17. A testcross A.is used to determine if an organism that is displaying a recessive trait is heterozygous or homozygous for that trait. B.

Transcription

1 ch04 Student: 1. Which of the following does not inactivate an X chromosome? A. Mammals B. Drosophila C. C. elegans D. Humans 2. Who originally identified a highly condensed structure in the interphase of nuclei? A. Lyon B. Barr and Bertram C. Ohno D. None of these choices are correct 3. What gene is encoded in the Xic? A. Xce B. Xist C. TsiX 4. What gene is most responsible for X-inactivation? A. Xic B. Xist C. TsiX D. Xce 5. How many Barr bodies would an individual with a XXY genotype possess? A. 0 B. 1 C. 2 D. None of these choices are correct 6. The coat color of calico cats is a result of. A. maternal inheritance B. X-inactivation C. imprinting D. extra nuclear inheritance 7. The Lyon hypothesis attempts to explain the molecular mechanism of. A. X-inactivation B. genomic imprinting C. maternal inheritance D. extra nuclear inheritance 8. Dosage compensation offsets the problems associated with differences in the number of chromosomes in many species. A. sex B. autosome C. somatic D. nuclear

2 9. The genetic control of X-inactivation is governed by a short region on the X chromosome called the. A. Y-inactivation center (Yic) B. condensation center C. X-inactivation center (Xic) D. X-initiation center 10. During sexual reproduction, each parent contributes one set of chromosomes. Similar chromosomes from each parent are called. A. karyotypes B. sister chromatids C. homologues D. sex chromosomes 11. Studies of X-linked inheritance and sex chromosomes provided the evidence for which of the following? A. Chromosomal theory of inheritance B. Particulate theory of inheritance C. Theory of natural selection D. Law of segregation E. Principle of dominance 12. In humans, which sex is considered to be the heterogametic sex? A. Male B. Female 13. In a Z-W system, which is considered to be the homogametic sex? A. Males B. Females 14. A male is produced from an unfertilized haploid egg is an example of what type of sex determination system? A. X-Y B. Z-W C. X-O D. Haplo-diploid E. None of these choices are correct 15. The first person to experimentally determine that a trait is located on a specific chromosome was. A. Mendel B. Boveri and Sutton C. Weissman D. Morgan and Bridges E. None of these choices are correct 16. If a gene is located on the X chromosome, but not the Y, it is said to be an example of. A. autosomal inheritance B. sex-linkage C. reciprocal cross D. pseudoautosomal inheritance E. holandric

3 17. A testcross A.is used to determine if an organism that is displaying a recessive trait is heterozygous or homozygous for that trait. B. results in the F2 generation having a phenotypic ratio of 1/2 dominant to 1/2 recessive. C is used when an individual with a dominant phenotype and unknown genotype is crossed to an. individual with a recessive phenotype. D. results in offspring that always display the recessive phenotype. 18. Sex determination in humans and Drosophila is similar in the fact that A. the ratio of X chromosomes to sets of autosomes determines maleness or femaleness in both. B. males in both will always have one Y chromosome, whereas females will not have a Y chromosome. C. females lack X chromsomes. D. males have one X chromsome and females have two X chromosomes. 19. An example of a mechanism in which sex is determined by environmental factors is A. females are produced from fertilized eggs, whereas males are produced from unfertilized eggs. B when the male cares for the eggs, all of the offspring will be male, whereas if the female cares for the. eggs, all of the offspring will be female. C.fertilized eggs incubated at one temperature produce males, whereas eggs incubated at a different temperature produce females. D. males will have a Y chromosome, whereas females will not have a Y chromosome. 20. An human individual has a karyotype that is XY but is phenotypically female. An explanation for this could be A. a deletion of the Sry gene on the Y chromosome, thus resulting in an female phenotype. B. a translocation of the Sry gene to one of the X chromosomes has occured, thus resulting in a female phenotype. C. the Sry gene has been amplified 10 fold on the Y chromosome. D. sex is determined by genes located on autosomes, not sex chromosomes. 21. Brown spotting of the teeth in humans is caused by a dominant X-linked gene. If a man with normal teeth marries a woman with brown teeth who had a father with normal teeth, then of their daughters will have brown teeth. A. 100% B. 50% C. 25% D. 0% 22. Red-green colorblindness is a X-linked recessive trait in humans. If a woman who is a carrier for redgreen colorblindness marries a normal male, what percent of their sons will be colorblind? A. 100% B. 50% C. 25% D. 0% 23. Pseudoautosomal inheritance occurs when A. a gene on an autosome is silenced by inactivation. B. a gene on a Y chromosome has the same inheritance pattern as a gene on a X chromosome. C. a gene on an autosome has the same inheritance pattern as a gene on a sex chromosome. D. a gene on a sex chromosome has the same inheritance pattern as a gene on an autosome. 24. Flowering plants will produce flowers that are dioecious, meaning that the male and female parts are contained within the same flower. True False 25. A calico cat will always be female. True False

4 1. B ch04 Key 2. B 3. B 4. B 5. B 6. B 7. A 8. A 9. C 10. D 11. A 12. A 13. A 14. D 15. D 16. B 17. C 18. D 19. C 20. A 21. B 22. B 23. D 24. FALSE 25. TRUE

5 ch04 Summary Category # of Questions Bloom's Level: 1. Remember 10 Bloom's Level: 2. Understand 10 Bloom's Level: 3. Apply 4 Bloom's Level: 4. Analyze 1 Chapter - Chapter Learning Outcome: 04.01: Recognize the different methods of sex determination. 7 Learning Outcome: 04.02: Understand the phenomenon of dosage compensation and know its molecular basis. 10 Learning Outcome: 04.03: Differentiate between X-linked, Y-linked, and pseudoautosomal genes. 4 Learning Outcome: 04.04: Distinguish between the various patterns of inheritance related to sex. 1 Learning Outcome: 04.05: Understand the importance of Morgan's work as a proof of the chromosomal theory of inheritance. Section: Section: Section: Section: Topic: Inheritance 25 3