OE compilations OE COMPILATIONS (Opoku Emmanuel) KWAME NKRUMAH UNIVERSITY OF SCIENCE & TECHNOLOGY COLLEGE OF SCIENCE –DEPT OF THEORETICAL & APPLIED BIOLOGY RESIT Examinations, 2012/2013 1st Year Biology, Biochemistry, Human Biology, Dentistry & Veterinary Medicine Biol. 153 SEPTEMBER 2013 NOTE: Basic & Medical Genetics 1 THREE HOURS YOU ARE FREE TO TAKE THE QUESTION PAPER AWAY FROM THE EXAMINATION HALL . Attempt As many Questions as your planned time will allow you, in BOTH SECTIONS 1 and 2. You will NOT be prompted to move between sections. Sections 1 & 2 must be answered using the scannables. Answer each section OE compilations OE compilations on the scannable you have appropriately labelled in pencil as SECTIONS 1 AND 2 at the bottom. CAREFULLY WRITE AND SHADE IN YOUR INDEX NUMBER AND COURSE CODE P.S. Please if you perceive a mistake in a question or you think a particular question is not understood, QUICKLY MOVE ON TO THE NEXT. Do not disrupt the rhythm of the class by asking the invigilator for corrections. Adequate provisions are made for such anomalies in the final evaluation. DO NOT BOTHER THE INVIGILATOR WITH ANY QUESTIONS. ALL QUESTIONS CARRY EQUAL MARKS so work speedily through the questions. SECTION I 1. .Which of the following represent the possible genotypes resulting from a cross between two individuals that are heterozygous for black hair (Bb)? a) BB and Bb b) BB, Bb and bb c) BB only d) Bb only e) bb only 2. Which of the following represent the possible genotypes resulting from a cross between an individual homozygous for black hair (BB) and an individual homozygous for blonde hair (bb)? a) BB and Bb b) BB, Bb and bb c) BB only d) Bb only e) bb only 3. Heterozygosity can be determined by: a) the appearance of the individual. b) the appearance of the parents. OE compilations OE compilations c) d) e) 4. a) b) c) d) e) 5. a) b) c) d) e) 6. a) b) c) d) e) 7. a) b) c) d) e) 8. a) b) c) d) e) 9. a) a test cross of the unknown individual with a homozygous individual. both a and b both band c What is the probability that two lizards that are heterozygous for stripes on their tails (Ss) will produce an offspring that is homozygous for no stripes (ss)? They will always produce offspring that are homozygous for no stripes. The probability is 1/2 that they will produce offspring homozygous for no stripes. The probability is 1/4 that they will produce offspring homozygous for no stripes. The probability is 1/8 that they will produce offspring homozygous for no stripes. They will never produce offspring homozygous for no stripes. For which of the following can the laws of probability be applied? To predict the chances of winning the lottery. To predict the chances of producing a female child. To predict the chances of producing a male child. All of the above. None of the above. If brown eyes are dominant over blue eyes and two brown eyed individuals have a child with blue eyes then that means: both parents are homozygous for brown eyes. both parents are heterozygous for brown eyes. there is a 3/4 chance that their second child will have brown eyes. there is a 50/50 chance that their second child will have blue eyes. none of the above are true. Two Martians fall in love and get married. One Martian is homozygous for red eyes (RR) while the other is heterozygous for red eyes (Rr). The recessive eye color is purple. What are the chances that they will have a child with purple eyes? 1/1 ½ ¼ ¾ 0 What are the chances that the alien couple will have a child with red eyes? 1/1 ½ ¼ ¾ 0 What are the chances that the alien couple will have a child that is heterozygous for eye color? 1/1 OE compilations OE compilations b) ½ c) ¼ d) ¾ e) 0 10. What are the chances that the alien couple will have a child that is homozygous for red eyes? a) 1/1 b) ½ c) ¼ d) ¾ e) 0 11. The probability that two genes will be separated by crossing over is related to: a) the trait that they control. b) the distance between the gene and the centromere. c) the distance between them on the chromosome. d) Both a and b e) Both band c 12. Genes that tend to be inherited together are said to be: a) associated. b) related. c) similar. d) linked. e) alleles. 13. Human females have two X chromosomes, a condition which is referred to as: a) a sex-linked trait. b) dominant chromosome sex determination. c) homogametic. d) heterogametic. e) none of the above. 14. Why are slightly more male children born than are females? a) X-bearing sperm are less likely to survive spermatogenesis. b) Y-bearing sperm must have some competitive advantage over X-bearing sperm. c) More Y-bearing sperm are produced. d) All of the above are true. e) None of the above are true. 15. When pink-flowered plants were crossed they produced red-flowered, pink-flowered, and white-flowered plants in a ratio of 1:2:1. This is an example of: a) variegation. b) hybrid vigor. c) incomplete dominance. OE compilations OE compilations d) epistasis. e) a polygenic trait. 16. Breeding a yellow dog to a brown dog produced mixed color puppies (with both yellow and brown hairs). This is an example of : a) variegation. b) codominance c) incomplete dominance. d) epistasis. e) a polygenic trait. 17. _____ refers to a situation in which several pairs of alleles interact to affect a single trait. a) Variegation b) Codominance c) Incomplete dominance d) Epistasis e) None of the above 18. The mating of totally unrelated strains is called _____ and often results in improvement that is called ______ a) inbreeding, epistasis b) outbreeding, hybrid vigor c) outbreeding, hybrid breakdown d) inbreeding, hybrid vigor e) none of the above 19. The antiparallel nature of DNA is best explained by which of the following? a) The two strands run in opposite directions; each has an exposed 5' phosphate on one end and exposed 3' hydroxyl group on the other. b) The two strands run in the same direction, making it a simple matter to copy an identical but antiparallel strand of RNA. c) The bases are antiparallel to the long axis of the molecule. d) Both a and c are true. e) None of the above are true. 20. ____ hydrogen bonds can form between guanine and cytosine while hydrogen bonds form between adenine and thymine. a) 1; 2 b) 2; 3 c) 3; 4 d) 4; 3 e) 3; 2 21. Erwin Chargaff and coworkers determined that: a) The ratio of purines to pyrimidines is not far from one. OE compilations OE compilations b) The ratio of adenine to thymine is not far from one. c) The ratio of guanine to cytosine is not far from one. d) All of the above are true. e) None of the above. 22. Why don't adenine and cytosine hydrogen bond with each other? a) They are antiparallel and are not attracted to each other. b) The pairing of adenine and cytosine does not lead to favorable hydrogen bonding c) Adenine is a purine and cytosine is a pyrimidine. d) Both a and b are true. e) Both band c are true. 23. What evolutionary advantage is provided by meiosis? a) Genetic diversity. b) Sexual dimorphism. c) Diploidy. d) Polyploidy. e) None of the above. 24. A woman is diagnosed to have the genetic disease known as Huntington's disorder. It is a rare defect caused by an autosomal dominant allele. The chance for anyone of her children to inherit the disease is a) dependent on the sex of the child. b) 1/3 c) ½ d) ¾ 25. Karyotyping is useful for determining: a) the number of chromosomes in an individual. b) if recessive traits are present. c) if a specific gene is missing from a chromosome. d) if gene mutations have occurred. e) Both c and d are true. 26. The correct number of chromosomes is maintained in higher species by: a) A process by which one-half of the chromosomes in gametes are removed. b) Chromosome reduction in the newly formed zygote. c) A sexual cycle called meiosis which reduces the chromosome number by half. d) Both a and b are true. e) Both band c are true. 27. How do plant cells differ from animal cells during mitosis? a) Plant cells lack spindle fibers. b) Animal cells have a pair of centrioles in the middle of each microtubule-organizing center. c) Plant cells lack centrioles in their microtubule-organizing centers. OE compilations OE compilations d) Both a and b are true. e) Both band c are true. 28. What role do centrioles play in spindle formation in animal cells? a) They probably do not play a role in spindle formation in animal cells. b) They organize the correct arrangement of spindle fibers to ensure the correct distribution of chromosomes. c) Centrioles initiate activity in the aster. d) Centrioles provide the ATP to fuel spindle formation. e) None of the above are true. 29. During mitosis nucleoli disappear during ___ and again become apparent during. a) metaphase, anaphase b) prophase, anaphase c) prophase, telophase d) interphase, telophase e) anaphase, telophase 30. The kinetochore serves which of the following functions? a) The kinetochore anchors spindle fibers to centrioles. b) The kinetochores are the site of rRNA synthesis. c) Kinetochores regulate the length of the cell cycle. d) Kinetochores attach to the centromere of chromosomes during mitosis. e) Both band c are true. 31. In an autosomal dominant disorder such as Huntington's, two carrier parents have the probability of passing the gene on to _____ percent of their children. a) 50 b) 0 c) 100 d) 25 e) 75 32. How does the replication of cellular organelles relate to the cell cycle? a) Organelles replicate at roughly the same time as do the chromosomes. b) Organelles replicate during interphase and are apportioned more or less between the daughter cells. c) Organelles contain their own chromosomes that undergo a mitosis of their own while the cell is dividing. d) None of the above are true. e) Both a and c are true. 33. An organism with a diploid number of 36 chromosomes will have ____ chromosome in their gametes and _____ chromosomes in their somatic cells. a) 18, 18 b) 18, 36 OE compilations OE compilations c) 36, 18 d) 36, 36 e) 36, 72 34. What role has polyploidy played in plant evolution? a) Polyploidy has allowed plants to omit the process of chromosome reduction during meiosis. b) Polyploidy plants are often larger and more hardy than are diploid plants. c) Polyploidy allows crossing to occur between unrelated species of plants. d) None of the above are true. e) Both a and c are true. 35. Constant chromosome number is ensured in sexually reproducing species by: a) Mitosis b) Meiosis c) Fertilization d) Both a and b are true. e) Both band c are true. 36. During S phase of the cell cycle, which of the following take place? a) Organelles are replicated. b) DNA is replicated. c) Chromosomal proteins are replicated. d) A cell plate is synthesized. e) Both band c are true. 37. Which of the following are produced by meiosis? a) polar bodies b) eggs c) sperm d) fungal spores e) All of the above. 38. The complex formed between a maternal homologue and a paternal homologue is called a (n): a) bivalent b) tetrad c) synaptonemal complex d) sister chromatid e) Either a or b 39. Why is prophase I longer during the formation of egg cells in some species? a) Prophase I involves chromosomal replication and therefore takes longer than prophase II. b) Prophase I involves chromosomal reduction and therefore takes longer than prophase II. c) The cell grows and synthesizes nutrients required by the future embryo during prophase I. OE compilations OE compilations d) None of the above are true. e) Both a and c are true. 40. When does crossing over occur? a) during interphase b) during prophase I c) during metaphase I d) during prophase II e) during metaphase II 41. During prophase I, each chiasmata represents: a) the site at which homologous chromosomes are united b) the site at which maternal and paternal homologues are united c) a newly formed haploid gamete d) a site of crossing over e) None of the above 42. During which of the following stages of meiosis do the chromatids separate? a) metaphase I b) anaphase I c) metaphase II d) anaphase II e) telophase II 43. _____ egg(s) are formed by oogenesis and ____ sperm (s) are formed by spermatogenesis. a) 4, 4 b) 1, 1 c) 4, 1 d) 1, 4 e) 2, 2 44. Heredity is based on which of the following? a) A complex mechanism used to precisely copy DNA. b) A mechanism by which genetic information is distributed to offspring. c) A mechanism by which only the most desirable traits are passed to offspring. d) All of the above are true. e) Only a and b are true. 45. Which of the following phenomena are exceptions to Mendel's principles? a) linkage b) sex linkage c) polygenic inheritance d) all of the above e) none of the above OE compilations OE compilations 46. During prophase I of meiosis, homologous chromosomes lie side by side. This phenomenon is known as: a) homologue pairing b) synapsis c) tetrad formation d) paternal pairing e) None of the above. 47. Which of the following is/are required to study inheritance? a) spring pollinating plants b) genetic variation c) true breeding lines d) both a and b are true e) both band c are true 48. Which of the following represent the possible genotypes resulting from a cross between an individual homozygous for black hair (BB) and an individual heterozygous for black hair (Bb)? a) BB and Bb b) BB, Bb and bb c) BB only d) Bb only e) bb only 49. Why is a DNA molecule able to store large amounts of information? a) It contains a large number of different nucleotides. b) Its nucleotides can be arranged in a large number of possible sequences. c) It is capable of assuming a wide variety of shapes. d) Both a and b are true. e) Both a and c are true. 50. How is a single strand of DNA able to serve as a template for another strand? a) The complementary pairing of nucleotides means that nucleotides would pair with those of the original strand to form a new strand. b) Hydrogen bonds holding the two strands together would be easy to break allowing a single strand to serve as a template. c) A single strand of DNA is not able to serve as a template. d) One strand of DNA directs the synthesis of a new strand on its partner. e) Both a and b are true. 51. Which of the following is the best definition of semi-conservative replication? a) The translation of a DNA molecule into a complementary strand of RNA. b) The fact that a DNA molecule consists of one parental strand and one new strand. c) The fact that the number of DNA molecules is doubled with every other replication. d) Both a and b are true. OE compilations OE compilations e) None of the above are true. 52. Why does DNA synthesis only proceed in the 5'→ 3' direction? a) Because DNA polymerases can only add nucleotides to the 3' end of a polynucleotide strand. b) Because the 3' end of the polynucleotide molecule is more electronegative than the 5' end. c) Because that is the direction in which the two strands of DNA unzip. d) Because that is the only direction that polymerases can be oriented. e) None of the above are true. 53. The DNA strand that is replicated smoothly and continuously is called the: a) primary strand. b) first strand. c) leading strand. d) alpha strand. e) None of the above. 54. A replication fork: a) is only seen in prokaryotic chromosomes. b) is only seen in eukaryotic chromosomes. c) is a Y-shaped structure where both DNA strands are replicated simultaneously d) Both a and b are true. e) Both band c are true. 55. Each Okazaki strand is initiated by: a) the same RNA primer that began synthesizing on the leading strand. b) RNA polymerase. c) DNA polymerase d) a separate RNA primer. e) None of the above. 56. Okazaki fragments are joined together by: a) RNA polymerase b) DNA ligase c) DNA polymerase d) RNA ligase e) None of the above. 57. Nucleosomes are best described as: a) eukaryotic DNA associated with histone proteins. b) prokaryotic DNA associated with nonhistone proteins. c) eukaryotic DNA associated with nonhistone proteins. d) prokaryotic DNA associated with histone proteins. e) None of the above. 58. Densely staining regions of highly compacted chromatin in the chromosome are called: a) heterochromatin. OE compilations OE compilations b) homochromatin. c) histone dependent chromatin. d) primary chromatin. e) None of the above. 59. Heterochromatin: a) is darkly staining chromatin that is generally not transcribed. b) is the portion of chromatin that is transcribed into a functional gene product. c) contains the sequences that are required to regulate translation. d) contains the sequences that are required to regulate transcription. e) None of the above are true. 60. Which of the following types of processing does eukaryotic mRNA undergo before it is functional? a) Splicing b) Capping c) Polyadenylation d) All of the above e) None of the above. 61. Proteolytic processing of eukaryotic proteins involves: a) removal of a portion of the polypeptide chain from an inactive precursor form of the protein. b) the addition of one or functional groups to a precursor protein. c) the removal of one or more functional groups from a precursor protein. d) Both a and b are true. e) Both band c are true. 62. Chemical modification of eukaryotic proteins involves: a) removal of a portion of the polypeptide chain from an inactive precursor form of the protein. b) the addition of one or more functional groups from a precursor protein. c) the removal of one or more functional groups from a precursor protein. d) Both a and b are true. e) Both band c are true. 63. Recombinant DNA technology has led to major breakthroughs in: a) Genetics b) Evolution c) Cell biology d) All of the above e) Only a and c are true. 64. What have bacteria contributed that is necessary for producing recombinant DNA? a) Special RNA polymerases. b) Ligases that seal prokaryotic and eukaryotic DNA segments. OE compilations OE compilations c) Restriction enzymes. d) A system in which DNA can replicate without the presence of a nuclear envelope. e) None of the above. 65. What purpose do restriction enzymes play in bacterial cells? a) Restriction enzymes prevent the overproduction of mRNA in the bacterial cell. b) Restriction enzymes attack bacteriophage DNA when it enters the cell. c) Restriction enzymes promote bonding of the promoter to the mRNA molecule. d) Restriction enzymes limit the rate of bacterial replication. e) None of the above. 66. Chromatin is made up of: a) DNA b) RNA c) protein d) All of the above e) Only a and c Human genetic traits are influenced by: a) the genes that were inherited from the organism's parents. b) the environment. c) those genes in the genome that are actually expressed. d) All of the above are true. e) None of the above are true. 67. The science of cytogenetics is: a) the study of chromosomes. b) applicable to haploid organisms only. c) involves analysis of pedigrees. d) Both a and b are true. e) None of the above are true. 68. Which of the following provides evidence that one of the X chromosomes is inactivated in mammals? a) the fact that the DNA of one of the X chromosomes in female mammals is not packaged into nucleosomes. b) the fact that one of the X chromosomes in female mammals becomes heterochromatic. c) the fact that only one of the X chromosomes in female mammals has the required promoters required for translation. d) Both a and c are true. e) Both band c are true. 69. Why is Drosophila so useful in genetics experiments? a) Because they have just a few chromosomes it is possible to relate genetic data with the number of chromosomes. OE compilations OE compilations b) Because their chromosomes are so large it is possible to relate genetic data to chromosome structure. c) Because they have such short life spans it is possible to track genetic traits over many generations. d) Because these studies have led to the development of techniques, such as karyotyping, that are useful in human genetic studies. e) All of the above are true. 70. Polyploidy: a) may be the result of more than one sperm fertilizing an egg. b) is lethal in humans. c) may be the result of the failure of chromosomes to separate during meiosis. d) Both a and b are true. e) All of the above are true. 71. The DNA strand that is replicated in a discontinuous manner is called the ____ strand and is synthesized in short pieces called _____ a) primary; leaders b) lagging; fragments c) lagging; Okazaki fragments d) Okazaki; laggers e) None of the above. 72. Aneuploidies are: a) a phenomenon that only occurs in some species of plants. b) a condition in which an extra chromosome is present or one is absent. c) a defect that is almost always fatal in humans. d) uncommon in humans. e) almost always mutations with a beneficial effect on the individual. 73. Turner syndrome is an example of a condition. a) monosomic b) disomic c) trisomic d) Both a and b e) None of the above 74. Down syndrome is an example of a _ condition. a) monosomic b) disomic c) trisomic d) Both a and b e) None of the above 75. The principle of dominance states that: a) the dominant trait shows up at least 50% of the time in the first generation. OE compilations OE compilations b) the F1 generation of a hybrid cross always exhibit dominant traits. c) one gene can mask the expression of another in a hybrid. d) all of the above are true. e) none of the above are true. 76. Every inherited feature of an organism is controlled by: a) two genes. b) two chromosomes. c) polygenic inheritance d) hybrid vigor e) none of the above 77. The principle of segregation states that: a) the separation of a species into two populations is the main mechanism of speciation. b) the genes of a pair separate before gametes are formed. c) dominant genes always remain paired during gamete formation while recessive genes separate. d) both a and b are true. e) both a and c are true. 78. The location of a particular gene on a chromosome is called a(n): a) allele. b) locus. c) trait. d) map point. e) none of the above 79. Nondisjunction during mitosis leads to: a) an individual with a clone of abnormal cells. b) an individual with all abnormal cells. c) death of the daughter cells. d) nonviable sperm. e) None of the above. 80. _____ are genes that govern the same feature, such as eye color, and occupy corresponding positions on homologous chromosomes. a) Alleles b) Loci c) Homozygotes d) Coupled traits e) None of the above 81. The mating of two individuals that carry different alleles for the same trait is called: a) a monotrait cross. b) a monohybrid cross. c) a ditrait cross. OE compilations OE compilations d) a dihybrid cross. e) none of the above. 82. Persons with a 14/21 chromosome have: a) only one normal chromosome 14. b) 14/21 of a normal human genome. c) chromosome 21 translocated onto a chromosome 14. d) only one normal chromosome 21. e) a, c, and d are true. 83. Nuclear sexing involves: a) examination of the nucleus by electron microscopy. b) examination of the nucleus for the presence of the Barr body. c) altering the sex of a cell after fertilization. d) influencing which of the X chromosomes becomes the Barr body. e) None of the above. 84. Why are sex chromosome abnormalities relatively well tolerated? a) Because of the phenomenon of dosage compensation. b) Because these abnormalities are usually acquired in an adult animal. c) Because these abnormalities usually involve minor metabolic errors. d) All of the above are true. e) None of the above are true. 85. Which of the following abnormalities is most likely to be lethal? a) X chromosome monosomy b) Autosomal monosomy c) X chromosome trisomy d) Autosomal trisomy e) None of the above 86. Persons having a 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) 87. Persons having a XO karyotype are sterile. They have ___ syndrome. a) Turner b) Klinefelter c) Down (trisomy form) d) Phenylketonuria e) Down (translocation form) 88. Nearly half of the pregnancies that end in miscarriage have: OE compilations OE compilations a) trisomy of chromosome 21. b) homozygosity for a recessive lethal allele. c) major chromosomal abnormalities. d) Klinefelter syndrome. e) None of the above 89. Most inborn errors of metabolism: a) are inherited as autosomal recessives. b) are inherited as X chromosome recessives. c) are primarily due to environmental factors. d) Both a and c are true. e) None of the above are true. 90. How do prokaryotic and eukaryotic chromosomes differ? a) Prokaryotic organisms have a single, circular DNA molecule. b) Prokaryotic organisms have a single, circular DNA molecule and one or more smaller, linear chromosomes. c) Eukaryotic organisms have more than one linear chromosome. d) Both a and b are true. e) Both a and c are true. 91. Why is color-blindness more common in males than in females? a) Because females would have to receive two copies of the recessive color blindness gene to actually express the trait. b) Because a male only need receive the recessive gene from his mother to be color-blind. c) Because color-blindness is an X-linked trait. d) All of the above. e) None of the above. 92. Why do male fruit flies increase the metabolism of their X chromosome? a) To produce the hormones required to maintain their male traits. b) To compensate for only having one copy of the genes located on the X chromosome. c) To prevent recessive genes from being expressed. d) Both a and b are true. e) Both band c are true. 93. Calico cats are never male because: a) recessive genes are not usually expressed on their only X chromosome. b) they would be sterile and therefore unable to pass on the trait. c) two different alleles for calico coat color to occur require two X chromosomes. d) all of the above are true. e) none of the above are true. 94. Which of the following best defines the word "gene"? a) A gene contains the information to control one trait such as eye color. b) A gene is a part of a DNA molecule that translates into an RNA molecule. OE compilations OE compilations c) A gene is the basic structural component of the chromosome. d) A gene is species specific and determines the sex of an individual. e) None of the above are true. 95. Palindromic sequences: a) allow scientists to determine the sequences of nucleic acids in a segment of DNA. b) consist of two DNA strands that read the same but in opposite directions. c) are two strands of DNA that read the same and are both oriented in the same direction. d) Both a and b are true. e) Both a and c are true. 96. How can two species have the same number of chromosomes yet be very different in appearance? a) Although two species may have the same number of chromosomes, they have differing structures and sizes. b) The environment in which the zygote develops will create differences in the two species. c) It is the information specified by genes on the chromosomes that makes each species unique, not the number of chromosomes. d) Both a and b are true. e) Both band c are true. 97. Chromosomes are duplicated during ___ a) G1 phase. b) G2 phase. c) S phase d) metaphase e) prophase 98. Which of the following marks the beginning of G2 phase? a) Formation of the spindle apparatus. b) Formation of a cleavage furrow. c) Increased uptake of molecular oxygen. d) Increased protein synthesis. e) The beginning of mitosis. 99. Eukaryotic chromosomes (of most species) become visible with the microscope during _____ a) anaphase b) interphase c) metaphase d) prophase e) telophase 100. How are restriction enzymes used in recombinant DNA technology? a) Restriction enzymes are used to cut DNA into shorter fragments. OE compilations OE compilations b) Restriction enzymes allow scientists to limit the quantities of mRNA that the cell produces. c) Restriction enzymes are used to join two DNA sequences. d) Both a and c are true. e) Both band c are true. 101. Why is pattern baldness more common in men than in women? a) The gene may be recessive in females due to the presence of female sex hormones. b) Because of the effect of genes on the Y chromosome. c) Because females would need to be homozygous for the trait to express pattern baldness. d) Both a and b are true. e) Both a and c are true. 102. "Sticky ends" are: a) the single-stranded end of a DNA segment that can pair with the complementary singlestranded ends of other DNA molecules that were cut with the same restriction enzyme. b) a problem in recombinant DNA technology because they can lead to the formation of loops of single stranded DNA. c) used to insert eukaryotic DNA into a prokaryotic chromosome. d) Both a and b are true. e) Both a and c are true. 103. Which of the following can be used as DNA vectors? a) Bacteriophages b) Plasmids c) E. co1i cells d) Both a and b e) Both a and c 104. Why might a scientist choose a bacteriophage rather than a plasmid to use as a DNA vector? a) Bacteriophages are easy to cultivate. b) Bacteriophages can carry larger DNA molecules than can plasmids. c) Bacteriophages are more stable as DNA vectors than are plasmids. d) Bacteriophages transmit additional characteristics to E. coli that help it adapt to the newly introduced DNA. e) None of the above are true. 105. How may recombinant DNA molecules be introduced to mammalian cells? a) By adding plasmids to the mammalian cells. b) By using engineered viruses as vectors. c) By splicing the needed genes into a mammalian chromosome using restriction enzymes. d) Both a and b are true. e) Both a and c are true. 106. Genetic probes are: OE compilations OE compilations a) radioactively labeled segments of RNA or single-stranded DNA used to identify the DNA of interest. b) Fluorescently labeled segments of mRNA that code for the protein product of interest. c) fluorescently labeled segments of single-stranded DNA used to pair with the DNA of interest. d) Both a and c are true. e) None of the above are true. 107. Hybridization involves: a) complementary base-pairing of the DNA probe with the DNA segment of interest. b) base-pairing of labeled RNA with the DNA of interest. c) base-pairing of mRNA with tRNA. d) Both a and b are true. e) None of the above are true. 108. A genomic library consists of fragments of a) all the DNA that occurs in one species. b) all the DNA contained in one chromosome. c) all the DNA that would be found in a typical cells of a particular organism. d) all the DNA in a recombinant gene. e) Both a and c are true. 109. To avoid the introduction of introns into the vector ___ is made using the enzyme __ a) sDNA, RNA polymerase b) cDNA, DNA ligase c) cDNA, reverse transcriptase d) sDNA, reverse transcriptase e) cDNA, DNA polymerase 110. How is reverse transcriptase used to clone genes? a) Reverse transcriptase is used to make a cDNA copy of an mRNA strand, thereby eliminating introns. b) Reverse transcriptase is used to make a cloned DNA copy of a plasmid DNA molecule. c) Reverse transcriptase is necessary to read the information contained on the cDNA molecule. d) Both a and b are true. e) Both b and c are true. 111. Why are the results of DNA fingerprinting sometimes ruled inadmissible in court cases? a) The DNA samples used in the technique are very small and may have been degraded. b) Even when great care is taken, the results obtained from this technique are highly variable, making it difficult to prove guilt or innocence beyond a reasonable doubt. OE compilations OE compilations c) DNA fingerprinting takes too long to perform to make it a truly useful technique. d) Both a and b are true. e) Both a and c are true. 112. How is insulin produced by genetically engineered E. coli cells superior to insulin obtained from animal sources? a) Animal insulin has a shorter life span than insulin produced using recombinant DNA techniques. b) Recombinantly produced insulin contains human rather than animal sequences, thus reducing the chances of an allergic response in the recipient. c) Animal insulin is more difficult to purify than is recombinantly produced insulin. d) All of the above are true. e) None of the above are true. 113. Which of the following have contributed to our understanding of human genetics? a) Population studies b) Pedigree analysis c) Genetic engineering technology d) All of the above e) a and b only Why are most persons with phenlyketonuria to discontinue a low phenylalanine diet by adolescence? a) The defect causing the condition has usually been repaired by that time. b) The person is usually not sensitive to phenylketones by that time. c) The person can produce sufficient quantities of the enzymes needed to convert phenylketones into tyrosine by then. d) All of the above are true. e) None of the above are true. 114. The effects of maternal PKU: a) can often be prevented if the PKU mother follows a low phenylalanine diet during pregnancy. b) can occur in the fetus of a woman who has PKU. c) can occur even though the fetus is heterozygous for PKU. d) All of the above are true. e) None of the above are true. 115. The defect that results in sickle cell anemia is: a) an amino acid substitution in hemoglobin. b) the inability of the body to produce hemoglobin. c) the inability of hemoglobin to dissolve oxygen. d) the inability of hemoglobin to release oxygen. e) None of the above 116. When a cell undergoes mitosis, OE compilations OE compilations a) the daughter cells have identical genes. b) the daughter cell has genes identical to those of the mother cell that produced it. c) the amount of cytoplasm in the mother cell and in each of the daughter cells is equal. d) there is an exact duplication and division of all of the organelles between daughter cells. e) both a and b, but not c or d 117. Which of the following is NOT an example of a clone? a) a pair of identical twins b) a group of rooted plant cuttings from a single plant c) the cells produced by the asexual reproduction of a single-celled organism d) the offspring produced by a single set of parents e) all of the above 118. Which of the following statements is true? a) Once a person reaches maturity, cell division stops unless it is to repair a wound. b) Cell division in an adult signifies cancer. c) Some specific cells throughout the body retain the ability to divide and replace themselves. d) Growth continues on throughout the life of an adult human. e) All cells retain the ability to divide even after the organism reaches maturity. 119. Strictly speaking, mitosis and meiosis are divisions of the a) nucleus. b) cytoplasm. c) chromosomes. d) only a and c e) a, b, and c 120. Eukaryotic DNA molecules a) have no proteins. b) have small amounts of protein at each end of the DNA molecules. c) have large amounts of protein at each end of the DNA molecules. d) have small amounts of protein dispersed among the DNA molecules. e) have large amounts of protein dispersed among the DNA molecules. 121. Which process is absolutely necessary for sexual reproduction to occur in a life cycle but is not necessarily required for organisms that only reproduce asexually? a) prokaryotic fission b) mitosis c) meiosis d) cytokinesis e) karyokinesis 122. Chromatids that are attached at the centromere are called what kind of chromatids? a) mother OE compilations OE compilations b) daughter c) sister d) programmed e) either a or b, but not c or d 123. The number of DNA molecules present in a duplicated chromosome is a) 1 b) undetermined. c) half that of an unduplicated chromosome. d) 2. e) 4. 124. In which of the stages below does each chromosome consist of two DNA molecules? I. metaphase III. prophase II. telophase IV. anaphase a) III and IV b) I, III, and IV c) I and III d) I, II, and III e) I, II, III, and IV 125. When a eukaryotic cell divides, the daughter cells a) manufacture all the organelles from material in the cytoplasm. b) receive enough of the organelles to start up the new cells and produce additional organelles as needed. c) produce individual organelles that attach to the spindle fibers and are distributed just like chromosomes. d) produce an equal number of organelles distributed to each cell. e) get cellular organelles by an unknown process. 126. The chromatids detach from one another and become visibly separate chromosomes during a) anaphase. b) metaphase. c) interphase. d) prophase. e) telophase. 127. The entire process of producing two cells from one cell a) starts with prophase. b) ends with cytokinesis. c) results in the equal distribution of organelles between cells. d) occurs only in multicellular organisms. OE compilations OE compilations e) both a and b, but not c or d 128. Which of the following will NOT develop into a gamete? a) spermatogonium b) polar bodies c) oocyte d) spermatid e) secondary spermatocyte 129. Polar bodies a) are dumping places for excess genetic material. b) have no known biological function. c) are produced by meiosis. d) will serve as the gametes if something happens to the egg. e) all but d are correct 130. Sperm are formed from the direct maturation of a) sperm mother cells. b) spermatids. c) spermatogonial cells. d) primary spermatocytes. e) secondary spermatocytes. 131. The mature ovum is produced by maturation of the a) oogonium. b) primary oocyte. c) secondary polar body. d) polar body I. e) none of the above 132. Which of the following genotypes is homozygous? a) AaBB b) aABB c) aaBB d) aaBb e) AaBb 133. The most accurate description of an organism with genotype AaBb is a) homozygous dominant. b) heterozygous. c) heterozygous dominant. d) homozygous recessive. e) heterozygous recessive. 134. Gene A occurs on chromosome #5, gene B occurs on chromosome #21. Therefore, these two portions of the chromosomes CANNOT be a) genes. OE compilations OE compilations b) dominant. c) loci. d) alleles. e) recessive. 135. Which organism did Mendel utilize to work out the laws of segregation and independent assortmen a) the fruit fly b) Neurospora c) the garden pea d) the chicken e) E. coli 136. Mendel's study of genetics differed from his contemporaries' studies because he a) used only pure-breeding parents. b) examined several different traits at the same time. c) kept careful records and analyzed the data statistically. d) worked on plants rather than animals e) confirmed the blending theory of inheritance. 137. The chromosomes are moving to opposite poles during a) anaphase. b) metaphase. c) interphase. d) prophase. e) telophase. 138. Who proposed the law of independent assortment? a) Morgan b) Mendel c) Sturtevant d) Weismann . e) Flemming 139. Which of the following descriptions of Mendel is INCORRECT? a) He was simply lucky to work out the laws of genetics. b) He focused on contrasting phenotypic characteristics. c) He demonstrated that the blending theory of inheritance was wrong. d) He kept exact mathematical data and was the first scientist to utilize numerical analysis of results. e) He was a monk, a science teacher, and a gardener. 140. Which of the following is NOT associated with meiosis? a) reduction of number of chromosomes b) somatic cells c) sexual reproduction OE compilations OE compilations d) sperm and egg e) germ cells 141. Which of the following statements about Mendel is false? a) He did not know about chromosomes. b) He was not aware of Darwin's theory of evolution. c) He was well trained in agriculture and mathematics. d) His work was widely recognized even though it did not produce as much controversy as Darwin's work. e) His work established a basic understanding of the laws of heredity. 142. Mendel found that pea plants expressing a recessive trait of a trait. a) were pure-breeding. b) appeared only in the first generation of a cross between two pure-breeding plants expressing contrasting forms c) disappeared after the second generation. d) could be produced only if one of the parents expressed the recessive trait. e) none of the above 143. Hybrid organisms produced from a cross between two pure-breeding organisms belong to which generation? a) PI b) HI c) AI d) FI e) F2 144. If R is dominant to r, the offspring of the cross of RR with rr will a) be homozygous. b) display the same phenotype as the RR parent. c) display the same phenotype as the rr parent. d) have the same genotype as the RR parent. e) have the same genotype as the rr parent. 145. If short hair (L) is dominant to long hair (l), animals LL and Ll have the same a) parents. b) genotypes. c) phenotypes. d) alleles. e) Genes 146. According to Mendel, what kind of genes "disappear" in FI pea plants? a) sex-linked b) dominant c) recessive d) codominant OE compilations OE compilations e) lethal 147. If tall (D) is dominant to dwarf (d), and two homozygous varieties DD and dd are crossed, then what kind of progeny will be produced? a) all intermediate forms b) all tall c) all dwarf d) ½ tall, ½ dwarf e) ¾ tall, ¼ dwarf 148. If two genes are on the same chromosome, a) crossing over occurs frequently. b) they assort independently. c) they are in the same linkage group. d) they are segregated during meiosis. e) an inversion will usually occur. 149. In genetic analyses, researchers know that linkage of genes will introduce exceptions to the principle of dominance. a) segregation. b) recessiveness. c) independent assortment. d) chromosomal inheritance. 150. If two genes are almost always found in the same gamete, a) they are located close together on the same chromosome. b) they are located on nonhomologous chromosomes. c) they are located far apart on the same chromosome. d) they are found on the sex chromosome. e) all except c 151. Which of the following statements is correct? a) The ability to map the position of genes on a chromosome depends on the frequency of crossing over. b) The map distances between genes on a chromosome map mark only relative distances between them, depending on crossover frequency. c) The chance of a crossover only partially depends upon the distance between genes. d) The map distance in a chromosome map refers to actual physical distance between genes. e) both a and b 152. Which of the following would be the least satisfactory organism for genetic research? a) humans b) bacteria c) corn d) fruit flies OE compilations OE compilations e) peas 153. In a pedigree chart, a male showing the specific trait being studied is indicated by a a) darkened square. b) clear square. c) darkened diamond. d) clear triangle. e) darkened circle. 154. In karyotyping, individual chromosomes may be distinguished from others by a) a comparison of chromosome lengths. b) bands produced on chromosomes by differential staining. c) the position of centromeres. d) all of the above e) none of the above 155. In a pedigree chart, a female who does not demonstrate the trait being studied is represented by a a) darkened square. b) clear diamond. c) clear circle. d) darkened triangle. e) darkened oval. 156. Each of the following would be classified as a genetic disorder except ____, which is an abnormality. a) albinism b) webbed toes c) hemophilia d) Down syndrome e) XYY 157. An autosomal recessive disorder a) requires that only one parent be a carrier. b) displays its symptoms only in heterozygotes. c) is more frequent in males than females. d) will appear only in children of parents who both carry the gene. e) is dominant in females. 158. Pairs of identical units formed by chromosome duplication are called ___, and are held together by ______ a) daughter chromosomes, hydrogen bonding b) daughter chromatids, spindle fibers c) sister chromosomes, histone proteins d) sister chromatids, centromeres OE compilations OE compilations e) Both a and b are true. 159. The probability of producing a normal child by two parents who are carriers for an autosomal recessive disorder is a) 50 percent. b) 0 percent. c) 100 percent. d) 25 percent. e) 75 percent. 160. Galactosemia a) is an X-linked recessive trait expressed more commonly in males. b) occurs more frequently in some ethnic groups than others. c) is an autosomal recessive inheritance. d) must be homozygous to be expressed. e) both c and d 161. Like many genetic disorders, galactosemia is a disruption of a metabolic pathway due to a malfunctioning a) reactant. b) cofactor. c) enzyme. d) energy source. e) product. 162. Which of the following diseases could be eliminated in one generation if everyone that develops or will develop the disease could be sterilized or persuaded not to have children? a) hemophilia b) albinism c) sickle-cell anemia d) galactosemia e) Huntington's disorder 163. _____ refers to multiple independent pairs of genes having similar and additive effects on the same characteristic. a) Codominance b) Epistasis c) Polygenic inheritance d) Complete dominance e) Additive dominance 164. The work with sickle-cell anemia resulted in a) an understanding of all metabolic disorders. b) a cure for sickle-cell anemia. OE compilations OE compilations c) a change of the one gene, one enzyme hypothesis to one gene, one polypeptide hypothesis. d) the foundation for blood typing and transfusion. e) both a and b 165. Research on nutrient requirements in bread mold led to the idea that one gene specifies the makeup of one a) amino acid. b) enzyme. c) polypeptide. d) both b and c are correct e) a, b, and c are correct 166. A chromosome's gene sequence that was ABCDEFG before modification and ABCDLMNOP afterward is an example of a) inversion. b) deletion. c) duplication. d) translocation. e) aneuploidy. 167. A chromosome's gene sequence that was ABCDEFG before modification and ABCDCDEFG afterward is an example of a) inversion. b) deletion. c) duplication. d) translocation. e) aneuploidy. 168. A chromosome that has been broken and rejoined in a reversal sequence has undergone a) inversion. b) deletion. c) duplication. d) translocation. e) aneuploidy. 169. Chromosomal aberrations can be produced by exposure to a) viruses. b) radiation. c) various chemicals. d) a and b only e) a, b, and c 170. A chromosome's gene sequence that was ABCDEFG before damage and ABCFG after is an example of OE compilations OE compilations a) inversion. b) deletion. c) duplication. d) translocation. e) aneuploidy. 171. A chromosome's gene sequence that was ABCDEFG before damage and ABFEDCG after is an example of a) inversion. b) deletion. c) duplication. d) translocation. e) aneuploidy. 172. Certain human cancer cells may demonstrate which of the following? a) Deletion b) Inversion c) Translocation d) Duplication e) none of the above 173. Which of the following is a transfer of genes between non-homologous chromosomes? a) crossing over b) aneuploidy c) trisomy d) translocation e) duplication 174. Polyploidy is more common in plants than animals because a) diploid gametes are more common in plants. b) sterile plants can reproduce asexually. c) plants generally do not have sex chromosomes. d) plants can self-fertilize. e) all of the above 175. Queen Victoria a. was a carrier of hemophilia. b. had a hemophilic parent. c. had hemophilia. d. married a man with hemophilia. e. both b and d 176. In cocker spaniels, black coat color (B) is dominant over red (b), and solid color (S) is dominant over spotted (s). If a red male was crossed with a black female to produce a red spotted puppy, the genotypes OE compilations OE compilations a) Bb Ss x Bb Ss b) bb Ss x Bb Ss. c) bb ss x Bb Ss. d) bb Ss x Bb ss. e) Bb ss x Bb ss. 177. Genes are a) located on chromosomes. b) inherited in the same way as chromosomes. c) arranged in linear sequence on chromosomes. d) assorted independently during meiosis. e) all of the above 178. Chromosomes other than those involved in sex determination are known as a) nucleosomes. b) heterosomes. c) alleles. d) autosomes. e) liposomes. 179. Sex chromosomes a) determine gender. b) vary from one sex to another. c) carry some genes that have nothing to do with sex. d) were unknown to Mendel. e) all of the above 180. DNA coding regions that affect the same trait are called a) homologues. b) alleles. c) autosomes. d) loci. e) gametes. 181. The location of a gene on a chromosome is its a) centromere. b) locus. c) autosome. d) allele. e) none of the above 182. A karyotype a) compares one set of chromosomes to another. b) is a visual display of chromosomes arranged according to size. c) is a photograph of cells undergoing mitosis during anaphase. d) of a normal human cell shows forty-eight chromosomes. OE compilations OE compilations e) cannot be used to identify individual chromosomes beyond the fact that two chromosomes are homologues. 183. How have the difficulties associated with studies of human genetics in part been overcome? a) By selective mating within some communities. b) By applying the laws of probability to data obtained from a large sample of individuals. c) By applying artificial selection to some human genetic traits. d) Both a and b are true. e) Both a and c are true. 184. Karyotyping is usually done using what kind of cells? a) muscle b) blood c) cartilage d) sex e) epidermal 185. Which chemical is used to keep chromosomes from separating during metaphase? a) Giemsa stain b) acetone c) colchicine d) alcohol e) formaldehyde 186. Colchicine interferes with the function of a) microtubules. b) ribosomes. c) centrioles. d) centromeres. e) chromosomes. 187. Karyotype analysis a) is a means of detecting and reducing mutagenic agents. b) is a surgical technique that separates chromosomes that have failed to segregate properly during meiosis II. c) is used in prenatal diagnosis to detect chromosomal mutations and metabolic disorders in embryos. d) substitutes defective alleles with normal ones. e) all of the above 188. Karyotyping involves taking pictures of chromosomes during a) prophase. b) telophase. OE compilations OE compilations c) metaphase. d) interphase. e) anaphase. 189. With respect to chromosomes, the difference between normal human males and females is defined by which of the following? a) In females one X is deleted. b) Females possess one X and one Y. c) In males an X is replaced by a Y. d) Females have three X's. e) Males have two X's and a Y. 190. Which of the following statements is false? a) The SRY gene is absent in all females. b) The SRY gene apparently is the gene that controls the development of male sexuality. c) The development of maleness is by default because males lack two X chromosomes. d) Maleness develops in the embryo before femaleness. e) There is no difference in external genitalia of males or females until four weeks after conception when the genes determining sex begin to be expressed. 191. Concerning the sex chromosomes, which of the following is correct? a) The Y chromosome carries a greater number of nonsexual traits. b) X and Y are different in size but carry nearly equal numbers of genes. c) The X chromosome carries more genes for nonsexual traits. d) The X chromosome carries only gender-related genes. e) The X chromosome carries the TDF gene. 192. Who was the first to use fruit flies in genetics experiments? a) Morgan b) Mendel c) Sturtevant d) Weismann e) Flemming 193. In his experiments with Drosophila melanogaster, Morgan demonstrated that a) fertilized eggs have two sets of chromosomes, but eggs and sperm have only one set in each gamete. b) aneuploidy exists in karyotypes that have undergone deletions and inversions in specific chromosomes. c) colchicine is effective in producing polyploidy in F2 generations. d) certain genes are located only on an X chromosome and have no corresponding alleles on the Y chromosome. e) all of the above 194. An X-linked carrier is a a) homozygous dominant female. OE compilations OE compilations b) heterozygous female. c) homozygous recessive female. d) homozygous male. e) heterozygous male. 195. A human X-linked gene is a a) found only in males. b) more frequently expressed in females. c) found on the Y chromosome. d) transmitted from father to son. e) found on the X chromosome. 196. Gene mapping a) applies only to genes located on the same chromosomes. b) represents actual physical distance between genes. c) is based upon the frequency of crossing over. d) can be accomplished only by using the sex chromosomes. e) Two of the above choices are correct. 197. Which of the following statements is false? a) Crossing over tends to reduce the frequency that two linked genes are inherited together. b) Independent assortment of homologous chromosomes during meiosis increases variation. c) Crossing over leads to variation. d) Abnormal number or structure of chromosomes may influence the course of evolution. e) The closer together genes are found on a chromosome the greater is the chance that crossing over will occur between them. 198. All of the genes located on a given chromosome constitute a) karyotype. b) bridging cross. c) wild-type allele. d) linkage group. e) none of the above. 199. The incidence of cancer increases dramatically with age because a) the Ras protein is more likely to be hyperactive after age sixty. b) proteasomes become more active with age. c) as we age, normal cell division inhibitors cease to function. d) the longer we live, the more mutations accumulate. e) tumor-suppressor genes are no longer able to repair damaged DNA. 200. Which of these is not a carcinogen? a) testosterone b) cigarette smoke c) UV light d) fat OE compilations OE compilations e) all of the above are carcinogens SECTION II 1. a) b) c) d) e) 2. a) b) c) d) e) 3. a) b) c) d) e) 4. a) b) c) d) e) 5. a) Symptoms of phenylketonuria (PKU) may be minimized or suppressed by a diet low in serine. glycine. phenylalanine. proline. glutamic acid. Sickle-cell anemics should avoid phenylalanine. strenous activity. high oxygen conditions. sunlight. diet colas. Amniocentesis involves sampling the fetus directly. the fetal cells floating in the amniotic fluid. sperm. blood cells. placental cells. Amniocentesis is a surgical means of repairing deformities. a form of chemotherapy that modifies or inhibits gene expression or the function of gene products. used in prenatal diagnosis to detect chromosomal mutations and metabolic disorders in embryos. a form of gene replacement therapy. all of the above In prenatal diagnosis, the newest procedure that can be performed early in pregnancy involves sampling the amnion. OE compilations OE compilations b) c) d) e) 6. allantois. chorion. yolk sac. umbilical cord. The most recent technique for analyzing the genetics of the unborn child involves the sampling of a) the fetus directly. b) cells in the amniotic fluid. c) material from the allantois. d) the chorionic villi. e) yolk sac material. 7. Four of the five answers listed below describe sets of chromosomes with extra numbers. Select the exception. a) polyploid b) tetraploid c) diploid d) triploid e) allopolyploid 8. Four of the five answers listed below are organisms widely used in genetic research. Select the exception. a) peas b) fruit flies c) Neurospora d) dogfish shark e) E. coli 9. Which of the following is the most precise hypothesis about gene action? a) One gene controls one enzyme. b) Human metabolic defects may arise from absent or defective enzymes in a metabolic pathway. c) One gene controls one polypeptide. d) Genes code for proteins in general, not just enzymes. e) One gene codes for the amino acid sequence of one polypeptide chain. 10. DNA from bacteria differs from DNA in humans in which of the following ways? a) base composition b) sugar-phosphate linkage c) nucleotide sequence d) bonding of the helix e) all of the above 11. A linear stretch of DNA that specifies the sequence of amino acids in a polypeptide is called a(n) OE compilations OE compilations a) codon. b) intron. c) messenger. d) gene. e) enzyme. 12. The DNA molecule usually is made up of how many strands? a) 1 b) 2 c) 3 d) 6 e) 12 13. Molecules carry protein-assembly instructions from the nucleus to the cytoplasm. a) Template DNA b) Messenger RNA c) Transfer RNA d) Ribosomal RNA e) all of the above 14. The RNA molecule is made up of how many strands? a) 1 b) 2 c) 3 d) 6 e) 12 15. The "central dogma" of molecular biology a) explains the structural complexity of genes. b) describes the flow of information. c) is based upon the role of proteins in controlling life. d) does not explain how genes function. e) explains evolution in terms of molecular biology. 16. The changing of a business letter from shorthand to typewritten copy is analogous to a) translation of mRNA. b) transcription of DNA. c) protein synthesis. d) deciphering the genetic code. e) replication of DNA. 17. All the different kinds of RNA are transcribed in the a) mitochondria. b) cytoplasm. c) ribosomes. d) nucleus. OE compilations OE compilations e) endoplasmic reticulum. 18. The form of RNA that carries the code from the DNA to the site where the protein is assembled is called a) messenger RNA. b) nuclear RNA. c) ribosomal RNA. d) transfer RNA. e) structural RNA. 19. The nitrogenous base found in DNA but not in RNA is a) adenine. . b) cytosine. c) guanine. d) uracil. e) thymine. 20. DNA and RNA are alike in a) the pentose sugar. b) all the nitrogenous bases used to assemble the genetic code. c) the number of strands. d) their function in genetics. e) none of the above 21. Which substance is found in RNA but not in DNA? a) thymine b) deoxyribose c) uracil d) guanine e) cytosine 22. The nitrogenous base found in RNA but not in DNA is a) adenine. b) cytosine. c) guanine. d) uracil. e) thymine. 23. Transfer RNA differs from other types of RNA because it a) transfers genetic instructions from cell nucleus to cytoplasm. b) specifies the amino acid sequence of a particular protein. c) carries an amino acid at one end. d) contains codons. e) none of the above 24. The wobble effect pertains to the matching of a) codons with anticodons. OE compilations OE compilations b) codons with exons. c) exons with introns. d) template DNA with messenger RNA. e) messenger RNA with ribosomal RNA. 25. Eukaryotic ribosomes function as a) a single unit. b) two-part units. c) three-part units. d) four-part units. e) a multidivisional unit. 26. All mRNA transcripts begin with a) methionine. b) a ribosome. c) AUG. d) the P site. e) an anticodon. 27. Which of the following statements is false? a) In chain elongation, the amino acids are added to the chain according to the sequence in the messenger RNA. b) The messenger RNA molecule is stationary and series of ribosomes called polysomes travel along the molecule manufacturing series of polypeptides at the same time. c) The shape of transfer RNA molecules is uniform and is maintained by hydrogen bonds. d) Enzymes found in the ribosome catalyze the formation of the bonds in the new polypeptide. e) None of the above statements is false. 28. The maximum number of tRNAs that can be on one ribosome at one time is a) 2. b) 3. c) 43 d) unlimited. e) unknown. 29. A polysome is a) one of the units of a ribosome. b) the nuclear organelle that synthesizes RNA. c) an organelle that functions similarly to a ribosome during meiosis. d) the two units of a ribosome considered together. e) an mRNA molecule with several ribosomes attached. 30. A gene mutation a) is a change in the nucleotide sequence of DNA. b) may be caused by environmental agents. OE compilations OE compilations c) may arise spontaneously. d) can occur in any organism. e) all of the above 31. Which of the following statements is true? a) Gene mutations occur independently of each other. b) Gene mutations are relatively rare. c) The reason that two antibiotics may be given at one time is due to the very remote possibility that two gene mutations could occur in the same cell at the same time. d) Mutations are random; that is, it is impossible to predict exactly when a specific gene will mutate but an expected frequency can be assigned. e) all of the above 32. Which event may occur in all viruses, prokaryotes, and eukaryotes? a) duplication b) aneuploidy c) translocation d) mutation e) all of the above 33. Mutations can be a) random. b) beneficial. c) lethal. d) heritable. e) all of the above 34. Frameshift mutations may involve a) substitution of nucleotides. b) substitution of codons. c) substitution of amino acids. d) addition or deletion of one to several base pairs. e) all of the above 35. Sickle-cell anemia has been traced to what type of mutation? a) frameshift b) transposable element c) mutagenic d) base-pair substitution e) viral 36. The difference between normal and sickle-cell hemoglobin is based upon a) the number of amino acids in the molecule. b) the substitution of one amino acid for another. c) the number and orientation of the amino acid chains attached to the heme portion of the molecule. OE compilations OE compilations d) the number of oxygen molecules that can be carried. e) the type of bone marrow that produces it. 37. In a mutation, a) the new codon may specify a different amino acid but may not change the function of the new protein produced. b) the new codon may specify the same amino acid as the old codon. c) the new codon and resulting amino acid may destroy the function of the protein specified. d) All of the above may be true. 38. Polyploidy a) can occur naturally. b) occurs when there are more than two sets of chromosomes. c) can be artificially induced by colchicine. d) is responsible for some of our major foods. e) all of the above 39. Triploids a) are usually sterile. b) are produced by the fusion of a diploid and a haploid. c) cannot undergo meiosis. d) are polyploids. e) all of the above 40. Which of the following does NOT belong with the other four? a) inversion b) polyploidy c) deletion d) duplication e) translocation 41. The condition occurring when an organism has a 2n + 1 chromosome composition is known as a) monosomy. b) trisomy. c) diploid. d) aneuploidy. e) both b and d 42. If a gamete is missing one chromosome, a) the chromosome number is expressed as 2n -1. b) then one chromosome is without its homologue. c) the condition is called monosomy. d) only a and c e) a, b, and c 43. If nondisjunction occurs during meiosis, OE compilations OE compilations a) the resulting sex cells will be heterogametes. b) one-half of the resulting cells will exhibit trisomy and the other half monosomy. c) diploid cells will be produced. d) all gametes would lack a chromosome and these gametes would be infertile. 44. The failure of chromosomes to separate during mitosis or meiosis is called a) genetic displacement. b) trisomy. c) crossing over. d) nondisjunction. e) disjunction. 45. Which of the following is different from the other four? a) nondisjunction b) duplication c) inversion d) deletion e) translocation 46. Down syndrome involves trisomy a) 3. b) 5. c) 15. d) 19. e) 21. 47. In Down syndrome, a) as the age of the mother increases, the chance of the defect occurring in the unborn children increases. b) the father seems to have very little influence on the defect. c) most embryos abort before complete term. d) a person with the defect cannot have a normal child. e) none of the above 48. Syndrome means a) a chromosome disorder. b) a simple genetic disease. c) a set of symptoms that occur together. d) an incurable disease. e) a rare inborn defect. 49. Which of the following designates a normal human female? a) XXY b) XY c) XX d) XYY OE compilations OE compilations e) XO 50. Which of the following conditions is characterized by a karyotype with forty-five chromosomes? a) Turner syndrome b) Down syndrome c) testicular feminization syndrome d) Klinefelter syndrome e) cri-du-chat 51. Suppose that a hemophilic male (X-linked recessive allele) and a female carrier for the hemophilic trait have a non-hemophilic daughter with Turner syndrome. Non-disjunction could have occurred in a) both parents. b) neither parent. c) the father only. d) the mother only. e) none of the above 52. The sex chromosome composition of a person with Turner syndrome is a) XXX. b) XO. c) XXY. d) XYY. e) none of the above 53. Nondisjunction involving the X chromosomes may occur during oogenesis and produce two kinds of eggs. If normal sperm fertilize these two types, which of the following pairs of genotypes are possible? a) XX and XY b) XXY and XO c) XYY and XO d) XYY and YO e) none of the above 54. Which of the following designates a normal human male? a) YY b) XX c) XY d) XO e) XYY 55. The sex chromosome composition of a person with Klinefelter syndrome is a) XXX. b) XO. c) XXY. OE compilations OE compilations d) XYY. e) none of the above. 56. A genetic abnormality that may result in sterile males with mental retardation or breast enlargement is a) XXY. b) XYY. c) Turner syndrome. d) Down syndrome. e) none of the above 57. Males that tend to be taller than average and show mild mental retardation may be designated a) XXY. , b) XYY. c) Turner syndrome. d) Down syndrome. e) none of the above 58. If a study of several pedigrees demonstrated that two parents express a characteristic and none of their children express it, then the trait is controlled by a) a codominant gene. b) a simple dominant gene. c) a recessive gene. d) a sex-linked gene. e) No conclusion can be drawn. 59. If a study of several pedigrees demonstrated that two parents are normal but their children express a trait, then the trait is controlled by a a) codominant gene. b) simple dominant gene. c) recessive gene. d) sex-linked gene. e) No conclusion can be drawn. 60. Aneuploidy would describe all of the following except a) Turner syndrome. b) Klinefelter syndrome. c) translocation. d) XYY e) Down syndrome. 61. Which of the following is NOT true? a) Down syndrome is an example of aneuploidy. b) Human polyploids are lethal. c) Most euploidy embryos miscarry. OE compilations OE compilations d) The rate of aneuploidy is higher in humans than in other mammals. e) On the average, one out of two newly fertilized eggs is an aneuploid. 62. Which is NOT a chromosomal abnormality? a) Deletion b) extra chromosomes c) translocation (exchange of parts between nonhomologues) d) crossing over e) inversion 63. Treatments for genetic disorders currently involve a) substituting normal for defective parents. b) substituting normal for defective genes. c) supplying a missing gene. d) supplying missing enzymes or gene products. e) all of the above 64. Phenotypic treatments for genetic disorders include a) preventing the disorders in the carriers. b) eliminating the defective gene. c) preventing a disorder from being passed on. d) preventing a disorder from being expressed e) all of the above 65. Phenotypic treatments a) may increase the number of defective genes in a population. b) do not affect the number of defective genes in a population. c) decrease the number of defective genes in a population. d) are the ultimate cures for genetic disorders. e) have no biological value for either the individual or the population. 66. PKU can be detected by a) karyotyping. b) urine analysis. c) blood tests. d) saliva tests. e) both band c 67. Gene replacement therapy a) has not yet been used successfully with mammals. b) is a surgical technique that separates chromosomes that have failed to segregate properly during meiosis II. c) has been used successfully to treat victims of Huntington's disorder by removing the dominant damaging autosomal allele and replacing it with a harmless one. d) substitutes defective alleles with normal ones. all of the above OE compilations OE compilations 68. Three of the four answers listed below are different forms of a class of nucleic acids. Select the exception. a) template b) ribosomal c) messenger d) transfer 69. Three of the four answers listed below are involved in gene action. Select the exception. a) replication b) transcription c) translation d) polymerization 70. Four of the five answers listed below are steps in the process of transcription. Select the exception. a) cap put on one end b) introns snipped out c) action by DNA polymerase d) poly-A tail placed on one end e) exons spliced together 71. Four of the five answers listed below are related pairings. Select the exception. a) double-stranded DNA - messenger RNA b) purine - pyrimidine c) codon - anticodon d) small subunit -large subunit e) promoter - terminator 72. Four of the five answers listed below describe changes at the chromosomal level. Select the exception. a) base substitution b) duplication c) translocation d) deletion e) inversion 73. Four of the five answers listed below are chromosomal abnormalities. Select the exception. a) translocation b) elongation c) duplication d) deletion e) inversion 74. Four of the five answers listed below are sources of genetic variation. Select the exception. OE compilations OE compilations a) crossing over b) mutation c) asexual reproduction d) chromosome aberration e) sexual reproduction 75. Four of the five answers listed below are components of a nucleotide. Select the exception. a) pentose sugar b) amino acid c) pyrimidine d) phosphate group e) purine 76. Four of the five answers listed below are related by a common number. Select the exception. a) number of nucleotides in a codon b) number of building blocks (parts) in a nucleotide c) number of stop codons d) number of types of DNA e) number of types of RNA 77. Four of the five answers listed below are conditions caused by chromosomal nondisjunction. Select the exception. a) Down syndrome b) Huntington's disorder c) Turner syndrome d) Klinefelter syndrome e) trisomy 21 78. Four of the five answers listed below are therapeutic measures applied to affected individuals. Select the exception. a) prenatal diagnosis b) chemotherapy c) surgical correction d) diet modification e) environmental adjustment 79. Four of the five answers listed below are methods used to reduce the number of defective genes in a population. Select the exception. a) genetic counseling b) gene replacement c) mutagen reduction d) diet modification e) genetic screening OE compilations OE compilations 80. Four of the five answers listed below are caused by recessive genes. Select the exception. a) Huntington's disorder b) phenylketonuria c) color blindness d) hemophilia e) albinism 81. Friedrich Miescher is credited with a) proposing DNA as the hereditary material. b) finding a cure for pneumonia. c) telling us that A = T and G = C. d) discovering nucleic acids. e) only a and d are correct 82. When Fred Griffith injected mice with a mixture of dead, pathogenic, encapsulated S cells and living unencapsulated R cells of Streptococcus pneumoniae, he discovered that a) the previously harmless strain (S) had inherited the ability to kill mice. b) the dead mice teemed with living pathogenic (R) cells. c) the killer strain (R) was encased in a protective capsule. d) b and c above e) all of the above 83. Fred Griffith's experiments a) produced a vaccine against bacterial pneumonia. b) demonstrated that rough (R) bacteria cause pneumonia. c) provided evidence that genetic material from one bacterial culture could be transferred to another culture. d) showed that rough bacteria injected into mice will be changed by the mice to smooth (S) bacteria. e) converted harmless smooth bacteria into lethal rough bacteria. 84. The significance of Fred Griffith's experiment in which he used two strains of Streptococcus pneumoniae is that a) the semiconservative nature of DNA replication was finally demonstrated. b) it demonstrated that harmless cells had become permanently transformed through a change in the bacterial hereditary system. c) it established that pure DNA extracted from disease- causing bacteria transformed harmless strains into killer strains. d) it demonstrated that radioactively labeled bacteriophages transfer their DNA but not their protein coats to their host bacteria. e) all of the above 85. Which of the following statements is NOT true about Fred Griffith's experiments? a) Mice injected with smooth (S) bacteria die. b) Mice injected with heat-killed smooth bacteria die. OE compilations OE compilations c) Mice injected with heat-killed smooth bacteria and live rough (R) bacteria die. d) Mice injected with rough bacteria live. e) Smooth bacteria are transformed into harmless rough bacteria. 86. Which scientist(s) identified the transforming substance involved in changing rough (R) bacteria to smooth (S)? a) Avery b) Griffith c) Chargaff d) Hershey and Chase e) Pauling 87. Bacteriophages are a) large bacteria. b) pathogens (disease-producing bacteria). c) viruses. d) cellular components. e) protistans. 88. The significance of the experiments in which 32P and 35S were used is that a) the semiconservative nature of DNA replication was finally demonstrated. b) it demonstrated that harmless bacterial cells had become permanently transformed through a change in the bacterial hereditary system. c) it established that pure DNA extracted from disease-causing bacteria transformed harmless strains into killer strains. d) it demonstrated that radioactively labeled bacteriophages transfer their DNA but not their protein coats to their host bacteria. e) none of the above 89. In the cycle of viral infection, which of the following is the last process to occur? a) invasion of viruses into the body b) replication of viral particles by bacteria c) lysis of the bacteria d) attachment of virus to bacteria e) injection of nucleic acid into the bacteria 90. If a mixture of viruses labeled with radioactive sulfur and phosphorus is placed in a bacterial culture, a) the bacteria will absorb radioactive sulfur. b) the bacteria will absorb radioactive phosphorus. c) the bacteria will absorb both radioactive sulfur and phosphorus. d) the bacteria will not absorb either sulfur or phosphorus. e) the viruses will not attach to the bacteria. 91. Nucleic acid contains a) sulfur. OE compilations OE compilations b) c) d) e) phosphorus. potassium. iron. manganese. 92. Which of the following statements is false? a) Protein molecules contain no phosphorus. b) Hershey and Chase discovered that 35S and not 32P had been incorporated into the hereditary system of the bacteria. c) Bacteriophages are viruses that inject their nucleic acid genetic code into bacteria and use the bacterial genetic apparatus to make viral proteins. d) Each nucleotide is composed of a five-carbon sugar, a phosphate group, and either a purine or pyrimidine. e) Viruses are particles of nucleic acid encased in protein. 93. The experiments of which of the following researchers clearly distinguished DNA as the hereditary material (as opposed to protein)? a) Pauling b) Hershey and Chase c) Griffith d) Watson and Crick e) Avery 94. Sulfur is a) found in proteins, but not nucleic acids. b) a vital component of DNA. c) found in nucleic acids but not proteins. d) needed for bacteriophages to attach to bacteria. e) needed for the enzyme that splits the wall of bacteria. 95. The building blocks of nucleic acids are a) amino acids. b) nucleotides. c) pentose sugars. d) phosphate groups. e) nitrogenous bases. 96. Which of the following terms is NOT related to the other four? a) amino acids b) nucleotides c) pentose sugars d) phosphate groups e) nitrogenous bases 97. A nucleotide may contain a) a purine. OE compilations OE compilations b) c) d) e) a pentose. a phosphate group. a pyrimidine. all of the above 98. Which scientist(s) discovered the basis for the base-pair rule, which states that the amounts of adenine and thymine match, as do the amounts of cytosine and guanine? a) Avery b) Griffith c) Chargaff d) Hershey and Chase e) Pauling 99. DNA varies from species to species in its a) base-pair bonding. b) relative amounts of nucleotide bases. c) sequence of base pairs. d) a and c only e) b and c only 100. Mendel's single factor crosses led to which of the following rules of inheritance? a) concept of dominance b) law of segregation c) support for the particulate theory of inheritance d) all of the above 101. In a Chi square test of a genetic cross there are n different phenotypic classes in the offspring. What is the value for the degrees of freedom for the test? . a) n b) n-l c) n + 1 d) 2n e) none of the above 102. The pea plant, Pisum sativum, was used by Mendel as a model organism for which of the following reason(s): a) there were easily visible traits such as flower color and seed shape. b) self-fertilization was possible. c) it was relatively easy to grow. d) all of the above are correct. 103. The observable characteristic of an organism is called its ___ a) genotype b) phenotype c) pedigree d) allele OE compilations OE compilations e) none of the above 104. If an organism contains two identical alleles for the same trait, it is said to be which of the following? a) cross-fertilized b) heterozygous c) homozygous d) a hybrid e) none of the above 105. Two individuals who are heterozygous for a given trait are crossed. What will be the phenotypic ratio of their offspring? a) 75% will display the dominant trait, 25% will display the recessive trait b) 100 % will display the recessive trait c) 100% will be heterozygous individuals d) 50% will display the dominant trait, 50% will display the recessive trait e) all of the above are possible 106. In a two-factor cross, if two individuals who are heterozygous for both traits are crossed with one another, what will be the phenotypic ratio of their offspring based on Mendel's work? a) 3:1 b) 1:2:1 c) 9:3:3: 1 d) 15:1 e) 9:6:1 107. The Punnett square is best used for which of the following? a) to predict the goodness of fit of observations to expectations b) to conduct crosses of four or more traits c) for pedigree analysis d) to visualize the possible outcomes of one and two-factor Mendelian crosses 108. Which of the following is correct concerning a pedigree analysis? a) it is useful when examining organisms that produce a small number of offspring b) it is useful when ethical problems prohibit controlled matings c) it is frequently used to study patterns of inheritance in humans d) it can be used to determine if a trait is dominant or recessive e) all of the above are correct *For questions 109 to 113, match the events of MEIOSIS prophase I to it correct function. 109. 110. 111. 112. 113. Diakinesis Zygotena Diplotena Leptotena Pachytena OE compilations OE compilations a) b) c) d) e) Homologous chromosomes recognize each other by synapsis. The chromosomes begin to condense, and are now visible using a microscope. The stage in which crossing over occurs. The synaptonemal complex disappears. The final stage of prophase 1. 114. A testcross is always conducted between an individual whose genotype is unknown, and which of the following? a) a heterozygous individual b) a homozygous dominant individual c) a homozygous recessive individual d) any of the above will work 115. A reciprocal cross is used to determine which of the following? a) if a trait is autosomal or sex-linked b) the number of autosomal chromosomes c) the dominance / recessive nature of a trait d) the sex of the organism e) none of the above 116. Thoman Hunt Morgan's experiment with white-eyed Drosophila provided proof of which of the following? a) law of independent assortment b) chromosomal theory of inheritance c) theory of natural selection d) law of segregation e) none of the above 117. An organism has 20 pairs of chromosomes at the start of mitosis, how many chromosome pairs with each cell have at the end of mitosis? a) 5 b) l0 c) 20 d) 40 118. During which of the following stages of the cell cycle is the DNA of the organism replicated? a) prophase b) anaphase c) S phase d) G2 phase 119. Before the start of meiosis, on which of the following would the genetic material be almost identical? a) homologous chromosomes OE compilations OE compilations b) sister chromatids c) non-sister chromatids of homologous chromosomes d) none of the above 120. During which of the following stages of meiosis does synapsis and crossing over occur? a) metaphase b) cytokinesis c) prophase I d) telophase II e) prophase II 121. The Sry gene of humans displays which of the following patterns of inheritance? a) X- linked b) pseudoautosomal c) autosomal d) Y-linked 122. A trait that has a different level of expression in males than females is an example of which of the following? a) sex-influenced inheritance b) sex-limited inheritance c) gene dosage d) all of the above e) none of the above 123. Expressivity is most often associated with which of the following? a) multiple allele systems b) heterozygote advantage c) incomplete penetrance d) incomplete dominance e) none of the above 124. Coat color in rabbits and human blood groups are both examples of __ . a) multiple allele systems b) epistatic interactions c) gene dosage d) simple Mendelian inheritance e) all of the above 125. The most common allele in the population is called the ___ a) mutant allele b) essential allele c) dominant allele d) wild-type allele e) recessive allele OE compilations OE compilations 126. Phenotypic blending is the result of ____ a) incomplete dominance b) incomplete penetrance c) codominance d) overdominance 127. A heterozygote that has a selective advantage over the homozygous dominant individual is an example of ____ a) gene interaction b) codominance c) temperature sensitive lethals d) overdominance 128. A trait that is only expressed in one sex of the species is an example of __ . a) temperature-sensitive alleles b) sex-influenced inheritance c) sex-limited inheritance d) X-linked inheritance 129. Pseudodominance is the result of a(n) _____ a) inversion b) translocation c) deletion d) duplication 130. The chromosome number of an individual with non-familial Down's syndrome is indicated as a) 2n - l b) 3n c) 2n+ 1 d) n + 2 131. Prader- Willi and Angelmans syndromes are a result of a(n), ____ a) inversion b) translocation c) deletion d) duplication 132. Liver cells in humans exhibit which of the following? a) alloploidy b) endopolyploidy c) monoploidy d) aneuploidy For questions* 133 to 139, match each statement with the researcher who contributed the information to our understanding of DNA. OE compilations OE compilations a) Avery, MacLeod, and McCarty b) Hershey and Chase c) Griffith d) all of the above 133. Discovered the process of transformation in bacteria. Ans.C 134. Treated Streptococcus pneumoniae extracts with enzymes to further identify the genetic material. Ans.A 135. Used Streptococcus pneumoniae as a model system. 136. Used radioactively labeled phages to determine if DNA or protein was the genetic material. ANS. B 137. Used a bacteriophage (T2) as the model system. Ans B 138. Demonstrated that the transforming principle from the experiments with Streptococcus pneumoniae is DNA. 139. Demonstrated that DNA is the genetic material of bacteriophage T2. Ans. B 140. The backbone of DNA is made up of ____ a) deoxyribose sugar b) purines c) pyrimidines d) phosphate groups e) none of the above 141. ___ used X-ray crystallography data to provide the first evidence of the threedimensional structure of DNA. a) Chargaff b) Watson and Crick c) Franklin d) Griffith 142. In a DNA nucleotide within a DNA strand, this is the component that can vary. a) phosphate groups b) phosphodiester bonds c) sugar d) type of base e) none of the above vary 143. This is the form of DNA most common in living cells. a) A DNA b) B DNA c) triplex DNA d) ZDNA e) K DNA 144. ___ discovered the process of transformation in bacteria. OE compilations OE compilations a) Avery and colleagues b) Griffith c) Chargaff d) Pauling e) Franklin 145. In their experiments with bacteriophage T2, Hershey and Chase labeled the D A using -' a) 15N b) 35S c) 32P d) 3H 146. __ demonstrated that the genetic material in bacteriophage T2 was DNA. a) Watson and Crick b) Avery and colleagues c) Franklin d) Hershey and Chase e) Pauling 147. The 5' to 3' configuration of DNA is called its ____ property. a) complementary b) A T/GC rule c) directionality d) antiparallel 148. These were the first individuals to demonstrate that DNA is a double-helix. a) Watson and Crick b) Pauling c) Franklin d) Chargaff 149. .The structural unit of a DNA strand is the _____ a) nucleoside b) nucleotide c) ribose sugar d) purine e) none of the above 150. From X-ray diffraction data, which of the following was determined about DNA? a) The molecule had uniform diameter. b) The molecule was long and narrow. c) Part of the molecule repeated itself often. d) The shape of the molecule could be spiral. e) all of the above 151. Rosalind Franklin's research contribution was essential in OE compilations OE compilations a) establishing the double-stranded nature of DNA. b) establishing the principle of base pairing. c) establishing most of the principal structural features of DNA. d) sequencing DNA molecules. e) determining the bonding energy of DNA molecules. 152. Rosalind Franklin used which technique to determine many of the physical characteristics of DNA? a) transformation b) transmission electron microscopy c) density-gradient centrifugation d) x-ray diffraction e) all of the above 153. James Watson and Francis Crick a) established the double-stranded nature of DNA. b) confirmed the principle of base pairing. c) explained how DNA's structure permitted it to be replicated. d) proposed the concept of the double helix. e) all of the above 154. In the bonding of nitrogenous bases, a) adenine is paired with cytosine. b) adenine is paired with guanine. c) cytosine is paired with thymine. d) guanine is paired with cytosine. 155. In the bonding of two nucleotides, a) hydrogen bonds are used. b) adenine and thymine bind together. c) purines bind with pyrimidines. d) double-ring nitrogenous bases connect to single-ring bases. e) all of the above 156. The DNA molecule could be compared to a a) hairpin. b) ladder. c) key. d) globular mass. e) flat plate. 157. In DNA, complementary base pairing occurs between a) cytosine and uracil. b) adenine and guanine. c) adenine and uracil. d) adenine and thymine. OE compilations OE compilations e) all of the above 158. Adenine and guanine are a) double-ringed purines. b) single-ringed purines. c) double-ringed pyrimidines. d) single-ringed pyrimidines. e) amino acids. 159. If a purine bonded to a purine in DNA, the molecule would ___ in that region. a) be constricted b) be perfectly normal c) lose a sugar-phosphate unit d) unwind e) bulge 160. In the comparison between a spiral staircase and a DNA molecule, the steps would correspond to a) sugars. b) hydrogen bonds. c) base pairs. d) nucleotides. e) phosphates. 161. In DNA molecules, a) the nucleotides are arranged in a linear, unbranched pattern. b) the nitrogenous bases are found on the outside of the molecule. c) the sugar-phosphate pattern runs the same way on each DNA strand. d) all of the above e) none of the above 162. Which of the following statements is true? a) The hydrogen bonding of cytosine to guanine is an example of complementary base pairing. b) Adenine always pairs up with guanine in DNA, and cytosine always teams up with thymine. c) Each of the four nucleotides in a DNA molecule has the same nitrogen-containing base. d) When adenine base pairs with thymine, they are linked by three hydrogen bonds. e) In the DNA of all species, the amount of purines never equals the amount of pyrimidines. 163. Each DNA strand has a backbone that consists of alternating a) purines and pyrimidines. b) nitrogen-containing bases. c) hydrogen bonds. d) sugar and phosphate molecules. e) amines and purines. 164. Who among the following was NOT involved in working out the structure of DNA? OE compilations OE compilations a) Avery b) Watson c) Wilkins d) Franklin e) Chargaff 165. The ultimate explanation for resemblances of traits from one generation to another is a) gamete formation. b) semiconservative DNA replication. c) sexual reproduction. d) protein synthesis. e) bloodlines. 166. The appropriate adjective to describe DNA replication is a) nondisruptive. b) semiconservative. c) progressive. d) natural. e) lytic. 167. Replication of DNA a) produces RNA molecules. b) produces only new DNA. c) produces two molecules, each of which is half-new and half-old DNA joined lengthwise to each other. d) generates excessive DNA, which eventually causes the nucleus to divide. e) is too complex to characterize. 168. DNA strands serve as which of the following during DNA synthesis? a) replicate b) substitute c) template d) source of nucleotides e) all of the above 169. After three replications of a single DNA molecule, what percent of the resulting double helices contain one strand of the "original" DNA? a) 0 percent b) 25 percent c) 50 percent d) 75 percent e) 100 percent 170. The primary function of DNA ligase is to a) cut the two strands of the DNA molecule prior to replication. b) attach free nucleotides to the growing chain. OE compilations OE compilations c) remove bases that might have been inserted incorrectly. d) seal new short stretches of nucleotides into one continuous strand . e) fragment old DNA that is no longer of use to the cell. 171. DNA polymerase a) is an enzyme. b) adds new nucleotides to a strand. c) proofreads DNA strands to see that they are correct. d) derives energy from A TP for synthesis of DNA strands. e) all of the above 172. Proteins associated with DNA in eukaryotes are called a) repressors. b) tryptophans. c) histones. d) nucleosomes. e) operons. 173. Histone-DNA units are called a) polysomes. b) ribosomes. c) nucleosomes. d) chromocenters. e) vesicles. 174. The DNA molecule is associated with histone to form a) looped domains. b) scattered introns. c) hairpin loops. d) tightly coiled complexes. e) lamp brushes. 175. The difference between normal hemoglobin and sickle-cell hemoglobin is in the a) heme portion of the molecules. b) number of chains of amino acids. c) substitution of a specific amino acid for another specific amino acid. d) substitution of any amino acid for a specific amino acid in the hemoglobin molecule. e) loss of only one amino acid from the normal hemoglobin molecule. 176. Which of the following methods of calculating probability is used if the order of a specific number of events occurring in the total is not important? a) chi square test b) binomial expansion c) product rule d) sum rule OE compilations OE compilations 177. Hydrophobic and ionic interactions between the R groups of amino acids occurs at the __ level of protein structure. a) primary b) secondary c) tertiary d) quaternary 178. The anticodon is located on the --a) ribosome b) mRNA c) tRNA d) rRNA 179. The molecule that attaches the amino acid to the tRNA is called --a) peptidyltransferase b) release factor c) aminoacyl-tRNA transferase d) polysome 180. Simultaneous transcription and translation occurs in ___ organisms. a) prokaryotic b) eukaryotic c) both a and b d) none of the above 181. Translocation of the ribosome occurs during ____ a) elongation b) termination c) initiation d) transcription 182. Which of the following is not a stop codon in most species? a) UAA b) AUG c) UGA d) UAG 183. Which of the following is true regarding the genetic code? a) It is universal. b) It is degenerate. c) It allows wobble in the third base. d) All of the above are correct. 184. The decoding function of translation occurs during ___ a) initiation b) elongation c) translocation OE compilations OE compilations d) cotranslational sorting 185. In which of the following ribosomal site receives the polypeptide chain during the peptidyl transfer reaction? a) A site b) P site c) E site d) K site 186. Which of the following types of mutations changes a normal codon to a stop codon? a) silent mutation b) frameshift mutation c) nonsense mutation d) missense mutation e) none of the above 187. A __ mutation returns a variant to the wild type condition. a) forward b) reverse c) lateral d) vertical e) none of the above 188. A mutation that influences the phenotype only under specific environmental conditions is called a ____ mutation a) conditional b) silent c) transitional d) missense 189. cDNA is made using an enzyme called ____ a) dideoxyribonucleotide b) integrase c) reverse transcriptase d) restriction endonuclease 190. Three of the four answers listed below are steps in translation. Select the exception. a) initiation b) replication c) chain elongation d) termination 191. When cells are not responding to normal controls over growth and division, they form a tissue mass known as a a) metastasis. OE compilations OE compilations b) malignancy. c) tumor. d) carcinogen. e) puff. 192. Unusual growth of cells that do not pose a threat to surrounding tissues are termed a) malignant. b) benign. c) metastatic. d) carcinogenic. e) repressed. 193. The myc gene a) can be translocated from chromosome 8 to chromosome 14. b) can lead to Burkitt's lymphoma. c) does not cause cancer until it is moved. d) both a and b, but not c e) a, b, and c 194. Which of the following statements concerning cancer cells is most accurate? a) Oncogenes are part of the regulatory section of a chromosome. b) Tumor cells have lost their inhibition to stop dividing. c) Oncogenes help control runaway cell division. d) Benign tumors usually spread to other body parts. e) Metastasis is the spread of benign tumors. 195. The nature of development is based upon a) which genes are active in a given cell. b) when the genes function. c) what gene products appear. d) the amount of cellular products generated. e) all of the above 196. Which of the following statements is false? a) All the cells of anyone single individual human have the same genes. b) Only red blood cells have hemoglobin genes. c) Different genes are activated depending on the cell they are in. d) Genetically, liver cells and brain cells differ mostly in function. e) Cells don't express all of their genes all of the time. 197. Genes located in different regions of the body during embryonic development may a) be turned on and off. b) never be turned on. c) be turned on and left on. d) be activated for only a short time in one cell and a long time in another cell. OE compilations OE compilations e) all of the above 198. A mammalian female a) usually has one Barr body. b) is a mosaic for the X-linked traits she inherits. c) uses the paternal X chromosome for a Barr body. d) uses the maternal X chromosome for a Barr body. e) always a and b 199. Lyonization of a cat refers to a) hybridization. b) sterilization. c) mosaic phenotype. d) inactivation of one of the X chromosomes. e) both c and d 200. The mosaic effect in human females can be observed in a) skin color. b) hair color. c) distribution of fat cells. d) distribution of sweat glands. e) all of the above DR. KOFI OWUSU-DAAKU TUESDAY SEPTEMBER 17, 2013 OE compilations OE compilations OE compilations OE compilations Compiled by: OPOKU EMMANUEL OE compilations