic gene disruptions.
C. multiple-gene traits in humans.
D. single-gene traits in humans.

12. Traits that result from many genes are called
A. monogenic traits.
B. multigenic traits.
C. polygenic traits.
D. monolithic traits.

13. Suppose that the cross-over frequency between two genes is 7%. The distance between the two genes on a linkage map is
A. .07 units.
B. .7 units.
C. 7 units.
D. 70 units.

14. Gene expression is influenced by many factors. Which of the following is a factor in gene expression?
A. Karyotype
B. Pedigree
C. Environment
D. Phenotype

15. Two parents have the genotype Gg for a genetic disorder caused by a dominant allele. What is the chance that any of their children will inherit the disorder? (Hint: complete a Punnett square cross on a separate piece of paper.)
A. 25%
B. 50%
C. 75%
D. 100%

16. Human height occurs in a continuous range because it is affected by the interaction of several genes, making it a(n)
A. autosomal trait.
B. sex-linked trait.
C. polygenic trait.
D. codominant trait.

17. The gene linkage map shown in Figure 7.2 shows the order of genes A, B, and C. Which of the following statements about the genes is true?
A. The distance between A and B is 14.5 map units.
B. A and B cross over 2.5% of the time.
C. A and C are linked 8.5% of the time.
D. B and C are most likely to be inherited together.

18. Two genes cross over 6% of the time. This percentage means that the genes are
A. inactivated in 6 out of 100 offspring.
B. incompletely dominant in 6 out of 100 offspring.
C. not inherited together in 6 out of 100 offspring.
D. on *** chromosomes in 6 out of 100 offspring.

19. Suppose a person is a carrier for a genetic disorder. Which of the following phrases about this person is true?
A. Does not have the disorder but can pass it on
B. Will develop the disorder only late in life
C. Cannot pass the disorder to sons, just daughters
D. The allele is not passed on due to Y chromosome inactivation

20. What is the main reason that sex-linked disorders are most often observed in males?
A. The X chromosome only has genes for genetic disorders.