Microbiology 2124
Final Exam
May 7, 1999
David Demezas

General Instructions: Choose the most correct answer and mark the corresponding letter on your scantron answer sheet. The key will be posted by my door and on the web later today, so you may wish to record your answers on your test to grade it.

1. The criteria used to relate a specific microbe to a specific infectious disease (the germ theory of disease) were established by ________ in the last century.
A. Pasteur
B. Petri
C. Hooke
D. Koch
E. Leeuwenhoek

2. Which of the following domains do not have a membrane bound nucleus?
A. Archaea
B. Bacteria
C. Eukarya
D. Both A and B
E. Both B and C

3. Which of the following is not a feature of the plasma membrane?
A. It is composed of phospholipids arranged in a lipid bilayer.
B. Integral proteins are embedded in the plasma membrane.
C. The peptidoglycan layer is an integral part of the plasma membrane.
D. It is selectively permeable.
E. It is a fluid structure.

4. Which of the following is not found in the peptidoglycan layer of a bacterium?
A. N-acetyl glucosamine
B. N-acetyl muramic acid
C. pyruvate
D. amino acids
E. All of the above are found in the peptidoglycan layer.

5. Which of the following is not a general feature of active transport?
A. Requires a carrier protein
B. Requires a form of energy
C. Can move molecules against a concentration gradient
D. All of the above are characteristic of active transport

6. The pathway that yields pyruvate from glucose is called ________.
A. Krebs cycle
B. glycolysis
C. gluconeogenesis
D. Tricarboxylic acid cycle
E. Calvin cycle

7. The majority of the ATP generated from aerobic respiration results directly from ______.
A. substrate level phosphorylation
B. the oxidation of NADH + H⁺
C. oxidative phosphorylation
D. the TCA cycle (syn. Krebs or citric acid cycle)
E. glycolysis

8. Which of the following statements about the proton motive force is false?
A. It is composed of a pH gradient and electrochemical potential.
B. The proton motive force is generated as electrons move down an electron transport chain and protons are extruded out of the cell.
C. The cytoplasm of the cell becomes more acidic.
D. The proton motive force can be used to drive ATP synthesis using ATP synthase.
E. All of the above statements are true.

9. The flow of electrons down the electron transport chain generates a proton motive force yielding ATP in all of the following except ________.
A. aerobic respiring bacteria
B. chemolithotrophs
C. anoxygenic phototrophs
D. fermentative bacteria and yeasts
E. oxygenic phototrophs

10. Which of the following statements about facultative aerobes is correct?
A. They can grow in the presence of a suitable electron acceptor, e.g., nitrate, in an anaerobic environment.
B. They are extremely sensitive to even the smallest amounts of oxygen.
C. They require oxygen for growth.
D. They use only substrate level phosphorylation to make ATP.
E. They are strictly fermentative organisms.

11. The above figure best illustrates the cell wall of _________.
A. a Gram negative bacterium
B. a protozoa
C. fungi
D. an Archaean cell
E. a Gram positive bacterium

12. The rigidity and shape of a bacterium is due to the _______.
A. cell membrane
B. peptidoglycan layer
C. lipopolysaccharide
D. teichoic acid layer
E. none of the above

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

14. Anoxygenic phototrophic bacteria generate ATP using _________ .
A. non cyclic photophosphorylation
B. oxidative phosphorylation
C. cyclic photophosphorylation
D. substrate level photophosphorylation
E. substrate level phosphorylation

15. ________ use light as an energy source and organic compounds as their carbon source.
A. Photoautotrophs
B. Chemolithotrophs
C. Photoheterotrophs
D. Chemoorganotrophs
E. Chemoautotrophs

16. Components of the electron transport chain is located in the ________.
A. cytoplasm of the cell
B. peptidoglycan layer
C. lipopolysaccharide layer
D. periplasmic space
E. plasma membrane

17. The first person to see microorganisms using crude, hand-crafted microscopes was ____________.
A. Hooke
B. van Leeuwenhoek
C. Winogradsky
D. Pasteur
E. Koch

18. Autotrophic CO₂ fixation to organic matter in autotrophic bacteria is a function of the _______.
A. Krebs cycle
B. glycolytic pathway
C. Calvin cycle
D. electron transport chain
E. fermentative pathway

19. True (A) or False (B): Sulfate respiration occurs in aerobic environments (i.e., oxic environments)

20. True (A) or False (B): A simple majority (i.e., >51%) of all species of microorganisms cause disease.

21. The time required for the formation of two cells from one cell is called _____.
A. the generation time
B. the doubling time
C. the growth rate
D. the dilution rate
E. A and B

22. During which phase of the growth curve might secondary metabolites (e.g., toxic compounds) be produced and growth occur without a net increase in the viable count?
A. lag
B. exponential
C. stationary
D. death
E. log

23. Penicillin inhibits _______
A. bacterial cell wall synthesis
B. bacterial protein synthesis
C. fungal cell wall synthesis
D. DNA replication
E. glycolysis

24. The decimal reduction time is ______.
A. the time required to kill all cells in a population at a given temperature
B. the time required to kill all cells in an autoclave
C. the time required to reduce the population of bacteria tenfold at a given temperature
D. the time required for a population to increase by tenfold
E. None of the above is correct.

25. Which of the following statements about DNA is incorrect?
A. DNA is composed of the four nucleotides adenine, guanine, cytosine, and thymine.
B. DNA is a double helix composed of two polynucleotides held together by hydrogen bonds.
C. The two polynucleotides have an antiparallel orientation.
D. The nucleotides are joined together by sulfhydryl bonds.
E. The polynucleotides have a sugar phosphate backbone.

26. According to the "Central dogma of molecular biology", 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

27 The lac repressor protein regulates the lactose operon by ________.
A. repressing the activity of pre-existing enzymes
B. blocking transcription of protein from a mRNA
C. blocking DNA synthesis during transcription
D. blocking transcription of the operon by RNA polymerase
E. None of the above.

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

29. Consider a mutation which occurs in which the change is from UAC to UAU, where both triplets code for the amino acid tyrosine. This is an example of a _____.
A. silent mutation
B. nonsense mutation
C. missense mutation
D. a point mutation
E. A and D

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

31. Species of bacteria that spoil foods in a refrigerator are most likely _________.
A. mesophiles
B. barophiles
C. thermophiles
D. acidophiles
E. psychrophiles

32. Given a population of bacteria with an initial population of 5 x 10⁵ cfu/ml and a population of 1.28 x 10⁸ cfu/ml after 1 hour. How many generations has this culture gone through?
A. 1
B. 2
C. 4
D. 6
E. 8

33. Compounds that are structurally similar to required growth factors and inhibit the growth of microorganisms are called ______.
A. growth factor analogs
B. vitamins
C. coenzymes
D. cofactors
E. amino acids

34. True (A) or False(B): Antiseptics are chemical agents that inhibit or kill microorganisms and are sufficiently non-toxic to be used on living tissue.

35. ______ are the site of polypeptide synthesis. A. Ribozymes
B. RNA polymerases
C. Ribosomes
D. DNA polymerases
E. Nitrogenases

36. Which of the following is a characteristic of the lagging strand synthesis of DNA?
A. Continuous synthesis of the lagging strand towards the replication fork.
B. Synthesis of the lagging strand with an RNA template strand.
C. The lagging strand is synthesized by RNA polymerase.
D. Multiple RNA primers are needed for the lagging strand’s synthesis.
E. All of the above are characteristic of lagging strand synthesis.

37. True (A) or False (B): A tRNA can carry more than one type of amino acid to the growing polypeptide.

38. An operon where a regulator protein promotes the binding of RNA polymerase, thus increasing the amount of mRNA transcripts is ________.
A. negatively controlled
B. repressed
C. an example of attenuatio
D. positively controlled
E. catabolite repressed

39. A(n) _______ is a genetic element that is capable of moving from on segment of the chromosome to another and may code for antibiotic resistance genes.
A. plasmid
B. transposon
C. insertion element
D. mu
E. gamete

40. True (A) or False (B): An Hfr strain of E. coli mated with an F^-(minus) strain always results in the conversion of the F^-(minus) strain into an Hfr.

41. Which of the following species of phototrophic bacteria has two photosystems analogous to higher plants?
A. Green sulfur bacteria
B. sulfate reducing bacteria
C. Purple non sulfur bacteria
D. Purple sulfur bacteria
E. Cyanobacteria

42. Which of the following characteristics is common to both pseudomonads and Escherichia coli?
A. They both produce endospores.
B. They are both Gram negative rods.
C. They are both enteric bacteria.
D. They both are strict anaerobes.
E. All of the above are true about pseudomonads and Escherichia coli.

43. Which of the following characteristics unifies the phylogenetic group Crenarchaeota?
A. extreme halophiles
B. hyperthermophily
C. methanotrophy
D. chemolithotrophy
E. None of the above.

44. True (A) or False (B): Methane is generated by methanogens when they use carbon dioxide as a terminal electron acceptor in anaerobic respiration.

45. Which of the following human infectious diseases has been eradicated?
A. Smallpox
B. AIDS
C. Measles
D. Cholera
E. Flu

46. Which of the following statements about virus replication is false?
A. Virus replication involves de novo synthesis of viral proteins.
B. Viruses are obligate intracellular parasites.
C. Viruses reproduce by binary fission.
D. A and C
E. None of the above statements are false.

47. Which of the following are phototrophs?
A. algae
B. mushrooms
C. slime molds
D. protozoa
E. yeast

48. Which of the following statements about fungi is false?
A. They are heterotrophs.
B. Their cell wall is composed of chitin.
C. They do not have chlorophyll.
D. They do not contain a membrane bound nucleus.
E. They are decomposers.

49. The production of secondary metabolites occurs at or near the onset of which microbial growth phase?
A. Lag
B. Log
C. Exponential
D. Stationary
E. Death

50. Important industrial products produced by microorganisms include ____.
A. the cells themselves
B. primary metabolites
C. enzymes
D. secondary metabolites
E. all of the above.

51. A recognized resource book on prokaryote taxonomy is ________.
A. the American Type Culture Collection
B. Bergey’s Manual of Determinative Bacteriology
C. the American Society for Microbiology
D. your text book
E. none of the above

52. 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

53. True (A) or False (B): Volcanic habitats have been the source of some of the most interesting hyperthermophiles, some of which grow at 100^oC.

54. Which of the following is not an adaptation of hyperthermophiles to high temperatures?
A. Synthesis of 2,3 diphosphoglycerate
B. Synthesis of DNA binding proteins
C. Modification in the primary sequence of polypeptides (e.g., proteins)
D. Synthesis of molecular chaperonins
E. All of the above are adaptations of hyperthermophiles to high temperatures.

55. During what stage of viral replication are the number of infectious virus particles (plaque-forming units) at their lowest?
A. latent period
B. penetration
C. maturation
D. release
E. attachment

56. True (A) or False (B): Viruses have been isolated from animals, plants, fungi but not bacteria.

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

58. 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

59. Which of the following is(are) not a secondary metabolite?
A. antibiotics
B. ethanol
C. vitamins
D. amino acids
E. B, C, and D.

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

61. Some pathogenic species of bacteria produce ____ to extract iron from iron carrying molecules like lactoferrin. A. transferrin
B. siderophores
C. fimbriae
D. hyaluronidase
E. streptokinase

62. True (A) or False (B): Tissue and host specific adherence is one of the initial interactions which leads to an infection of a host by a pathogen.

63. Which of the following causes lysis of redblood cells?
A. streptokinase
B. coagulase
C. hemolysin
D. collagenase
E. None of the above.

64. Endotoxins are usually associated with what type of microorganism?
A. Gram positive
B. Gram negative
C. protozoa
D. fungi
E. algae

65. Enterotoxin-producing strains of E. coli cause which of the following symptoms?
A. flaccid paralysis
B. systemic shock
C. diarrhea
D. rash
E. None of the above.

66. Which of the following is not a characteristic of an exotoxin?
A. heat labile (protein)
B. highly toxic
C. produces a fever
D. highly immunogenic
E. specific in their mode of action (e.g., neurotoxin)

67. True (A) or False (B): Only lysogenic strains of Corynebacterium diptheriae produce the diptheria exotoxin

68. Which of the following microorganisms may be a part of our normal skin microflora and is occassionally associated with food poisoning?
A. Clostridium perfringens
B. Vibrio cholerae
C. Pseudomonas aeruginosa
D. Staphylococcus aureus
E. Bacillus cereus

69. Which of the following is not an exotoxin?
A. the cholera toxin
B. the tetanus toxin
C. the diphtheria toxin
D. the LPS of Salmonella
E. the enterotoxins

70. True (A) or False (B): Clostridium tetani is a strict anaerobic soil organism that produces a neurotoxin that can lead to death.

71. A disease that is constantly present at a low incidence, in a population is called a(n) _________ disease.
A. pandemic
B. epidemic
C. endemic
D. pandia
E. pangeae

72. Which of the following are resevoirs of diseases?
A. animals
B. soil
C. water
D. man
E. All of the above.

73. True (A) or False (B): Typhoid Mary was an example of a chronic carrier of a disease. She may have been apparently healthy, but still harbored viable Salmonella typhi and spread it while she was a cook in various eating establishments.

74. Lyme disease is caused by Borrelia burgdorferi and is transmitted by infected ticks. This is an example of _______.
A. a sexually transmitted disease
B. a direct contact disease
C. a vector-borne disease
D. None of the above.

75. True (A) or False (B): A disease that primarily occurs in animals but can be transmitted to humans is referred to as a zoonosis.

76. Urinary tract infections caused by E. coli and P. aeruginosa may be acquired in hospitals. These are examples of _________.
A. fomites
B. nosocomial infections
C. vectors
D. zoonosis
E. None of the above.

77. True (A) or False (B): Hospital strains of Pseudomonas aeruginosa are frequently resistant to numerous antibiotics due to either plasmids or transposons.

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

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. Cholera, a water-borne pathogen, has a ________disease pattern, where there is a sharp rise in the incidence of the disease and a relatively rapid decline.
A. host to host epidemic
B. common-source epidemic
C. vector-borne endemic
D. pandemic
E. None of the above.