Microbiology 2124
Final Exam
Dec. 10, 1998
David Demezas

General Instructions: Multiple Choice. Choose the most correct answer and mark the corresponding letter on your scantron answer sheet.

1. Which of the following is unique to eukaryotic organisms (i.e., never found in prokaryotic organisms)?
A. A plasma membrane
B. Ribosomes
C. A cell wall
D. A membrane-bound nucleus
E. Enzymes

2. Which of the following is (are) required for bacteria to survive and grow?
A. Transcription
B. Translation
C. Replication
D. All of the above
E. None of the above.

3. True (A) or False (B). The cell is the fundamental unit of all living matter.

4. Which of the following scientist disproved the "theory of spontaneous generation"?
A. A. van Leeuwenhoek
B. L. Pasteur
C. R. Koch
D. R. Petri
E. W. Hesse

5. Which of the following pairs of sugars are the sugar backbone in the peptidoglycan layer?
A. Sucrose and Fructose
B. ribose and deoxyribose
C. N-acetyl glucosamine and glucose
D. N-acetyl muramic acid and fructose
E. N-acetyl glucosamine and N-acetyl muramic acid

6. The rigidity and shape of a bacterium is due to the _____.
A. cell membrane
B. peptidoglycan layer
C. the lipopolysaccharide
D. the teichoic acid layer
E. the flagella

7. Which of the following is NOT characteristic of a cell's cytoplasmic membrane?
A. a phospholipid bilayer
B. a highly selective permeability barrier
C. a hydrophobic core and hydrophilic layers on the outside
D. a very rigid (i.e., stiff) membrane
E. integral proteins that span the membrane

8. True (A) or False (B). Active transporters require some form of energy to transport molecules across the plasma membrane.

9. Which of the following enzymes would NOT be found in the periplasmic space of a Gram-negative bacteria?
A. lysozyme
B. transport proteins
C. chemoreceptors
D. hydrolytic enzymes

10. The above figure best illustrates the cell wall of __________.
A. a Gram - positive cell
B. protozoa
C. fungi
D. an Archaea cell
E. a Gram - negative cell

11. A sugar is chemically altered as it is transported across the cytoplasmic membrane into a cell. This is referred to as ____________.
A. group translocation
B. active transport
C. simple diffusion
D. osmosis
E. facilitated diffusion

12. The proton motive force may be used to ___________.
A. drive the flagella
B. generate ATP
C. transport molecules across the cytoplasmic membrane
D. reverse electron flow to generate NADPH
E. all of the above

13. Which of the following types of metabolism does Not generate a proton motive force that can be used to generate ATP?
A. aerobic respiration
B. anaerobic respiration
C. phototrophic
D. alcohol fermentation
E. chemolithotrophy

14. Which of the following best sums the result of aerobic respiration beginning with a molecule of glucose?
A. 2 x CO₂; 2 ATPs; 2 x ethanol
B. 2 x lactate; 2 ATPs
C. 2 x ethanol; 4 ATPs
D. 2 x pyruvate ; 4 ATPs
E. 6 x CO₂; 38 ATPs

15. Phototrophic bacteria generate ATP using _________ .
A. non cyclic photophosphorylation
B. oxidative phosphorylation
C. cyclic photophosphorylation
D. substrate level photophosphorylation
E. substrate level phosphorylation

16. Which of the following molecules cannot be used as a terminal electron acceptor in anaerobic respiration?
A. SO₄^2-
B. NO₃^-
C. CO₂
D. H₂S
E. All of the above.

17. Which of the following elements makes up the largest percentage of the dry weight of a cell?
A. oxygen
B. nitrogen
C. carbon
D. phosphorous
E. sulfur

18. True (A) or False (B). A complex medium is chemically undefined.

19. The end products of glycolysis are _______.
A. CO₂ and ATP
B. pyruvate, NADH and ATP
C. CO₂, pyruvate, NADH and ATP
D. CO₂, and NADH
E. ethanol and CO₂

Oxidation - reduction couple	Eo'
2 H+ + 2 e- ----> H2	-420 mV
1/2O2 + 2e- + 2H+ ----->H2O	+820 mV

20. True (A) or False (B). Given the above table and the following chemical equation: H₂ + 1/2 O₂ ------> H₂O. H₂ is the electron acceptor and O₂ is the electron donor.

21. Bacteria multiply by a process called _________.
A. meiosis
B. binary fission
C. replication
D. mitosis
E. fusion

22. You are given a culture with 10⁸ cells per ml of medium. What would be the population size of this culture after 6 generations?
A. 2 x 10⁹ cells per ml.
B. 8 x 10⁹ cells per ml.
C. 2 x 10⁸ cells per ml.
D. 6.4 x 10⁹ cells per ml.
E. 10¹⁴ cells per ml.

23. Which of the following is NOT characteristic of stationary phase?
A. Growth rate equals zero.
B. Nutrients are depleted.
C. Waste products are accumulating.
D. Growth rate is maximal for the species of bacteria.
E. All of the above.

24. Which of the following techniques counts both live and dead cells?
A. Spread plates
B. Pour plates
C. Turbidity
D. Direct microscopic counts
E. C and D

25. "Central dogma of molecular biology" states that genetic information flows from _____
A. RNA through DNA to protein.
B. protein through RNA to DNA
C. DNA through protein to RNA
D. DNA through RNA to protein
E. RNA through protein to DNA

26. The primer in DNA replication is _________.
A. an RNA starter sequence with a free 3´-OH group
B. an RNA starter sequence with a free 5´-OH group
C. a DNA starter sequence with a free 3´-OH group
D. a DNA starter sequence with a free 5´-OH group
E. a DNA starter sequence with a free 5´-phosphate group

27. Which of the following statements about RNA is False?
A. mRNA, tRNA and rRNA are the products of transcription.
B. rRNA is incorporated into ribosomes.
C. All RNAs are translated into polypeptides.
D. tRNAs carry amino acids to the growing polypeptide.
E. Only mRNA is translated into polypeptides.

28. Enzymatic activity of a pathway (e.g., biosynthesis of an amino acid) can be controlled by the endproduct inhibiting the first enzyme of the pathway. This is referred to as _________.
A. saturation
B. negative control
C. positive control
D. substrate inhibition
E. feedback inhibition

29. Repressors (e.g., lac repressor) and the catabolite activator protein are examples of ____________.
A. catalytic enzymes
B. allosteric proteins
C. terminators
D. coinducers

30. Which of the following statements is False about cells in the early part of the second phase of diauxic growth in a glucose/lactose based medium?
A. The lac repressor is bound to the inducer and cannot bind to the operator region.
B. The levels of cyclic AMP are elevated relative to the first phase of growth.
C. The lac operon is induced.
D. cAMP/CAP is bound to the CAP binding site.
E. All of the above statements are true.

31. Attenuation, an effective means of regulating amino acid biosynthetic genes in bacteria, requires _________.
A. a repressor
B. a activator protein
C. coupling of transcription and translation
D. an inducer
E. feedback inhibition

32. Which of the following pair is NOT correctly matched?
1. Transformation / Bacteriophage-mediated DNA transfer cell
2. Transduction / Uptake of DNA from the environment
3. Hfr / F-factor is integrated in chromosome
4. F ⁺ / F-factor separate from chromosome
5. F ^- / Recipient cell
A. 2 and 3
B. 1 and 5
C. 1 and 2
D. 2 and 4
E. 3 and 4

33. You have been bothered by food spoilage in the crisper drawer of your refrigerator. Most likely the microbial culprit is a/an ______.
A. psychrophile
B. mesophile
C. barophile
D. acidophile
E. thermophile

34. You have isolated a marine bacterium and verified its requirement for the marine environment for growth. You conclude that this bacterium is a/an _______.
A. osmophile
B. halophile
C. xerophile
D. none of the above

35. Which of the following is responsible for attaching nucleotides to the growing end of a DNA strand and proofreading each inserted nucleotide?
A. DNA helicase
B. DNA gyrase
C. DNA ligase
D. DNA polymerase III
E. None of the above

36. True (A) or False (B). Okazaki fragments are found on the leading strand during DNA replication.

37. Which of the following is a characteristic of the lagging strand synthesis?
A. Continuous synthesis of the lagging strand.
B. Synthesis of the lagging strand without a template strand.
C. The lagging strand is made without DNA polymerase.
D. Multiple RNA primers are needed for the lagging strand's synthesis.
E. All of the above are characteristic of lagging strand synthesis.

38. True (A) or False (B). A missense mutation results in a change in the amino acid sequence of a polypeptide; a silent mutation does not.

39. A codon is a sequence of three nucleotides coded for by __________.
A. DNA
B. messenger RNA (mRNA)
C. transfer RNA (tRNA)
D. ribosomal RNA (rRNA)
E. proteins

40. The Ames test uses auxotrophs with ________.
A. large deletions
B. microinsertions
C. temperature sensitive mutations
D. point mutations
E. transposon-induced mutations

41. Which of the following do Not include anoxygenic phototrophic species of bacteria?
A. Green sulfur bacteria
B. Green non sulfur bacteria
C. Purple non sulfur bacteria
D. Purple sulfur bacteria
E. Cyanobacteria

42. Nitrifiers carry out which of the following ecological functions in soils?
A. The reduction of ammonia to nitrate
B. The oxidation of methane to methanol
C. The reduction of sulfate to sulfide
D. The oxidation of ammonia to nitrate
E. The oxidation of hydrogen gas to protons

43. Which of the following is a Gram-positive, endospore-forming microorganism that produces an insecticidal protein?
A. Pseudomonas sp.
B. Azotobacter sp.
C. Bacillus sp.
D. Chromobacterium sp.
E. Klebsiella sp.

44. Escherichia, Enterobacter, Shigella, and Salmonella are all members of the group of bacteria called _______.
A. colonic bacteria
B. stomach bacteria
C. enteric bacteria
D. hemmorhagic bacteria
E. planktonic bacteria

45. True (A) or False (B) Cyanobacteria (Blue-green bacteria) are oxygenic phototrophs.

46. True (A) or False (B). Bacteriorhodopson is a membrane-associated protein that plays an integral role in the generation of the proton motive force in Halobacterium.

47. All hyperthermophilic Archaea have a temperature optimum of ______.
A. between 50 and 80^oC
B. above 80^oC
C. below 50^oC

48. True (A) or False (B). Extreme halophilic Archaea require at least 1.5 M (9% w/v) salt for growth.

49. True (A) or False (B). Most species of algae carry out oxygenic photosynthesis.

50. Which type(s) of metabolism is/are found in the fungi?
A. photoautotrophy
B. chemolithotrophy
C. chemoorganotrophy
D. photoheterotrophy
E. A, C, and D

51. Which of the following fungi does Not produce spores?
A. Deuteromycetes
B. Oomycetes
C. Zygomycetes
D. Basidiomycetes
E. Ascomycetes

52. Which of the following is an asexual spore?
A. basidiospore
B. ascospore
C. conidia
D. oospore
E. zygospore

53. Slime molds and protozoa obtain their food by _______.
A. photosynthesis
B. phagocytosis
C. transduction
D. osmosis
E. absorption

54. Which of the following viruses is/are a male-specific virus(es) that attach to the F-pili?
A. MS2
B. lambda
C. M13
D. lambda and M13
E. MS2 and M13

55. The temperate virus lambda DNA may integrate into the host bacterium's chromosome. Lambda is now referred to as a _________.
A. lysogen
B. prophage
C. plasmid
D. cosmid
E. transposon

56. Which two proteins play a central role in the decision whether lambda phage enters the lysogenic state or the lytic cycle?
A. cro and CI (lambda repressor)
B. cro and N
C. CII and N
D. CII and CIII E. N and CIII

57. True (A) or False (B). Virions are extremely infectious during the eclipse period of viral replication.

58. Bacteria have evolved _________ to defend against infection by bacteriophages by digesting the incoming viral DNA.
A. hydrogenases
B. topoisomerases
C. ligases
D. DNA polymerases
E. restriction endonucleases

59. The enzyme _________ comes from Thermus aquaticus and has revolutionized molecular biology in many ways.
A. Taq DNA polymerase
B. Taq RNA polymerase
C. Taq ligase
D. Taq restriction endonuclease
E. None of the above.

60. True (A) or False (B). Secondary metabolites are produced during the lag phase of growth.

61. True (A) or False (B). Fimbriae and the glycocalyx are major adherence factors facilitating the attachment of microbial pathogens to host tissue.

62. Which of the following is Not an enzyme associated with the invasion of the host by a bacterial pathogen?
A. hyluronidase
B. transferrin
C. collagenase
D. hemolysins
E. streptokinase

63. True (A) or False (B). Both host specificity and tissue specificity are important factors in the establishment of an infection by a pathogen in a host.

64. Which of the following is Not a exotoxin?
A. the cholera toxin
B. the tetanus toxin
C. the diphtheria toxin
D. the LPS of Salmonella
E. the botulinum toxin

65. _______ are exotoxins that act on the small intestine and cause massive fluid loss and diarrhea symptoms.
A. Siderophores
B. Enterotoxins
C. Transferrin
D. Hemolysins
E. None of the above.

66. In which organism is a toxin coded for by the genome of a resident phage?
A. Aspergillus niger
B. Corynebacterium diphtheriae
C. Bacillus megaterium
D. Escherichia coli
E. Staphylococcus aureus

67. Which of the following statements about toxins is false?
A. Exotoxins are generally more potent than endotoxins
B. Endotoxins are heat stable and exotoxins are heat labile.
C. Exotoxins are excreted into the surrounding environment.
D. Exotoxins rarely result in a fever; endotoxins often produce a fever in the host.
E. Endotoxins are produced by gram positive bacteria.

68. Which of the following is responsible for toxicity in Gram-negative bacteria?
A. KDO
B. Lipid A
C. Core polysaccharide
D. O-specific polysaccharide
E. Porins

69. Which of the following produces an enterotoxin that activates adenyl cyclase and a cascade of events that leads to massive loss of water and dehydration?
A. Vibrio cholerae
B. Staphylococcus aureus
C. Clostridium perfringens
D. Bacillus cereus
E. Escherichia coli

70. True (A) or False (B). Virulence, i.e., the degree of the ability of a parasite to cause disease, is determined by the invasiveness and toxigenicity of a pathogen.

71. ____ are inanimate objects, e.g., a toy, that transmit infectious agents between hosts.
A. Vectors
B. Carriers
C. Reservoirs
D. Fomites
E. Placebos

72. A mosquito transmitting malaria to a human is an example of a(n) _____.
A. endemic infection
B. biological vector
C. secondary infection
D. opportunistic pathogen
E. None of the above.

73. Diseases that occur naturally in animals, whereas man is an accidental host, are called ______.
A. epidemics
B. pandemics
C. zoonoses D. reservoirs E. carriers

74. True (A) or False (B). Transmission of infectious disease is most likely during the incubation period.

75. Typhoid Mary is an example of _____.
A. a chronic carrier
B. an acute carrier
C. an endemic
D. a pandemic
E. a famous epidemiologist

76. Which of the following is the correct order of the progression of disease.
A. Acute period, infection, incubation period, decline period, and convalescent period.
B. Infection, incubation period, acute period, decline period, and convalescent period.
C. Incubation period, acute period, decline period, infection, and convalescent period.
D. Acute period, decline period, incubation period, infection, and convalescent period
E. None of the above are correct.

77. True (A) or False (B). A common source epidemic is characterized by a sharp rise in the number of cases reported daily over a brief period of time.

78. Which of the following is the least common means of controlling epidemics?
A. Vector control
B. Immunization
C. Quarantine

79. Which of the following is Not a factor in emerging diseases?
A. Human demographics and behavior
B. Technological advances, e.g., antibiotic usage.
C. Changes in land use patterns
D. Microbial evolution
E. All of the above are factors in the emergence of new diseases.

80. True (A) or False (B). Nosocomial infections are infections contracted in a hospital.

f g I j k A B C S Z
S Happy Holidays S
f g I j k A B C S Z

Microbiology 2124
Exam 2
Oct. 21, 1998
David Demezas

General Instructions: Answer multiple choice questions on the test sheet. Answer other questions in the space provided on the test sheet. Be sure that you answer the question in complete sentences. Write your name on all pages of the test.
Multiple Choice (2.5 pts each). Choose the most correct answer and mark the corresponding letter on the blank provided to the left of the question.
1. Bacteria multiply by a process called _________.
A. meiosis
B. binary fission
C. replication
D. mitosis
E. fusion

2. The growth of a bacterial population is plotted on semilogarithmic paper. The growth curve will be _______.
A. linear
B. curvilinear
C. sigmoid
D. exponential
E. hyperbolic

3. Which of the following will NOT result in a lag phase?
A. Stationary phase cells inoculated into the same medium.
B. Damaged cells inoculated into the same medium.
C. Cell grown in rich medium inoculated into poor medium.
D. Exponentially growing cells inoculated into the same medium.
E. All of the above will result in a lag phase.

4. Which of the following is NOT characteristic of stationary phase?
A. Growth rate equals zero.
B. Nutrients are depleted.
C. Waste products are accumlating.
D. Growth rate is maximal for the species of bacteria.
E. All of the above.

5. A viable cell count is obtained by _________.
A. the spread plate method
B. the pour plate method
C. direct microscopic counts
D. optical density (i.e. turbidity)
E. A and B

6. The usual type of bacteria used in our teaching laboratory (e.g., Escherichia coli) would be classified as a ______ based on its growth temperature requirements.
A. psychrophile
B. thermophile
C. mesophile
D. extreme thermophile
E. psychrotroph

7. A species of fresh water bacteria makes _________ to counter the loss of water from their cytoplasm to the environment when they are placed in salt water.
A. reduced solutes
B. compatible solutes
C. noncompatible solutes
D. oxidized solutes
E. None of the above.

8. Which of the following enzymes degrades hydrogen peroxide to oxygen and water?
A. catalase
B. super oxide dismutase
C. peroxidase
D. reductase
E. resazurin

9. T or F - The fatty acids of the plasma membrane of a thermophilic bacteria are mainly unsaturated fatty acids

10. Microorganisms that can only grow in environments where the oxygen level is reduced from that in air are ________.
A. facultative aerobes
B. strict anaerobes
C. microaerophiles
D. aerobes
E. none of the above

11. "Central dogma of molecular biology" states that genetic information flows from _____
A. RNA through DNA to protein.
B. protein through RNA to DNA
C. DNA through protein to RNA
D. DNA through RNA to protein
E. RNA through protein to DNA

12. Nucleotides are composed of ___________.
A. a sugar, a nitrogenous base, and phosphate groups
B. a fatty acid, nitrogenous base, and sulfate groups
C. a sugar and phosphate groups
D. a peptide, nitrogenous base, and phosphate groups
E. an amino acid and phosphate groups

13. T or F - Replication in bacteria is usually bidirectional.

14. ______ forms the phosphodiester bond between adjacent Okazaki fragments.
A. DNA polymerase I
B. DNA ligase
C. DNA polymerase III
D. primase
E. topoisomerase

15 The primer in DNA replication is _________.
A. an RNA starter sequence with a free 3´-OH group
B. an RNA starter sequence with a free 5´-OH group
C. a DNA starter sequence with a free 3´-OH group
D. a DNA starter sequence with a free 5´-OH group
E. a DNA starter sequence with a free 5´-phosphate group

16. Which of the following statements about RNA is False?
A. mRNA, tRNA and rRNA are the products of transcription.
B. rRNA is incorporated into ribosomes.
C. All RNAs are translated into polypeptides.
D. tRNAs carry amino acids to the growing polypeptide.
E. Only mRNA is translated into polypeptides.

17. T or F - A tRNA may carry several different amino acids to the growing polypeptide.

18. Which of the following statements about promoters is incorrect?
A. - 10 region or the Pribnow box sequence is semiconserved among promoters
B. - 35 region is identical among all promoters.
C. -10 region is identical among all promoters.
D. - 35 region is semiconserved among all promoters.
E. B and C

For questions 19 and 20

DNA sequence: 3´ - ATG ATA CGT ACC AGT TGA CTA GTA - 5´

19. The mRNA transcript from the above DNA seqeunce is ________.
A. 3´ - ATG ATA CGT ACC AGT TGA CTA GTA - 5´
B. 5´ - TAC TAT GCA TGA TCA ACT GAT CAT - 3´
C. 5´ - UAC UAU GCA UGG UCA ACU GAU CAU - 3´
D. 5´ - ATG ATA CGT ACC AGT TGA CTA GTA - 3´
E. 3´ - UAC UAU GCA UGG UCA ACU GAU CAU - 5´

20. The translation product is _______.
A. tyr - tyr - ala - trp - ser - thr - asp - his
B. tyr - tyr - ala- stop
C. his - asp - thr - ser - trp - ala - tyr - try
D. his - asp - thr - stop
E. None of the above is correct.

21. Enzymatic activity of a pathway (e.g., biosynthesis of an amino acid) can be controlled by the endproduct inhibiting the first enzyme of the pathway. This is referred to as _________.
A. saturation
B. negative control
C. positive control
D. substrate inhibition
E. feedback inhibition

22. T or F - Regulation of a gene by a repressor is often referred to as negative control.

23. A constituitive enzyme is an enzyme in which _______.
A. synthesis is constant
B. control is negative
C. control is positive
D. there is allosteric regulation
E. there is catabolite repression

24. Repressors and the catabolite activator protein are examples of ____________.
A. catalytic enzymes
B. allosteric proteins
C. structural proteins
D. terminators
E. coinducers

25. T or F - The regulation of the maltose operon and catabolite repression of the lactose operon are examples of positive control.

26. The repression of the lactose operon by the presence of glucose is mediated through ________.
A. elevated level of cyclic AMP in the cell
B. low levels of cyclic AMP (cAMP) in the cell
C. a lac repressor /glucose complex binding to the lac operator
D. glucose binding to the lac operator
E. None of the above.

27. Genes for utilizing maltose are scattered throughout the chromosome of Escherichia coli and are under control of the same regulatory protein. The maltose-utilizing genes are an example of a _____.
A. an operon
B. regulon
C. stimulon
D. modulon
E. none of the above

28. Which of the following statements is False about cells in the early part of the second phase of diauxic growth in a glucose/lactose based medium?
A. The lac repressor is bound to the inducer and cannot bind to the operator region.
B. The levels of cyclic AMP are elevated relative to the first phase of growth.
C. The lac operon is induced.
D. cAMP/CAP is bound to the CAP binding site.
E. All of the above statements are true.

29. The two component regulatory system involved in signal transduction are composed of ______________.
A. repressors and corepressors
B. activators and inactivators
C. sensors and response regulators
D. transducers and corepressors
E. None of the above.

30. Attenuation, an effective means of regulating amino acid biosynthetic genes in bacteria, requires _________.
A. a repressor
B. a activator protein
C. coupling of transcription and translation
D. an inducer
E. feedback inhibition

31. A strain of Escherichia coli that requires an amino acid for growth is called a ___.
A. autotroph
B. lysogen
C. prototype
D. prototroph
E. auxotroph

32. T or F - A point mutation (i.e., a base pair substitution) in the third position of a codon always lead to missense mutations.

33. You obtained a mutant strain of E.coli through chemical mutagenesis using 5- bromouracil. Subsequently you found that the strain had reverted back to the wildtype phenotype in high frequency. What type of mutant did you obtain from chemical mutagenesis?
A. base-pair substitution
B. microdeletion
C. microinsertion
D. pyrimidine dimer
E. suppressor mutant

34. Ultraviolet light is used in germicidal lamps to kill bacteria. Ultraviolet light in the 260 nm region causes __________, which may be lethal, to form in DNA.
A. microdeletions
B. point mutations
C. pyrimidine dimers (e.g., thymine dimers)
D. microinsertions
E. None of the above.

35. The ______ is used to determine if a chemical is mutagenic and potentially carcinogenic.
A. complementation test
B. Ames test
C. transposon test
D. penicillin-test
E. fixation test

36 - 40. Match each term with the appropriate statement (A-E) about it.
36. Transformation A. F-factor is integrated in chromosome
B. Recipient cell

37. Transduction C. Absorbtion of DNA from the environment
D. Bacteriophage-mediated DNA transfer cell

38. Hfr E. F-factor separate from chromosome

39. F⁺

40. F^-

Each of the following is worth 10 pts. Write your answers on the sheet of paper provided.
41. A culture of bacteria with a generation time (g) of 0.2 will grow from 3 x 10³ to 10¹¹ cells in how many hours?

42. Draw a replication fork and place and/or label the following clearly:
* 5´ and 3´ end of both parent strands of DNA
* leading strand with 5´ and 3´ end labelled
* DNA polymerase III
* helicase
* single-stranded binding proteins
* primase
* lagging strand
* using arrows, indicate the direction of DNA synthesis of both strands.

43. Copy the below diagram to your paper twice for question 43a and 43ba) Draw the interaction of repressor and the lac operon in the absence of lactose. Be sure to include the repressor, promoter, structural genes, operator, RNA polymerase and inducer. Also indicate whether the operon is expressed or not.
b) Draw the interaction of the repressor and the lac operon in the presence of lactose. Be sure to include the repressor, promoter, structural genes, operator, RNA polymerase and inducer. Also indicate wherther the operon is expressed or not.

44. a) Draw a mating between an F⁺ and an F^- Escherichia coli cell. Indicate the outcome of this mating.
b) Draw a mating between an Hfr and an F^- E. coli cell. Indicate the outcome of this mating.

Microbiology 2124
Exam 3
Nov. 23, 1998
David Demezas

General Instructions: Answer multiple choice questions on the test sheet. Answer other questions in the space provided on the test sheet. Be sure that you answer the question in complete sentences. Write your name on all pages of the test.
Multiple Choice (2.5 pts each). Choose the most correct answer and mark the corresponding letter on the blank provided to the left of the question.

1. Which gene is used routinely to determine the phylogenetic relationship among bacteria?
A. beta-galactosidase
B. 5S rRNA
C. tryptophan tRNA
D. 16S rRNA
E. DNA polymerase

2. Which of the following do not include anoxic phototrophic species of bacteria?
A. Green sulfur bacteria
B. Green non sulfur bacteria
C. Purple non sulfur bacteria
D. Purple sulfur bacteria
E. Cyanobacteria

3. Which of the following types microorganisms would be enriched in a basal salts medium supplemented with bicarbonate, vitamin B12, sodium sulfide (0.1% w/v) and a weak light source.
A. Purple non sulfur bacteria
B. Cyanobacteria
C. Green sulfur bacteria only
D. Purple sulfur bacteria only
E. Purple sulfur and green sulfur bacteria

4. The site of nitrogen fixation in most cyanobacteria is in the _____.
A. akinete
B. heterocyst
C. hormogonium
D. vegetative cell
E. cyanophycin

5. True or false: Chemolithotrophs are predominantly aerobic microorganisms that generate ATP by the oxidation of reduced inorganic compounds.

6. Nitrifiers carry out which of the following ecological functions in soils?
A. Reduction of ammonia to nitrate
B. Oxidation of methane to methanol
C. Reduction of sulfate to sulfide
D. Oxidation of ammonia to nitrate
E. Oxidation of hydrogen gas to protons

7. Sulfate-reducing bacteria are widely distributed in nature. Which of the following would not be proper for enrichment medium used for their isolation?
A. a lactate-sulfate medium
B. ascorbate or thioglycolate
C. ferrous iron
D. incubation under aerobic conditions

8. Which of the following is a Gram-positive, endospore-forming microorganism that produces an insecticidal protein?
A. Pseudomonas sp.
B. Azotobacter sp.
C. Bacillus sp.
D. Chromobacterium sp.
E. Klebsiella sp.

9. Escherichia, Enterobacter, Shigella, and Salmonella are all members of the group of bacteria called _______.
A. colonic bacteria
B. stomach bacteria
C. enteric bacteria
D. hemmorhagic bacteria
E. planktonic bacteria

10. Species of Halobacterium may use which of the following for energy?
A. light-driven ATP production
B. Fermentation
C. Oxidation of organic compounds
D. only A and B
E. A, B and C are correct.

11. _____________, a membrane-associated protein, plays an integral role in the generation of a proton motive force to drive ATP synthesis in Halobacterium.
A. carotenoids
B. bacteriorhodopsin
C. ATPase
D. cytochrome oxidase
E. catalase

12. True or False? Methanogens are obligate aerobes.

13. All hyperthermophilic Archaea have a temperature optimum _______.
A. between 50 and 80 ^oC
B. above 80 ^oC
C. below 50 ^oC

14. Hyperthermophiles produce large amounts of ______ as an adaptation to their extreme environment.
A. 2,3 diphosphoglycerate
B. water
C. glucose
D. pyruvate
E. citrate

15-18 Matching. Match the correct description with the genus of bacteria.

15. Methanopyrus

16. Thermoplasma

17. Archaeoglobus

18. Pyrodictium

19. Which type(s) of metabolism is/are found in the algae?
A. phototrophy
B. chemoorganotrophy
C. photoheterotrophy
D. only A and C
E. A, B, and C

20. Which type(s) of metabolism is/are found in the fungi?
A. photoautotrophy
B. chemolithotrophy
C. chemoorganotrophy
D. photoheterotrophy
E. A, C, and D

21. Which of the following fungi does not produce spores?
A. Deuteromycetes
B. Oomycetes
C. Zygomycetes
D. Basidiomycetes
E. Ascomycetes

22. True or False? Yeasts reproduce by budding.

23. Which of the following is a signal for slime molds to aggregate?
A. cAMP
B. riboflavin
C. ATP
D. glucose
E. 6-phosphofructose

24. The usual mode for protozoa to obtain food is by _____.
A. autotrophy
B. phototrophy
C. phagotrophy
D. lithotrophy
E. None of the above

25. Which of the following groups of protozoa includes the foraminiferas that compose the White Cliffs of Dover?
A. Mastigophora
B. Sarcodina
C. Ciliphora
D. Sporozoa

26. Which of the following protozoan groups may cause infectious disease in humans?
A. Mastigophora
B. Sarcodina
C. Ciliphora
D. Sporozoa
E. All of the above

27. Which of the following is an asexual spore?
A. basidiospore
B. ascospore
C. conidia
D. oospore
E. zygospore

28. Bacteriophage can be enumerated using the __________.
A. restriction endonucleases
B. coliform alert
C. Ames test
D. plaque assay
E. None of the above

29. Bacteria use _________ to cleave and destroy incoming DNA such as viral DNA.
A. polymerases
B. restriction endonucleases
C. ligases
D. primases
E. telomerases

30. Retroviruses are RNA viruses that contain _____________ to synthesize DNA from their RNA upon infection of the host cell.
A. DNA polymerase
B. RNA polymerase
C. reverse transcriptase
D. Taq polymerase
E. none of the above

31. Which of the following viruses is/are a male-specific virus(es) that attach to the F-pili?
A. MS2
B. lambda
C. M13
D. lambda and M13
E. MS2 and M13

32. Negative strand RNA viruses must synthesize a positive strand RNA that is translated into proteins. What enzyme do these viruses use to synthesize a positive strand RNA?
A. DNA dependent DNA polymerase
B. RNA dependent DNA polymerase
C. RNA dependent RNA polymerase
D. DNA dependent RNA polymerase

33. The temperate virus lambda DNA may integrate into the host bacterium's chromosome. Lambda is now referred to as a _________.
A. lysogen
B. prophage
C. plasmid
D. cosmid
E. transposon

34. Identify the virus game! "Other bacteriophage might "think" me weird because of my unusual shape since I am linear and skinny, although my DNA is circular. I am not very versatile with regards to hosts- I associate only with male E. coli. I am rather gentle to my host since I do not induce lysis, and therefore do not form obvious plaques. Gene jockeys like to us me as a producer of cloned single-stranded DNA since all of my rather small genome is not required for my survival and my host's factory remains intact. WHO AM I?"
A. T4 Bacteriophage
B. T7 Bacteriophage
C. Phi Chi 174
D. M13
E. lambda

35. Which two viruses use the rolling circle mechanism during replication?
A. phi chi 174 and lambda
B. M13 and MS2
C. T7 and MS2
D. phi chi 174 and T7
E. M13 and T7

36. Which two proteins play a central role in deciding whether lambda phage enters the lysogenic state or the lytic cycle?
A. cro and CI (lambda repressor)
B. cro and N
C. CII and N
D. CII and CIII
E. N and CIII

37. True or False? Catabolite repression plays a role in the decision making process for lambda to enter the lytic cycle or lysogenic state.

38. True or False? Antibiotics are secondary metabolites.

39. Vitamin B12 is made exclusively by microorganisms. Commercially B12 is synthesized by _________.
A. Bacillus species
B. Propionibacterium species
C. Streptomyces species
D. Ashbya species
E. Rhizopus species

40. Lambda cohesive (cos) site cloned into a plasmid results in a _______.
A. new bacteriophage
B. cosmid
C. phagemid
D. yeast artificial chromosome
E. none of the above.

41. (10 pts) Complete the following table.

Nutritional types	source of energy	source of carbon	Example
Photoautotroph	light	CO2	cyanobacteria
photoheterotrophs	light	organic compounds	Purple Non-sulfur bacteria
chemolithotroph	reduced inorganic compounds	CO2	nitrifiers
chemoorganotrophs	organic compounds	organic compounds	E. coli

42. (10 pts) Most hyperthermophiles are obligate anaerobes; some species of the hyperthermophile Acidianus are facultative aerobes. Acidianus uses elemental sulfur when growing aerobically and anaerobically. Briefly explain the role of elemental sulfur when Acidianus is growing a) aerobically and b) anaerobically.

43. (10 pts) Draw a one-step growth curve of viruses. Be sure to label both the x and y axis correctly. In your drawing clearly indicate the latent and maturation periods.