Microbiology 2124: Exam 2
October 10, 2001
Dr. Babu Z. Fathepure

General Instructions:
Write your name clearly on all pages.
Choose the most correct answer and mark the corresponding letter on your scantron sheet.
Answer the supplement questions on page 7. The supplement-questions page should be detached and returned to the instructor for grading.
The multiple choice questions are worth 3.33 points each.

Multiple Choice Questions:
1. Which of the following processes does not generate ATP?
a) photophosphorylation
b). the Calvin-Bensen cycle
c). oxidative phophorylation
d). substrate-level phosphorylation

2. Which substance in the following fermentative reaction serves as an electron acceptor?

CH3-CHO + NADH + H+

CH3-CH2OH + NAD+

a). acetaldehyde
b). NADH
c). ethanol
d). NAD⁺

3. Most chemoautotrophs generally use substrates such as
a). glucose
b). carbon dioxide
c). oxygen
d). sunlight

4. If there are 10³ cells/ml at the middle of log phase, and the generation time of the cells is 30 minutes, how many cells will there be after 2 hours?
a). 2 x 10³
b). 4 x 10³
c). 8 x 10³
d). 1.6 x 10⁴
Solution à N = N₀ x (2)ⁿ n= t/g
N = 1,000 x 16 n = 120/30
N = 16,000 = 1.6 x 10⁴ n = 4

5. In which of the following four phases of growth curve, are microbes most sensitive to penicillin?
a). phase 1
b). phase 2
c). phase 3
d). phase 4

6. Nutrient broth is an example of a…
a). defined medium
b). complex medium
c). selective medium
d). differential medium

Q. Below is a typical growth curve of bacteria with various stages numbered 1-4. Please answer question 7 and 8 using the following figure.

3

7. Which stage shows a phase where the number of cells dying equals the number of cells dividing?
a). stage 1
b). stage 2
c). stage 3
d). Stage 4

8. Which stages of the graph illustrate a logarithmic change in cell number?
a). 1 and 3
b). 2 and 4
c). 2 and 3
d). 1 and 4

9. Which of the following types of media would not be used to culture aerobic bacteria?
a). differential media
b). enrichment medium
c). reducing media
d). complex media

10. Which of the following is not used to determine metabolic activity?
a). acid production from fermentation
b). CO₂ production from the Krebs cycle
c). oxygen consumption
d). turbidity measurement

11. All of the following are direct methods to measure microbial growth except:
a). microscopic count
b). standard plate count
c). filtration
d). metabolic acivity

12. Which group of microorganisms is most likely to spoil a freshwater trout preserved with salt?
a). psychrophiles
b). halophiles
c). thermophiles
d). anaerobes

13. The number of colonies obtained in a plate count does not depend on
a). inoculum size
b). size of the colonies
c). type of culture medium
d). length of incubation

14. Which of the following forms of oxygen are generally toxic to living organisms?
a). superoxide anion
b). hydrogen peroxide
c). hydroxyl radical
d). all of the above

15. Which of the following methods is used to sterilize heat-labile solutions?
a). dry heat
b). autoclave
c). filtration
d). pasteurization

16. Agents that kill bacteria are called
a). inhibitory
b). bactericidal
c). bacteriostatic
d). all of the above

17. The time required for a 10-fold reduction in population density at a given temperature is called the
a). thermal death time
b). decimal reduction time
c). mean strerilization time
d). none of the above

18. The antimicrobial activity of chlorine is due to which of the following?
a). the formation of hypochlorous acid
b). the formation of hydrochloric acid
c). the formation of trihalomethanes
d). the formation of chloride ion

19. Iodophors differ from iodine in that iodophors
a). are combined with an organic molecule for slow release
b). are less irritating
c). are long lasting
d). all of the above

20. Which of the following substances is the least effective antimicrobial agent?
a). soap
b). cationic detergents
c). phenolics
d). alcohol

21. Which concentration of ethyl alcohol is the most bacteriocidal?
a). 100%
b). 70 %
c). 30 %
d). 50 %

22. In the flowing figure, antimicrobial agents were added to exponentially growing cultures at the time shown by an arrow. Which of the lines indicates the addition of a bacteriocidal compound?

23. Which of the following enzymes converts hydrogen peroxide to oxygen and water?
a). oxidase
b). carboxylase
c). catalase
d). polymerase

24. If you determined that the DNA of a species of bacteria was 27% cytosine, you would correctly predict that there is ______% thymine in the DNA.
a). 27%
b) 23%
c). 73%
d). 0%

25. Which of the following pairs is mismatched?
a). DNA polymerase — makes a molecule of DNA from a DNA template
b). RNA polymerase — makes a molecule of RNA from an RNA template
c). RNA polymerase — makes a molecule of RNA in 5’à3’ direction
d). DNA polymerase — makes a molecule of DNA in 5’à3’ direction

26. Which of the following is not a product of transcription?
a). a new strand of DNA
b). rRNA
c). tRNA
d). mRNA

27. A gene is best defined as
a). a segment of DNA
b). three nucleotide that code for an amino acid
c). a sequence of nucleotide in DNA that code for a functional product
d). a sequence of nucleotide in RNA that code for a functional product.

Supplemental Questions
Microbiology 2124: Exam 2
October 10, 2001

1. Fill in the following table with the carbon source and energy source of each type of organism (3 points).

2. There is only one correct answer to each question in right panel; please write the best answer to the question in the left panel (7 points)

3.

Microbiology 2124
Exam 3
Nov. 22, 1999
David Demezas

General Instructions: Answer multiple choice questions on your scantron sheet. Choose the single most correct answer and mark the corresponding letter on your scantron sheet.

1. The five kingdom system of biological classification consists of all of the following except _______.
a. Animalia
b. Plantae
c. Protista
d. Monera (Procaryotae)
e. Protozoa

2. Which of the following is the correct taxonomic hierarchy from the most general to the more specific taxon?
a. domain, kingdom, phylum, class, order, family, genus, species
b. kingdom, domain, phylum, class, family, order, genus, species
c. domain, kingdom, class, phylum, family, order, genus, species
d. kingdom, domain, phylum, class, order, family, genus, species
e. kingdom, domain, class, phylum, family, order, genus, species

3. A major difference between the procaryotes Archaea and Eubacteria is _______.
a. the absence of ribosomes in Archaea
b. the presence of a nucleus in Archaea
c. the absence of a peptidoglycan layer in Archaea
d. the presence of mitochondria in Eubacteria
e. the presence of a nucleus in Eubacteria

4. The evolutionary history of a group of organisms is known as their _________.
a. taxonomy
b. classification
c. identification
d. phylogeny
e. none of the above

5. The genera Bacillus and Lactobacillus are gram-negative rods and are not in the same family. This indicates that which one of the following is not sufficient to assign an organism to a taxon? a. Biochemical characteristics
b. DNA sequencing
c. DNA:DNA hybridization analysis
d. Morphological characteristics
e. Fatty acid profiles

6. The "bible" of bacterial taxonomy is ______.
a. the American Society for Microbiology
b. the National Type Culture Collection
c. the American Type Culture Collection
d. Bergey's Manual of Systematic Bacteriology
e. the Journal of Bacteriology

7. Which of the following is(are) correctly typed/written?
a. Es. Coli
b. Esherichia coli
c. escherichia coli
d. E. coli
e. b and d

8. True (A) or False (B): The results of 95 biochemical tests performed on 100 strains of the same species of bacteria (e.g., Staphylococcus aureus) must be identical for all 100 strains.

9. Strains of bacteria that are susceptible to a specific bacteriophage ________.
a. produce antibodies against the bacteriophage
b. produce plaques
c. agglutinate in immunoassays
d. produce restriction enzymes to prevent infection by the bacteriophage
e. none of the above are true.

10. Western blotting detects specific bacterial proteins by ________.
a. their reactions with specific antibodies
b. their hybridization with a labeled DNA probe
c. biochemical tests
d. their reactions with specific dyes (e.g., crystal violet)
e. their reactions with specific bacteriophages

11. Southern blotting detects specific sequences of DNA by __________.
a. DNA:DNA hybridization
b. RNA:DNA hybridization
c. DNA sequencing
d. antigen:antibody interactions
e. None of the above.

12 Identification of unknown bacteria using fatty acid profiles is based on which of the following macromolecule?
a. Phospholipids
b. DNA
c. Ribosomes
d. carbohydrates
e. the peptidoglycan layer

13. True (A) or False (B): Two unknown bacteria with the same G+C% must belong to the same species of bacteria.

14. 16S ribosomal RNA sequencing is used to determine the phylogenetic relationships between bacteria for all of the following reasons except _________.
a. All cells contain rRNA.
b. Closely related species have fewer differences than distantly related species
c. rRNA genes are highly conserved compared to other DNA sequences.
d. rRNA doesn't require culturing the organism.
e. Only Eubacteria have 16S rRNA genes.

15. A bacterial species is defined as _____________.
a. a population of bacteria that can sexually reproduce and produce viable offspring
b. a group of bacteria isolated from the same habitat (e.g., a puddle of water)
c. a population of bacteria with similar characteristics
d. a group of bacteria that are sensitive to a defined group of antibiotics
e. a population of bacteria with the same morphology

16. True (A) or False (B). Nosocomial infections are infections acquired in a hospital.

17. Gram negative bacteria may also be referred to as _______.
a. Gracilicutes
b. Firmicutes
c. Tenericutes
d. Archaea

18 Bacteria with axial filaments and were first described by Leeuwenhoek are classified as _____.
a. Streptococci
b. Staphylococci
c. Spirochetes
d. Pseudomonads

19. _________ is a gram-negative helical bacterium that has been implicated as a causative agent of ulcers.
a. Streptococcus pneumoniae
b. Rhizobium meliloti
c. Helicobacter pylori
d. Pseudomonas aeruginosa
e. Staphylococcus aureus

20. Members of the family Enterobacteriaceae include all of the following except ________.
a. Escherichia
b. Salmonella
c. Klebsiella
d. Shigella
e. Bacteroides

21. Which of the following species of bacteria plays a role in the production of yogurt?
a. Lactobacillus
b. Escherichia
c. Azotobacter
d. Listeria
e. Mycobacteria

22. Which of the following is a gram-positive, endospore forming, rod that produces an insecticidal protein?
a. Corynebacteria
b. Bacillus
c. Clostridium
d. Staphylococcus
e. Lactobacillus

23. Which of the following uses sulfate or elemental sulfur as a terminal electron acceptor for anaerobic respiration?
a. Rickettsia
b. Mycoplasma
c. Desulfovibrio
d. Escherichia
e. Bacillus

24. Which of the following does not form a cell wall?
a. Mycoplasma
b. Pseudomonas
c. Staphylococcus
d. Streptococcus
e. Escherichia

25. True (A) or False (B): Streptococcus pneumoniae occurs as diplococci.

26. Caulobacter are characterized by all of the following except _______.
a. Stalk
b. Swarming cells
c. Non-motile cells
d. Oligotrophic
e. All of the above are characteristics of Caulobacter.

27. Chemoautotrophic bacteria get their energy from ________ for anabolic metabolism.
a. the oxidation of organic compounds
b. the sun
c. the reduction of oxidized compounds
d. the oxidation of reduced compounds
e. None of the above.

28. Which of the following phototrophic bacteria is oxygenic?
a. Purple sulfur bacteria
b. Green sulfur bacteria
c. Cyanobacteria
d. Purple nonsulfur bacteria
e. Green nonsulfur bacteria

29. The archaea _____ make methane from acetate or hydrogen gas and carbon dioxide.
a. Methanogens
b. Sulfate reducing bacteria
c. Nitrifiers
d. Denitrifiers
e. Enterics

30. True (A) or False (B): All cultured bacteria are too small to see with the unaided eye.

31. Most yeasts like Sacchromyces reproduce by ____.
a. budding
b. conidia
c. sporangia
d. basidia
e. None of the above

32. Eukaryotic, non-motile, non-photosynthetic organisms that absorb food from their environment are classified as _______.
a. Protozoa
b. Fungi
c. Algae
d. Lichens
e. bacteria

33. True (A) or False (B): Coenocytic hyphae contain no septa to divide hyphae into one nucleus cell-like units.

34. _____ are the "holding category" in which fungi are placed until sexual spores are observed.
a. Deuteromycota
b. Zygomycota
c. Ascomycota
d. Basidiomycota

35. Mushrooms belong to the phylum _________.
a. Deuteromycota
b. Zygomycota
c. Ascomycota
d. Basidiomycota

36. What nutritional types are found among algae?
a. Photoheterotroph
b. Chemolithotroph
c. Photoautotroph
d. Chemoautotroph
e. B and C

37. Agar used to solidify growth medium is derived from _____.
a. brown alga
b. red alga
c. green alga
d. cyanobacteria
e. None of the above

38. Red tides are due to the abundance of _________ in salt water.
a. Green algae
b. Diatoms
c. Dinoflagellates
d. Euglenoids
e. Brown algae

39. True (A) or False (B): Land plants may have evolved from brown alga.

40. Lichens are composed of a mutualistic association between _______.
a. Algae and bluegreen bacteria
b. Bacteria and algae
c. Fungi and algae
d. Fungi and heterotrophic bacteria
e. Protozoa and algae

41. _____ use pseudopods for motility
a. ciliates
b. mastigophora
c. amoebas
d. apicomplexa
e. microspora

42. Which of the following is not an obligate intracellular parasite?
a. Viruses
b. Chlamydia
c. Bacillus
d. Microspora
e. All of the above are obligate parasites.

For questions 43-45 complete the following:

43. _________ is the causative agent of malaria.
a. Trypanosoma
b. Giardia
c. Plasmodium

44. The definitive host were sexual reproduction occurs are _________
a. mosquitos
b. humans
c. Trypanosoma
d. Giardia

45. and the intermediate host were asexual reproduction occurs are _________.
a. Mosquitos
b. humans
c. Trypanosoma
d. Giardia
e. Escherichia

46. At what stage of the virus replication cycle does the virus bind to a host cell receptor?
a. Assembly
b. Penetration
c. Uncoating
d. Lysis
e. Attachment

47. Which of the following human viral infections has been eradicated?
a. Smallpox
b. AIDS
c. Measles
d. Common cold
e. Flu

48. Which of the following is not true?
a. Virus replication involves de novo synthesis of viral proteins.
b. Viruses are obligate intracellular parasites
c. Virus reproduces by binary fission
d. A and c
e. None of the above.

49. Of the following viruses, which one was the first virus recognized by a scientist?
a. Tobacco Mosaic virus
b. Human Immunodeficiency Virus
c. Herpes Virus
d. Smallpox Virus
e. None of the above

50. Viruses can be isolated from the following:
a. Animals only
b. Plants only
c. Fungi only
d. Bacteria only
e. All of the above.

For questions 51-55, if the statement is true, mark A or if the statement is false, mark B.
51. Bacteriophage lambda establishes lysogeny by inserting its DNA into the host cell's chromosome.
52. The genetic material of retroviruses is RNA.
53. Some viruses have a genome that consists of single-stranded DNA.
54. Some viruses can cause cancer.
55. Viruses are larger than bacteria.

For questions 56-60, match the genus with its description.

Microbiology 2124
Exam 2
Oct. 22, 1999
David Demezas

General Instructions: Answer multiple choice questions on your scantron 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 your scantron sheet.

1. The population size of bacteria increase by _________.
A. cloning
B. binary fission
C. replication
D. mitosis
E. meiosis

2. Given a population of bacteria with an initial population of 1 x 10⁶ cfu/ml and a population of 1 x 10⁹ cfu/ml after 1 hour. What is the most likely doubling time (generation time; g) of this culture?
A. 0.1 hours
B. 1 hour
C. 2 hours
D. 0.25 hours
E. 4 hours

3. Organisms that have adapted to live in the bodies of animals (e.g., you) are classified as ______.
A. psychrophile
B. thermophile
C. mesophile
D. extreme thermophile
E. psychrotroph

4. Which type of bacterium grows with or without oxygen in the presence of a suitable electron acceptor?
A. obligate anaerobe
B. obligate aerobe
C. facultative anaerobe
D. microaerophile
E. aerotolerant aerobe

5. As nutrients are depleted and waste products accumulate in a culture of bacteria, the growth of the population begins to slow and the culture enters the __________.
A. lag phase
B. log phase (syn. exponential phase)
C. stationary phase
D. Death phase
E. None of the above.

6. True (A) or False (B). A mid-log phase culture of bacteria growing in nutrient broth is inoculated into fresh, sterile nutrient broth. The new culture will not go through a lag phase as it grows.

7. Which of the following is used to determine the total number of cells (i.e., living and dead) in a culture?
A. spread plate counts
B. turbidity
C. microscopic counts
D. dry weight
E. pour plate counts

8. Which of the following enzymes converts hydrogen peroxide to oxygen and water?
A. oxidase
B. carboxylase
C. catalase
D. polymerase
E. ligase

9. Which of the following elements makes up the greatest percentage of bacteria by weight?
A. oxygen
B. phosphorous
C. nitrogen
D. iron
E. carbon

10. Mannitol salts agar with 7.5% salt and a pH indicator is an example of __________.
A. a selective medium only
B. a differential medium only
C. a selective and differential medium
D. none of the above.

11. True (A) or False (B). The chemical composition of complex media is well defined.

12. The time required to kill a suspension of bacteria held at a given temperature is referred to as _____.
A. decimal reduction time
B. thermal death time
C. thermal death point
D. none of the above.

13. True (A) or False (B). The autoclave operates at 15 lbs/ square inch pressure and 121 ^oC for 10 -15 minutes to sterilize moderately sized loads.

14. Ultra-violet lights are germicidal because ultra violet wavelengths of light cause ________, that are harmful to a bacterium, to form.
A. adenine dimers
B. guanine dimers
C. cytosine dimers
D. thymine dimers
E. all of the above

15. Food spoilage in the refrigerator is caused by _________.
A. mesophiles
B. psychrophiles
C. barophiles
D. thermophiles
E. psychrotrophs

16. True (A) or False (B). The volume of the medium bears no relationship to the time required for sterilization in the autoclave.

17. _______ are sufficiently non-toxic to be used on living tissue (e.g., your face).
A. Disinfectants
B. Antiseptics

18. Which of the following macromolecules is not a frequent target of chemical disinfectants?
A. plasma membrane
B. proteins
C. chromosome
D. All of the above are targets.
E. None of the above are targets.

19. The most widely accepted method for the disinfection of milk that allows it to retain its palatability is _______.
A. autoclaving
B. pasteurization
C. ultra violet light
D. none of the above
E. all of the above

20. True (A) or False (B). Non-ionizing radiation sterilizes materials by producing highly reactive hydroxyl radicals that react with and damage DNA and other macromolecules.

21. "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

22. DNA serves as a template for the synthesis of _______ by complementary base-pairing.
A. RNA and protein
B. DNA and RNA
C. RNA only
D. DNA and protein
E. DNA only

23. If you determined that the DNA of a species of bacteria was 27% cytosine, you would correctly predict that there is ______ thymine in the DNA.
A. 27%
B 23%
C. 73%
D. 0%

24. You have discovered a new drug that inhibits DNA ligase. This drug will prevent ________.
A. the formation of peptide bonds between adjacent nucleotides in a polynucleotide strand
B. the formation of phosphodiester bonds between adjacent amino acids in a polynucleotide strand
C. the formation of peptide bonds between adjacent amino acids in a polypeptide
D. the formation of phosphodiester bonds between adjacent nucleotides in a polynucleotide strand
E. hydrolysis of DNA into nucleotides

25. 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.

26. Which of the following statements about replication is False?
A. DNA polymerase adds incoming nucleotides to the 3 prime end of the growing polynucleotide strand.
B. DNA helicase and single stranded binding proteins are required to unwind the double helix of the DNA and hold the two strands of polynucleotides apart during replication.
C. Okazaki fragments make up the leading strand of DNA.
D. Replication begins at OriR and proceeds in both a clock-wise and counter clock-wise direction.
E. A single RNA primer is needed to begin synthesis on the leading strand of DNA.

27. How many nucleotides constitute a codon?
A. 1
B. 2
C. 3
D. 4
E. 6

28. True (A) or False (B). In enzyme repression and induction, the repressor is usually an allosteric protein.

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

30. The repression of the lactose operon by the presence of glucose is mediated through ________.
A. elevated level of cyclic AMP in the cell
B. depressed 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.

31. An operon is composed of _____________.
A. promoter, operator and structural gene(s)
B. promoter and operator only
C. operator and structural gene(s) only
D. promoter and structural gene(s)
E. none of the above

32. The function of the repressor of the lac operon is to ____________.
A. bind to the promoter in the absence of lactose
B. convert lactose to allolactose
C. bind to the promoter in the presence of lactose
D. bind to the operator in the presence of lactose
E. bind to the operator in the absence of lactose

33. A mutation of the base-pair substitution type that leads to premature termination of translation is called a(n) ____________.
A. silent mutation
B. missense mutation
C. non-sense mutation
D. deletion
E. insertion

34. Intercalating agents such as acrodine orange cause mutations by _________.
A. resembling normal nucleotides and causing basepair substitutions
B. modifying normal bases in the chromosome and causing basepair substitutions
C. inserting themselves between bases, therefore, spreading them apart and causing microdeletions
D. inhibiting DNA polymerase
E. by inhibiting RNA primase

35. True (A) or False (B). All point mutations in a structural gene lead to changes the amino acid sequence of the polypeptide.

36. 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

37. True (A) or False (B). Unlike mutations in eukaryotic organisms, all mutations in bacteria are inheritable.

Match the term with the correct definition from the right-hand column.

41. Given the following sequence of a gene, transcribe and translate it into a polypeptide. Be sure to show the product of transcription and translation.
5’ -GGATTCACATGTTTGTAGTCATTTAAATGGGCCGCGCAT-3’
Codon table
A) Transcription product:

B) Translation product:

42.

A) Diagram the interaction of the lac repressor and the lac operon in the absence of the inducer. This operon is or is not (circle one) expressed.

____p lacI_____p__lacZ___________lacY__________lacA________________

B) Diagram the interaction of the lac repressor and the lac operon in the presence of the inducer. This operon is or is not (circle one) expressed.

____p lacI_____p__lacZ___________lacY__________lacA________________