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ChAPter 16-17 Test - AP Biology

98 Questions
chAPter 16-17 test - AP biology
Questions and Answers
  • 1. 
    • A. 

      Proteins have a greater variety of three-dimensional forms than does DNA.

    • B. 

      Proteins have two different levels of structural organization; DNA has four.

    • C. 

      Proteins are made of 20 amino acids and DNA is made of four nucleotides.

    • D. 

      Only A and C are correct.

    • E. 

      A, B, and C are correct.

  • 2. 
    In his transformation experiments, Griffith observed that
    • A. 

      Mutant mice were resistant to bacterial infections.

    • B. 

      Mixing a heat-killed pathogenic strain of bacteria with a living nonpathogenic strain can convert some of the living cells into the pathogenic form.

    • C. 

      Mixing a heat-killed nonpathogenic strain of bacteria with a living pathogenic strain makes the pathogenic strain nonpathogenic.

    • D. 

      Infecting mice with nonpathogenic strains of bacteria makes them resistant to pathogenic strains.

    • E. 

      Mice infected with a pathogenic strain of bacteria can spread the infection to other mice.

  • 3. 
    • A. 

      The creation of a strand of DNA from an RNA molecule

    • B. 

      The creation of a strand of RNA from a DNA molecule

    • C. 

      The infection of cells by a phage DNA molecule

    • D. 

      The type of semiconservative replication shown by DNA

    • E. 

      Assimilation of external DNA into a cell

  • 4. 
    Avery and his colleagues purified various chemicals from pathogenic bacteria and showed that ________ was (were) the transforming agent.
    • A. 

      DNA

    • B. 

      Protein

    • C. 

      Lipids

    • D. 

      Carbohydrates

    • E. 

      Phage

  • 5. 
    • A. 

      Tobacco mosaic virus

    • B. 

      The related DNA virus

    • C. 

      A hybrid: tobacco mosaic virus RNA and protein from the DNA virus

    • D. 

      A hybrid: tobacco mosaic virus protein and nucleic acid from the DNA virus

    • E. 

      A virus with a double helix made up of one strand of DNA complementary to a strand of RNA surrounded by viral protein

  • 6. 
    The following scientists made significant contributions to our understanding of the structure and function of DNA. Place the scientists' names in the correct chronological order, starting with the first scientist(s) to make a contribution.     I.    Avery, McCarty, and MacLeod     II.    Griffith     III.    Hershey and Chase     IV.    Meselson and Stahl     V.    Watson and Crick
    • A. 

      V, IV, II, I, III

    • B. 

      II, I, III, V, IV

    • C. 

      I, II, III, V, IV

    • D. 

      I, II, V, IV, III

    • E. 

      II, III, IV, V, I

  • 7. 
    • A. 

      DNA passed from the heat-killed strain to the living strain.

    • B. 

      Protein passed from the heat-killed strain to the living strain.

    • C. 

      The phosphorescence in the living strain is especially bright.

    • D. 

      Descendants of the living cells are also phosphorescent.

    • E. 

      Both DNA and protein passed from the heat-killed strain to the living strain.

  • 8. 
    In trying to determine whether DNA or protein is the genetic material, Hershey and Chase made use of which of the following facts?
    • A. 

      DNA does not contain sulfur, whereas protein does.

    • B. 

      DNA contains phosphorus, but protein does not.

    • C. 

      DNA contains nitrogen, whereas protein does not.

    • D. 

      A and B only

    • E. 

      A, B, and C

  • 9. 
    For a science fair project, two students decided to repeat the  Hershey and Chase experiment, with modifications. They decided to label the nitrogen of the DNA, rather than the phosphate. They reasoned that each nucleotide has only one phosphate and two to five nitrogens. Thus, labeling the nitrogens would provide a stronger signal than labeling the phosphates. Why won't this experiment work?
    • A. 

      There is no radioactive isotope of nitrogen.

    • B. 

      Radioactive nitrogen has a half-life of 100,000 years, and the material would be too dangerous for too long.

    • C. 

      Meselson and Stahl already did this experiment.

    • D. 

      Although there are more nitrogens in a nucleotide, labeled phosphates actually have 16 extra neutrons; therefore, they are more radioactive.

    • E. 

      Amino acids (and thus proteins) also have nitrogen atoms; thus, the radioactivity would not distinguish between DNA and proteins.

  • 10. 
    • A. Alfred Hershey and Martha Chase
    • A.
    • B. Oswald Avery, Maclyn McCarty, and Colin MacLeod
    • B.
    • C. Erwin Chargaff
    • C.
  • 11. 
    When T2 phages infect bacteria and make more viruses in the presence of radioactive sulfur, what is the result?
    • A. 

      The viral DNA will be radioactive.

    • B. 

      The viral proteins will be radioactive.

    • C. 

      The bacterial DNA will be radioactive.

    • D. 

      Both A and B

    • E. 

      Both A and C

  • 12. 
    • A. 

      12

    • B. 

      24

    • C. 

      31

    • D. 

      38

    • E. 

      It cannot be determined from the information provided.

  • 13. 
    Chargaff's analysis of the relative base composition of DNA was significant because he was able to show that
    • A. 

      The relative proportion of each of the four bases differs from species to species.

    • B. 

      The human genome is more complex than that of other species.

    • C. 

      The amount of A is always equivalent to T, and C to G.

    • D. 

      Both A and C

    • E. 

      Both B and C

  • 14. 
    All of the following can be determined directly from X-ray diffraction photographs of crystallized DNA except the
    • A. 

      Diameter of the helix.

    • B. 

      Helical shape of DNA.

    • C. 

      Sequence of nucleotides.

    • D. 

      Spacing of the nitrogenous bases along the helix.

    • E. 

      Number of strands in a helix.

  • 15. 
    The DNA double helix has a uniform diameter because ________, which have two rings, always pair with ________, which have one ring.
    • A. 

      Purines; pyrimidines

    • B. 

      Pyrimidines; purines

    • C. 

      Deoxyribose sugars; ribose sugars

    • D. 

      Ribose sugars; deoxyribose sugars

    • E. 

      Nucleotides; nucleoside triphosphates

  • 16. 
    What kind of chemical bond is found between paired bases of the DNA double helix?
    • A. 

      Hydrogen

    • B. 

      Ionic

    • C. 

      Covalent

    • D. 

      Sulfhydryl

    • E. 

      Phosphate

  • 17. 
    Which of the following statements does not apply to the Watson and Crick model of DNA?
    • A. 

      The two strands of the DNA form a double helix.

    • B. 

      The distance between the strands of the helix is uniform.

    • C. 

      The framework of the helix consists of sugar-phosphate units of the nucleotides.

    • D. 

      The two strands of the helix are held together by covalent bonds.

    • E. 

      The purines form hydrogen bonds with pyrimidines.

  • 18. 
    It became apparent to Watson and Crick after completion of their model that the DNA molecule could carry a vast amount of hereditary information in its
    • A. 

      Sequence of bases.

    • B. 

      Phosphate-sugar backbones.

    • C. 

      Complementary pairing of bases.

    • D. 

      Side groups of nitrogenous bases.

    • E. 

      Different five-carbon sugars.

  • 19. 
    • A. 

      A = C

    • B. 

      A = G and C = T

    • C. 

      A + C = G + T

    • D. 

      G + A = T + C

    • E. 

      Both C and D

  • 20. 
    • A. 

      The prokaryotic chromosome is circular, whereas eukaryotic chromosomes are linear.

    • B. 

      Prokaryotic chromosomes have a single origin of replication, whereas eukaryotic chromosomes have many.

    • C. 

      The rate of elongation during DNA replication is higher in prokaryotes than in eukaryotes

    • D. 

      Prokaryotes produce Okazaki fragments during DNA replication, but eukaryotes do not.

    • E. 

      Eukaryotes have telomeres, and prokaryotes do not.

  • 21. 
    The strands that make up DNA are antiparallel. This means that
    • A. 

      The twisting nature of DNA creates nonparallel strands.

    • B. 

      The 5' to 3' direction of one strand runs counter to the 5' to 3' direction of the other strand.

    • C. 

      Base pairings create unequal spacing between the two DNA strands.

    • D. 

      One strand is positively charged and the other is negatively charged.

    • E. 

      One strand contains only purines and the other contains only pyrimidines.

  • 22. 
    Suppose one were provided with an actively dividing culture of E. coli bacteria to which radioactive thymine had been added. What would happen if a cell replicated once in the presence of this radioactive base?
    • A. 

      One of the daughter cells, but not the other, would have radioactive DNA.

    • B. 

      Neither of the two daughter cells would be radioactive.

    • C. 

      All four bases of the DNA would be radioactive.

    • D. 

      Radioactive thymine would pair with nonradioactive guanine.

    • E. 

      DNA in both daughter cells would be radioactive.

  • 23. 
    In the late 1950s, Meselson and Stahl grew bacteria in a medium containing "heavy" nitrogen  (15N) and then transferred them to a medium containing 14N. Which of the above results would be expected after one DNA replication in the presence of 14N?
  • 24. 
    Which enzyme catalyzes the elongation of a DNA strand in the 5'  3' direction?
    • A. 

      Primase

    • B. 

      DNA ligase

    • C. 

      DNA polymerase

    • D. 

      Topoisomerase

    • E. 

      Helicase

  • 25. 
    A space probe returns with a culture of a microorganism found on a distant planet. Analysis shows that it is a carbon-based life-form that has DNA. You grow the cells in 15N medium for several generations and then transfer them to 14N medium. Which pattern in Figure 16.1 would you expect if the DNA was replicated in a conservative manner?
  • 26. 
    What determines the nucleotide sequence of the newly synthesized strand during DNA replication?
    • A. 

      The particular DNA polymerase catalyzing the reaction

    • B. 

      The relative amounts of the four nucleoside triphosphates in the cell

    • C. 

      The nucleotide sequence of the template strand

    • D. 

      The primase used in the reaction

    • E. 

      Both A and D

  • 27. 
    What is the function of DNA polymerase?
    • A. 

      To unwind the DNA helix during replication

    • B. 

      To seal together the broken ends of DNA strands

    • C. 

      To add nucleotides to the end of a growing DNA strand

    • D. 

      To degrade damaged DNA molecules

    • E. 

      To rejoin the two DNA strands (one new and one old) after replication

  • 28. 
    Which of the following is least related to the others on the list?
    • A. 

      Okazaki fragments

    • B. 

      Replication fork

    • C. 

      Telomerase

    • D. 

      DNA polymerase

    • E. 

      Semiconservative model

  • 29. 
    You briefly expose bacteria undergoing DNA replication to radioactively labeled nucleotides. When you centrifuge the DNA isolated from the bacteria, the DNA separates into two classes. One class of labeled DNA includes very large molecules (thousands or even millions of nucleotides long), and the other includes short stretches of DNA (several hundred to a few thousand nucleotides in length). These two classes of DNA probably represent
    • A. 

      Leading strands and Okazaki fragments.

    • B. 

      Lagging strands and Okazaki fragments

    • C. 

      Okazaki fragments and RNA primers.

    • D. 

      Leading strands and RNA primers.

    • E. 

      RNA primers and mitochondrial DNA.

  • 30. 
  • 31. 
    Refer to the following list of enzymes to answer the following questions. The answers may be used once, more than once, or not at all.                   A.     helicase                 B.     nuclease                 C.     ligase                 D.     DNA polymerase I                 E.      primase   separates the DNA strands during replication
  • 32. 
    Refer to the following list of enzymes to answer the following questions. The answers may be used once, more than once, or not at all.                   A.     helicase                 B.     nuclease                 C.     ligase                 D.     DNA polymerase I                 E.      primase   covalently connects segments of DNA
  • 33. 
    Refer to the following list of enzymes to answer the following questions. The answers may be used once, more than once, or not at all.                   A.     helicase                 B.     nuclease                 C.     ligase                 D.     DNA polymerase I                 E.      primase   synthesizes short segments of RNA
  • 34. 
    Refer to the following list of enzymes to answer the following questions. The answers may be used once, more than once, or not at all.                   A.     helicase                 B.     nuclease                 C.     ligase                 D.     DNA polymerase I                 E.      primase   DNA-cutting enzymes used in the repair of DNA damage
  • 35. 
    The difference between ATP and the nucleoside triphosphates used during DNA synthesis is that
    • A. 

      The nucleoside triphosphates have the sugar deoxyribose; ATP has the sugar ribose.

    • B. 

      The nucleoside triphosphates have two phosphate groups; ATP has three phosphate groups.

    • C. 

      ATP contains three high-energy bonds; the nucleoside triphosphates have two.

    • D. 

      ATP is found only in human cells; the nucleoside triphosphates are found in all animal and plant cells.

    • E. 

      Triphosphate monomers are active in the nucleoside triphosphates, but not in ATP.

  • 36. 
    The Y-shaped structure where the DNA double helix is actively unwound during DNA replication is called the
    • A. 

      Replication fork.

    • B. 

      Replication Y.

    • C. 

      Elongation junction.

    • D. 

      Unwinding point.

    • E. 

      Y junction.

  • 37. 
    The leading and the lagging strands differ in that 
    • A. 

      The leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction

    • B. 

      The leading strand is synthesized by adding nucleotides to the 3' end of the growing strand, and the lagging strand is synthesized by adding nucleotides to the 5' end.

    • C. 

      The leading strand is synthesized continuously, whereas the lagging strand is synthesized in short fragments that are ultimately stitched together.

    • D. 

      Both A and B

    • E. 

      Both A and C

  • 38. 
    • A. 

      A nucleoside triphosphate is added to the 5' end of the DNA, releasing a molecule of pyrophosphate.

    • B. 

      A nucleoside triphosphate is added to the 3' end of the DNA, releasing a molecule of pyrophosphate.

    • C. 

      A nucleoside diphosphate is added to the 5' end of the DNA, releasing a molecule of phosphate.

    • D. 

      A nucleoside diphosphate is added to the 3' end of the DNA, releasing a molecule of phosphate.

    • E. 

      A nucleoside monophosphate is added to the 3' end of the DNA.

  • 39. 
    A new DNA strand elongates only in the 5' to 3' direction because
    • A. 

      DNA polymerase begins adding nucleotides at the 5' end of the template.

    • B. 

      Okazaki fragments prevent elongation in the 3' to 5' direction.

    • C. 

      The polarity of the DNA molecule prevents addition of nucleotides at the 3' end.

    • D. 

      Replication must progress toward the replication fork.

    • E. 

      DNA polymerase can only add nucleotides to the free 3' end.

  • 40. 
    Replicating the lagging strand of DNA-that is, adding bases in the 3'  5' direction-utilizes which of the following?
    • A. 

      DNA ligase

    • B. 

      RNA primers

    • C. 

      Okazaki fragments

    • D. 

      A and B only

    • E. 

      A, B, and C

  • 41. 
    What kind of molecule or substance is the primer that is used to initiate the synthesis of a new DNA strand?
    • A. 

      RNA

    • B. 

      DNA

    • C. 

      Protein

    • D. 

      Phosphate

    • E. 

      Sulfur

  • 42. 
    What is the function of topoisomerase?
    • A. 

      Relieving strain in the DNA ahead of the replication fork

    • B. 

      Elongation of new DNA at a replication fork by addition of nucleotides to the existing chain

    • C. 

      The addition of methyl groups to bases of DNA

    • D. 

      Unwinding of the double helix

    • E. 

      Stabilizing single-stranded DNA at the replication fork

  • 43. 
    What is the role of DNA ligase in the elongation of the lagging strand during DNA replication?
    • A. 

      Synthesize RNA nucleotides to make a primer

    • B. 

      Catalyze the lengthening of telomeres

    • C. 

      Join Okazaki fragments together

    • D. 

      Unwind the parental double helix

    • E. 

      Stabilize the unwound parental DNA

  • 44. 
    All of the following are functions of DNA polymerase in DNA replication except
    • A. 

      Covalently adding nucleotides to the new strands.

    • B. 

      Proofreading each added nucleotide for correct base pairing.

    • C. 

      Replacing RNA primers with DNA.

    • D. 

      Initiating a polynucleotide strand.

    • E. 

      None of the above

  • 45. 
    Which of the following help to hold the DNA strands apart while they are being replicated?
    • A. 

      Primase

    • B. 

      Ligase

    • C. 

      DNA polymerase

    • D. 

      Single-strand binding proteins

    • E. 

      Exonuclease

  • 46. 
    Which of these mechanisms ensures that the DNA sequence in the genome remains accurate?
    • A. 

      Proofreading during DNA replication

    • B. 

      Mismatch repair

    • C. 

      Excision repair

    • D. 

      Complementary base pairing during DNA replication

    • E. 

      All of the above

  • 47. 
    Individuals with the disorder xeroderma pigmentosum are hypersensitive to sunlight because their cells have an impaired ability to 
    • A. 

      Replicate DNA.

    • B. 

      Undergo mitosis.

    • C. 

      Exchange DNA with other cells.

    • D. 

      Repair thymine dimers.

    • E. 

      Recombine homologous chromosomes during meiosis.

  • 48. 
    Which of the following is analogous to telomeres?
    • A. 

      The pull tab on a soft drink can

    • B. 

      The two ends of a shoelace

    • C. 

      The central spindle that a CD fits around while in the case

    • D. 

      The mechanism of a zipper that allows the separated parts to be joined

    • E. 

      The correct letters used to replace errors in a document after they have been deleted in a word processor

  • 49. 
    A eukaryotic cell lacking telomerase would
    • A. 

      Have a high probability of becoming cancerous.

    • B. 

      Produce Okazaki fragments.

    • C. 

      Be unable to repair thymine dimers.

    • D. 

      Undergo a reduction in chromosome length.

    • E. 

      Be highly sensitive to sunlight.

  • 50. 
    Which of the following statements about telomeres is correct?
    • A. 

      They contain multiple copies of a short RNA sequence.

    • B. 

      They are present at the ends of eukaryotic chromosomes.

    • C. 

      They can be extended by an enzyme called telomerase.

    • D. 

      Both A and B

    • E. 

      Both B and C

  • 51. 
    Garrod hypothesized that "inborn errors of metabolism" such as alkaptonuria occur because
    • A. 

      Genes dictate the production of specific enzymes, and affected individuals have genetic defects that cause them to lack certain enzymes.

    • B. 

      Enzymes are made of DNA, and affected individuals lack DNA polymerase.

    • C. 

      Many metabolic enzymes use DNA as a cofactor, and affected individuals have mutations that prevent their enzymes from interacting efficiently with DNA.

    • D. 

      Certain metabolic reactions are carried out by ribozymes, and affected individuals lack key splicing factors.

    • E. 

      Metabolic enzymes require vitamin cofactors, and affected individuals have significant nutritional deficiencies.

  • 52. 
    We now know that the one gene-one enzyme hypothesis is not entirely accurate because
    • A. 

      Many genes code for proteins that are not enzymes.

    • B. 

      A single gene codes for a single polypeptide chain, and many enzymes are made up of more than one polypeptide chain.

    • C. 

      Many genes code for RNA molecules that have no enzymatic activity.

    • D. 

      A and B only

    • E. 

      A, B, and C

  • 53. 
    Which of the following represents a similarity between RNA and DNA?
    • A. 

      Both are double-stranded.

    • B. 

      The presence of uracil

    • C. 

      The presence of an OH group on the 2' carbon of the sugar

    • D. 

      Nucleotides consisting of a phosphate, sugar, and nitrogenous base

    • E. 

      Both are found exclusively in the nucleus.

  • 54. 
    The nitrogenous base adenine is found in all members of which group?
    • A. 

      Proteins, triglycerides, and testosterone

    • B. 

      Proteins, ATP, and DNA

    • C. 

      ATP, RNA, and DNA

    • D. 

      Alpha glucose, ATP, and DNA

    • E. 

      Proteins, carbohydrates, and ATP

  • 55. 
    Using RNA as a template for protein synthesis instead of translating proteins directly from the DNA is advantageous for the cell because
    • A. 

      RNA is much more stable than DNA.

    • B. 

      RNA acts as an expendable copy of the genetic material, allowing the DNA to serve as a permanent, pristine repository of the genetic material.

    • C. 

      Many mRNA molecules can be transcribed from a single gene, increasing the potential rate of gene expression.

    • D. 

      B and C only

    • E. 

      A, B, and C

  • 56. 
    If proteins were composed of only 12 different kinds of amino acids, what would be the smallest possible codon size in a genetic system with four different nucleotides?
    • A. 

      1

    • B. 

      2

    • C. 

      3

    • D. 

      4

    • E. 

      12

  • 57. 
    • A. 

      5

    • B. 

      10

    • C. 

      25

    • D. 

      64

    • E. 

      32

  • 58. 
    The enzyme polynucleotide phosphorylase randomly assembles nucleotides into a polynucleotide polymer. You add polynucleotide phosphorylase to a solution of adenosine triphosphate and guanosine triphosphate. The resulting artificial mRNA molecule would have ________ possible different codons if the code involved two-base sequences and ________ possible different codons if the code involved three-base sequences.
    • A. 

      2; 3

    • B. 

      2; 4

    • C. 

      4; 8

    • D. 

      4; 16

    • E. 

      16; 64

  • 59. 
    A particular triplet of bases in the template strand of DNA is AGT. The corresponding codon for the mRNA transcribed is
    • A. 

      AGT.

    • B. 

      UGA.

    • C. 

      TCA.

    • D. 

      ACU.

    • E. 

      Either UCA or TCA, depending on wobble in the first base

  • 60. 
    • A. 

      5' TTG-CTA-CAG-TAG 3'.

    • B. 

      3' AAC-GAC-GUC-AUA 5'.

    • C. 

      5' AUG-CTG-CAG-TAT 3'.

    • D. 

      3' AAA-AAT-ATA-ACA 5'.

    • E. 

      3' AAA-GAA-TAA-CAA 5'.

  • 61. 
    What amino acid sequence will be generated, based on the following mRNA codon sequence? 5'AUG-UCU-UCG-UUA-UCC-UUG
    • A. 

      Met-arg-glu-arg-glu-arg

    • B. 

      Met-glu-arg-arg-gln-leu

    • C. 

      Met-ser-leu-ser-leu-ser

    • D. 

      Met-ser-ser-leu-ser-leu

    • E. 

      Met-leu-phe-arg-glu-glu

  • 62. 
    A peptide has the sequence NH2-phe-pro-lys-gly-phe-pro-COOH. Which of the following sequences in the coding strand of the DNA codes for this peptide?
    • A. 

      3' UUU-CCC-AAA-GGG-UUU-CCC

    • B. 

      3' AUG-AAA-GGG-TTT-CCC-AAA-GGG

    • C. 

      5' TTT-CCC-AAA-GGG-TTT-CCC

    • D. 

      5' GGG-AAA-TTT-AAA-CCC-ACT-GGG

    • E. 

      5' ACT-TAC-CAT-AAA-CAT-TAC-UGA

  • 63. 
    What is the sequence of a peptide based on the mRNA sequence 5' UUUUCUUAUUGUCUU 3' ?
    • A. 

      Leu-cys-tyr-ser-phe

    • B. 

      Cyc-phe-tyr-cys-leu

    • C. 

      Phe-leu-ile-met-val

    • D. 

      Leu-pro-asp-lys-gly

    • E. 

      Phe-ser-tyr-cys-leu

  • 64. 
    Suppose the following DNA sequence was mutated from 3' AGAGAGAGAGAGAGAGAG 5' to  3' AGAAGAGAGATCGAGAGA 5'. What amino acid sequence will be generated based on this mutated DNA?
    • A. 

      Arg-glu-arg-glu-arg-glu

    • B. 

      Glu-arg-glu-leu-leu-leu

    • C. 

      Ser-leu-ser-leu-ser-leu

    • D. 

      Ser-ser-leu

    • E. 

      Leu-phe-arg-glu-glu-glu

  • 65. 
    • A. 

      3

    • B. 

      100

    • C. 

      300

    • D. 

      900

    • E. 

      1,800

  • 66. 
    A codon
    • A. 

      Consists of two nucleotides.

    • B. 

      May code for the same amino acid as another codon

    • C. 

      Consists of discrete amino acid regions.

    • D. 

      Catalyzes RNA synthesis.

    • E. 

      Is found in all eukaryotes, but not in prokaryotes.

  • 67. 
    If the triplet CCC codes for the amino acid proline in bacteria, then in plants CCC should code for
    • A. 

      Leucine.

    • B. 

      Valine.

    • C. 

      Cystine.

    • D. 

      Phenylalanine.

    • E. 

      Proline.

  • 68. 
    The genetic code is essentially the same for all organisms. From this, one can logically assume all of the following except
    • A. 

      A gene from an organism could theoretically be expressed by any other organism.

    • B. 

      All organisms have a common ancestor.

    • C. 

      DNA was the first genetic material.

    • D. 

      The same codons in different organisms usually translate into the same amino acids.

    • E. 

      Different organisms have the same number of different types of amino acids.

  • 69. 
    Which of the following is true for both prokaryotic and eukaryotic gene expression?
    • A. 

      After transcription, a 3' poly-A tail and a 5' cap are added to mRNA.

    • B. 

      Translation of mRNA can begin before transcription is complete.

    • C. 

      RNA polymerase binds to the promoter region to begin transcription.

    • D. 

      MRNA is synthesized in the 3' → 5' direction.

    • E. 

      The mRNA transcript is the exact complement of the gene from which it was copied

  • 70. 
    Which of the following are transcribed from DNA?
    • A. 

      Protein

    • B. 

      Exons

    • C. 

      RRNA

    • D. 

      B and C only

    • E. 

      A, B, and C

  • 71. 
    RNA polymerase and DNA polymerase differ in that
    • A. 

      RNA polymerase uses RNA as a template, and DNA polymerase uses a DNA template.

    • B. 

      RNA polymerase binds to single-stranded DNA, and DNA polymerase binds to double-stranded DNA.

    • C. 

      RNA polymerase is much more accurate than DNA polymerase.

    • D. 

      RNA polymerase can initiate RNA synthesis, but DNA polymerase requires a primer to initiate DNA synthesis.

    • E. 

      RNA polymerase does not need to separate the two strands of DNA in order to synthesize an RNA copy, whereas DNA polymerase must unwind the double helix before it can replicate the DNA.

  • 72. 
    Which of the following is not a part of the eukaryotic transcription initiation complex?
    • A. 

      Promoter

    • B. 

      RNA polymerase

    • C. 

      Transcription factors

    • D. 

      SnRNP

    • E. 

      TATA box

  • 73. 
    Which of the following is least related to the other items?
    • A. 

      Translation

    • B. 

      TATA box

    • C. 

      Transcription

    • D. 

      Template strand

    • E. 

      RNA polymerase II

  • 74. 
    Which of the following statements best describes the termination of transcription in prokaryotes?
    • A. 

      RNA polymerase transcribes through the polyadenylation signal, causing proteins to associate with the transcript and cut it free from the polymerase

    • B. 

      RNA polymerase transcribes through the terminator sequence, causing the polymerase to fall off the DNA and release the transcript.

    • C. 

      RNA polymerase transcribes through an intron, and the snRNPs cause the polymerase to let go of the transcript.

    • D. 

      Once transcription has initiated, RNA polymerase transcribes until it reaches the end of the chromosome.

    • E. 

      RNA polymerase transcribes through a stop codon, causing the polymerase to stop advancing through the gene and release the mRNA.

  • 75. 
    RNA polymerase moves along the template strand of DNA in the ________ direction, and adds nucleotides to the ________ end of the growing transcript.
    • A. 

      3' to 5'; 5'

    • B. 

      3' to 5'; 3'

    • C. 

      5' to 3'; 5'

    • D. 

      5' to 3'; 3'

  • 76. 
    All of the following are found in prokaryotic mRNA except
    • A. 

      The AUG codon.

    • B. 

      The UGA codon.

    • C. 

      Introns.

    • D. 

      Uracil.

    • E. 

      Cytosine.

  • 77. 
    Which of the following helps to stabilize mRNA by inhibiting its degradation?
    • A. 

      TATA box

    • B. 

      Spliceosomes

    • C. 

      5' cap

    • D. 

      Poly-A tail

    • E. 

      Both C and D

  • 78. 
    What is a ribozyme?
    • A. 

      An enzyme that uses RNA as a substrate

    • B. 

      An enzyme made up of RNA

    • C. 

      An enzyme that catalyzes the association between the large and small ribosomal subunits

    • D. 

      An enzyme that synthesizes RNA as part of the transcription process

    • E. 

      An enzyme that synthesizes RNA primers during DNA replication

  • 79. 
    What are the coding segments of a stretch of eukaryotic DNA called?
    • A. 

      Introns

    • B. 

      Exons

    • C. 

      Codons

    • D. 

      Replicons

    • E. 

      Transposons

  • 80. 
    A transcription unit that is 8,000 nucleotides long may use 1,200 nucleotides to make a protein consisting of 400 amino acids. This is best explained by the fact that
    • A. 

      Many noncoding nucleotides are present in mRNA.

    • B. 

      There is redundancy and ambiguity in the genetic code.

    • C. 

      Many nucleotides are needed to code for each amino acid.

    • D. 

      Nucleotides break off and are lost during the transcription process.

    • E. 

      There are termination exons near the beginning of mRNA.

  • 81. 
    Once transcribed, eukaryotic mRNA typically undergoes substantial alteration that includes
    • A. 

      Excision of introns.

    • B. 

      Fusion into circular forms known as plasmids.

    • C. 

      Linkage to histone molecules.

    • D. 

      Union with ribosomes.

    • E. 

      Fusion with other newly transcribed mRNA.

  • 82. 
    Introns are significant to biological evolution because
    • A. 

      Their presence allows exons to be moved around more easily, creating proteins with new combinations of functional domains.

    • B. 

      They protect the mRNA from degeneration.

    • C. 

      They are translated into essential amino acids.

    • D. 

      They maintain the genetic code by preventing incorrect DNA base pairings.

    • E. 

      They correct enzymatic alterations of DNA bases.

  • 83. 
    A mutation in which of the following parts of a gene is likely to be most damaging to a cell?
    • A. 

      Intron

    • B. 

      Exon

    • C. 

      5' UTR

    • D. 

      3' UTR

    • E. 

      All would be equally damaging.

  • 84. 
    Which of the following is (are) true of snRNPs?
    • A. 

      They are made up of both protein and RNA.

    • B. 

      They bind to splice sites at each end of the intron.

    • C. 

      They join together to form a large structure called the spliceosome.

    • D. 

      Only A and C are true.

    • E. 

      A, B, and C are true

  • 85. 
    During splicing, which molecular component of the spliceosome catalyzes the excision reaction?
    • A. 

      RNA

    • B. 

      DNA

    • C. 

      Protein

    • D. 

      Lipid

    • E. 

      Sugar

  • 86. 
    Alternative RNA splicing
    • A. 

      Is a mechanism for increasing the rate of transcription.

    • B. 

      Can allow the production of proteins of dramatically different sizes from a single mRNA.

    • C. 

      Can allow the production of proteins of dramatically different amino acid sequences from a single mRNA.

    • D. 

      B and C only

    • E. 

      A, B, and C

  • 87. 
    Which of the following is least related to the other items?
    • A. 

      SnRNP

    • B. 

      Triplet code

    • C. 

      Wobble

    • D. 

      TRNA

    • E. 

      Anticodon

  • 88. 
    All of the following are directly involved in translation except
    • A. 

      MRNA.

    • B. 

      TRNA.

    • C. 

      Ribosomes.

    • D. 

      DNA.

    • E. 

      Aminoacyl-tRNA synthetase enzymes.

  • 89. 
    A particular triplet of bases in the coding sequence of DNA is AAA. The anticodon on the tRNA that binds the mRNA codon is
    • A. 

      TTT.

    • B. 

      UUA.

    • C. 

      UUU.

    • D. 

      AAA.

    • E. 

      Either UAA or TAA, depending on first base wobble.

  • 90. 
    Accuracy in the translation of mRNA into the primary structure of a protein depends on specificity in the
    • A. 

      Binding of ribosomes to mRNA.

    • B. 

      Shape of the A and P sites of ribosomes.

    • C. 

      Bonding of the anticodon to the codon.

    • D. 

      Attachment of amino acids to tRNAs.

    • E. 

      Both C and D

  • 91. 
    What is an anticodon part of?
    • A. 

      DNA

    • B. 

      TRNA

    • C. 

      MRNA

    • D. 

      A ribosome

    • E. 

      An activating enzyme

  • 92. 
    What type of bonding is responsible for maintaining the shape of the tRNA molecule?
    • A. 

      Covalent bonding between sulfur atoms

    • B. 

      Ionic bonding between phosphates

    • C. 

      Hydrogen bonding between base pairs

    • D. 

      Van der Waals interactions between hydrogen atoms

    • E. 

      Peptide bonding between amino acids

  • 93. 
    • A. 

      UGG

    • B. 

      GUG

    • C. 

      GUA

    • D. 

      UUC

    • E. 

      CAU

  • 94. 
    A mutant bacterial cell has a defective aminoacyl synthetase that attaches a lysine to tRNAs with the anticodon AAA instead of a phenylalanine. The consequence of this for the cell will be that
    • A. 

      None of the proteins in the cell will contain phenylalanine.

    • B. 

      Proteins in the cell will include lysine instead of phenylalanine at amino acid positions specified by the codon UUU.

    • C. 

      The cell will compensate for the defect by attaching phenylalanine to tRNAs with lysine-specifying anticodons.

    • D. 

      The ribosome will skip a codon every time a UUU is encountered.

    • E. 

      None of the above will occur; the cell will recognize the error and destroy the tRNA.

  • 95. 
    There are 61 mRNA codons that specify an amino acid, but only 45 tRNAs.  This is best explained by the fact that 
    • A. 

      Some tRNAs have anticodons that recognize two or more different codons.

    • B. 

      The rules for base pairing between the third base of a codon and tRNA are flexible.

    • C. 

      Many codons are never used, so the tRNAs that recognize them are dispensable.

    • D. 

      A and B only

    • E. 

      A, B, and C

  • 96. 
    What are ribosomes composed of?
    • A. 

      RRNA only

    • B. 

      Proteins only

    • C. 

      Both rRNA and protein

    • D. 

      MRNA, rRNA, and protein

    • E. 

      MRNA, tRNA, rRNA, and protein

  • 97. 
    Where is eukaryotic ribosomal RNA transcribed?
    • A. 

      The Golgi apparatus

    • B. 

      Ribosomes

    • C. 

      The nucleolus

    • D. 

      X chromosomes

    • E. 

      Prokaryotic cells only

  • 98. 
    What is the most abundant type of RNA?
    • A. 

      MRNA

    • B. 

      TRNA

    • C. 

      RRNA

    • D. 

      Pre-mRNA

    • E. 

      HnRNA