MULTIPLE CHOICE QUESTIONS

Transcription

1 SHORT ANSWER QUESTIONS-Please type your awesome answers on a separate sheet of paper. 1. What is an X-linked inheritance pattern? Use a specific example to explain the role of the father and mother in this unique inheritance pattern and note the differential impact on male and female offspring. 2. What is dosage compensation with respect to the sex chromosomes, and how is this accomplished in humans? 3. What is the role of heterozygote advantage in maintaining high frequencies of mutant alleles in populations? MULTIPLE CHOICE QUESTIONS 1. Colchicine is a drug that: A. arrests cells in mitotic telophase. B. stimulates meiosis. C. prevents DNA replication. D. arrests cells in mitotic metaphase. E. prevents cells from entering prophase Use the figure to answer the corresponding questions. 2. Based on the phenotypes of the third generation, the genotype of the father in the second generation must be: A. homozygous for albinism. B. heterozygous for hair color. C. heterozygous for albinism. D. X-linked. E. dominant. 3. The genotypes of the normal females in the second generation in the accompanying figure are: A. homozygous for albinism. B. heterozygous for hair color. C. heterozygous for albinism. D. X-linked. E. unknown. 16-1

2 4. The inheritance pattern demonstrated by the pedigree in the associated figure is: A. autosomal recessive. B. autosomal dominant. C. X-linked recessive. D. X-linked dominant. E. unknown from these data. 5. In genomic imprinting: A. a gene is imprinted with the phenotype of the parent, passing it to a progeny. B. the expression of a gene depends on the parental phenotype. C. a gene is imprinted with the age of the parent, passing it to the progeny. D. the expression of a gene depends on which parent it is inherited from. E. None of these. 6. An individual who inherited the specific chromosome deletion from the would most likely have Prader-Willi syndrome rather than Angelman syndrome. A. 15; mother B. 15; father C. 21; mother D. 21; father E. None of these. 7. About what percentage of the human DNA codes for polypeptides? A. 2% B. 5% C. 8% D. 50% E. 86% 8. Autosomal aneuploidies arise by: A. chromosome breakage and rejoining. B. nondisjunction. C. errors in crossing-over. D. mistakes in chromosome replication. E. mutations. 9. The sperm in the figure below were most likely produced by: A. nondisjunction. B. mutation. C. X-linkage. D. translocation. E. normal meiosis. 10. Turner syndrome is an example of a condition. A. monosomic B. disomic C. trisomic D. polyploid E. fragile site 16-2

3 11. Autosomal monosomy is not seen in live births because: A. its effects are so small as to be overlooked. B. its effects do not set in until adulthood. C. its effects are so lethal as to cause spontaneous abortion early in pregnancy. D. it only occurs in sex chromosomes and therefore does affect nonreproductive function. E. None of these. 12. Persons having an XO karyotype are sterile females. They have syndrome. A. Turner B. Klinefelter C. Down (trisomy form) D. Phenylketonuria E. Down (translocation form) 13. Down syndrome is an example of a condition. A. monosomic B. disomic C. trisomic D. polyploid E. transgenic 14. Which of the following statements concerning Down syndrome is FALSE? A. Down syndrome involves nondisjunction. B. Down syndrome individuals have 47 chromosomes per somatic cell. C. Down syndrome incidence increases with increasing maternal age. D. Down syndrome individuals have an extra chromosome 22. E. Down syndrome is variable in expression. 15. Aneuploidies for the sex chromosomes are more viable because: A. they carry less information that most chromosomes. B. of a lack crossing-over between the X and the Y. C. they are smaller than most chromosomes. D. their information is carried on other chromosomes. E. of dosage compensation. 16. Persons having an XXY karyotype are nearly normal males but produce few or no sperm. They have syndrome. A. Turner B. Klinefelter C. Down (trisomy form) D. Phenylketonuria E. Down (translocation form) 17. A karyotype reveals that an individual is XYY. Based on your knowledge of human genetics you correctly conclude that this individual is phenotypically and. A. female; with criminal tendencies B. female; sterile C. female; fertile D. male; sterile E. male; fertile 16-3

4 18. Translocation occurs when: A. part of a chromosome breaks off and attaches to a nonhomologous chromosome. B. part of a chromosome breaks off and attaches to a homologous chromosome. C. crossing-over events occur. D. genes move from one area on a chromosome to another area on the same chromosome. E. a Y chromosome replaces an X chromosome in a female cell. 19. Cri du chat syndrome arises from: A. trisomy for chromosome 5. B. deletion of part of chromosome 5. C. a 14/21reciprocal translocation. D. nondisjunction. E. a duplication of part of chromosome Which of the following statements about fragile X syndrome is not correct? A. It results in learning and attention disabilities in males. B. It results in hyperactivity in males. C. The location of the fragile X site is exactly the same in all of an individual s cells. D. It results in the formation of shorter-than-normal sequences of CGG. E. Females are usually heterozygous and are therefore more likely to have a normal phenotype. 21. Which of the following are inborn errors of metabolism? A. PKU and alkaptonuria B. sickle cell anemia and hemophilia C. cystic fibrosis and Tay-Sachs disease D. Huntington s disease and fragile X syndrome E. cri-du-chat syndrome and Down syndrome 22. Why are most infants with phenylketonuria usually healthy at birth? A. The defect causing the condition has usually been repaired by that time. B. The mother breaks down phenylalanine for both herself and her fetus. C. The infant can produce sufficient quantities of the enzymes needed by birth. D. Phenylalanine can be completely excreted in infants. E. Phenylalanine is completely metabolized in infants. 23. Maternal PKU can result in serious effects in fetuses. This problem occurs because: A. the fetus is homozygous for PKU and therefore cannot metabolize phenylalanine. B. the fetus is usually homozygous dominant and therefore has PKU. C. the mother is heterozygous for PKU and therefore cannot metabolize phenylalanine. D. the mother is homozygous dominant for PKU and cannot metabolize phenylalanine. E. the mother is homozygous recessive and cannot metabolize phenylalanine. 24. Individuals who are for sickle cell hemoglobin tend to be resistant to falciparum malaria, but do not experience the effects of sickled red blood cells. A. homozygous dominant; more B. homozygous dominant; less C. homozygous recessive; less D. heterozygous; more E. heterozygous; less 16-4

5 25. Which of the following statements about the abnormal mucous production associated with cystic fibrosis is correct? A. The mucus blocks the action of the cilia that line the bronchi. B. The mucus promotes the growth of dangerous bacteria in the respiratory system. C. The mucus is in the respiratory system is abnormally viscous. D. Abnormal mucous secretions occur throughout the body systems. E. All of these. 26. The selective advantage linked to the high frequency of the cystic fibrosis allele in Caucasians is: A. an increased resistance to falciparum malaria. B. the prevention of excessive water loss associated with certain types of diarrhea. C. production of an enzyme to break down cholera toxin. D. increased mucous secretions for the removal of infectious cells. E. an increased probability of Salmonella infection. 27. Tay-Sachs disease is a(n) disease that results in blindness, mental retardation, and death due to. A. sex-linked; the absence of one of the sex chromosomes B. autosomal recessive; accumulation of lipids in brain cells C. X-linked; accumulation of lipase in cells of sweat glands D. autosomal; the inability to break down amylase in the intestines E. autosomal dominant; accumulation of mucus in the lungs 28. What factor allows the dominant mutant allele for Huntington s disease to persist in human populations despite its devastating effects? A. Heterozygote advantage. B. The fact that its symptoms do not typically show until after the individual has had children. C. Its effects are not expressed in heterozygous individuals. D. Its effects are only expressed in homozygous recessive individuals. E. Its effects are only expressed in homozygous dominant individuals. 29. Hemophilia A is an example of disease and is characterized by a lack of blood-clotting factor. A. an X-linked; VIII B. a sex-linked recessive; V C. an autosomal dominant; VIII D. a sex-linked dominant; V E. an autosomal recessive; VIII 30. A couple in which the woman is homozygous dominant and the man has hemophilia A will produce: A. carrier daughters and affected sons. B. affected daughters and affected sons. C. carrier daughters and normal sons. D. normal daughters and normal sons. E. offspring of unknown genotype for this gene. 31. Which of the following must be true for a female to inherit hemophilia? A. Her father has the disease. B. Her mother is homozygous normal. C. Her father and mother are heterozygous. D. Her mother has the disease. E. Her father is heterozygous. 16-5

6 32. What are the predicted phenotypes of the children from a union of a woman who is heterozygous for hemophilia and a man who is normal? (Use the Punnett square to verify your answer.) A. 100% normal B. 75% hemophilia: 25 % normal C. 50% hemophilia: 50% normal D. 25 % hemophilia: 75% normal E. 100% hemophilia 33. Gene therapy is: A. replacing all mutant alleles in body cells. B. replacing poor copies of alleles with normal alleles. C. replacing a mutant allele in certain body cells with a normal allele. D. repairing mutant alleles in certain body cells. E. improving gene expression in key body cells. 34. The current status of gene therapy is: A. it is currently being used effectively to cure cystic fibrosis. B. it has been terminated because clinical trials have shown that it is ineffective. C. it is being evaluated to assess the risks associated with potential side effects. D. the number of clinical trials is increasing at an almost uncontrolled rate. E. that it may be considered in the future, but currently the technology is not available. 35. An advantage of chorionic villus sampling (compared with amniocentesis) is that: A. chorionic villus sampling detects a much wider range of genetic defects than does amniocentesis. B. chorionic villus sampling is much less expensive than is amniocentesis. C. chorionic villus sampling is much less invasive than amniocentesis. D. chorionic villus sampling is much easier to perform than amniocentesis. E. chorionic villus sampling can be performed much earlier than can amniocentesis. 36. Genetic screening can be used to identify all of the following except: A. PKU. B. Tay-Sachs disease. C. Huntington s disease. D. sickle cell anemia. E. None of these; all can be identified using genetic screening techniques. 37. Which statement is true regarding the ethical considerations surrounding human genetics? A. Genetic discrimination is not a concern in the US with the scant genetic information known now. B. Genetic discrimination is not possible when all the genetic information and its effects are known. C. In the current ethical climate genetic privacy is not a significant concern. D. Consanguineous matings increase the chances of the inheritances of autosomal recessive alleles. E. Insurance companies have no arguments for wanting genetic information on their policy holders. 16-6