Microbiology 
Exam II, 1998                Name ______________ 

Part A Directions:Multiple choice. Circle the correct answer. Total of 23 points. 

1. Which of the following does not kill
    endospores? 
    a. Autoclave 
    b. Incineration 
    c. Hot air sterilization
    d. Free flowing steam
    e. None of these

2. Which of the following is best to sterilize heat
    labile solutions? 
    a. Incineration 
    b. Autoclave 
    c. Membrane filtration 
    d. Boiling water
    e. Pasteurization

3. Which of the following substances can
    sterilize? 
    a. 70% Ethanol
    b. Sodium benzoate 
    c. 8% Formaline 
    d. Sodium hypochlorite
    e. Betadine

4. Which of the following is used for surgical hand
    scrubs? 
    a. Cresyl acetate 
    b. Chlorine bleach 
    c. Chlorhexidine 
    d. Tincture of iodine
    e. Ethanol

5. Which of the following is not a heavy metal
    product? 
    a. Argyrol 
    b. Mercuric bichloride 
    c. Thimerosal 
    d. Halazone
    e. Zinc oxide 

6. These agents are also usually sterilants. 
    a. bactericide 
    b. virucide 
    c. sporicide 
    d. disinfectant
    e. germicide

7. Which of the following is not true about
    quaternary ammonium compounds? 
    a. Greater activity against gram-positive
        bacteria. 
    b. Outer membrane of gram-negative bacteria
        decreases effectiveness.
    c. Viricidal against hepatitus viruses. 
    d. Ineffective against tubercule bacillus. 
    e. None of the above

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8. Which of these disinfectants acts by protein
    oxidation? 
    a. Phenolics 
    b. Aldehydes 
    c. Halogens 
    d. Alcohols
    e. All of these

9. Which of these is an alkylating agent? 
    a. Halazone 
    b. Hydrogen peroxide 
    c. Betadine 
    d. bleech
    e. ethylene oxide

10. Which of the following treatments is the most
     effective for pasteurization of milk? 
     a. 62.9C for 30 min. 
     b. 71.6C for 15 sec. 
     c. 61.7C for 30 min. 
     d. Only a and b.
     e. Only b and c.

11. Which of the following treatments does not
      yield a sterile product? 
      a. Moist heat at 121.5 C for 15 min. 
      b. Moist heat at 135 C for 3 min. 
      c. Moist heat at 71.6C for 15 sec. 
      d. Dry heat at 160C for 3 hr. 
      e. None of the above. 

12. A classmate is trying to determine how a
      disinfectant might kill cells. You observed
      that when he spilled the disinfectant in your
      reduced litmus milk, the litmus turned blue
      again. You suggest to your classmate that 
      a. The disinfectant might inhibit cell wall
          synthesis. 
      b. The disinfectant might oxidize molecules. 
      c. The disinfectant might inhibit protein
          synthesis. 
      d. The disinfectant might denature
             proteins. 

      e. He take his work away from yours. 

13. Which of the following pairs is not correctly
      matched? 
      a. AgNO3 - ophthalmia neonatorum 
      b. Betadine - ophthalmia neonatorum 
      c. Cresyl acetate - antiseptic and analgesic 
      d. 10% H2O2 - deep wounds 
      e. None of these

14. Which of the following statements is true
      regarding use non-germicidal soaps over a
      four day period. 
      a. non-germicidal soaps have a persistant
          effect on skin over time. 
      b. non-germicidal soaps reduce bacterial
          count by half over four days. 
      c. non-germicidal soaps are just as effective
         as germicidal soaps in reducing microbial
         contamination. 
      d. microbial count actually increases two-fold
          using non-germicidal soaps. 
      e. there is no sustained effect of
          non-germicidal soaps on reduction of
          microbial contamination

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15. All of the following antibiotics inhibit protein
      synthesis except 
      a. Chloramphenicol. 
      b. Tetracycline. 
      c. Erythromycin. 
      d. Streptomycin.
      e. Rifampin. 

16. Effects of antimicrobial agents on cell walls of
      bacteria include blocking its synthesis,
      digesting it, or breaking down its surface.
      Which of the following is mismatched? 
      a. penicillin - blocks synthesis 
      b. lysozyme - digests it 
      c. lystophin - digests it 
      d. detergents - disrupts cell wall 
      e. alcohol - blocks synthesis 

17. All of the following act by competitive
      inhibition except 
      a. Dapsone. 
      b. Isoniazid. 
      c. Streptomycin. 
      d. Sulfonamide.
      e. None of these.

18. Which of the following antibiotics are used to
      treat fungal infections? 1-Aminoglycosides
      2-Cephalosporins 3-Griseofulvin 4-Polyenes
      5-Bacitracin
      a. 1, 2, and 3 
      b. 3 and 4 
      c. 3, 4, and 5 
      d. 4 and 5 
      e. All of the antibiotic

19. These agents work as microbicidal agents
      because they lower surface tension of cell
      membranes. 
      a. penicillin 
      b. surfactants 
      c. lysozyme 
      d. metallic ions 
      e. dry heat 

20. In testing for the drug susceptibility of
      microorganisms, the concept of therapeutic
      index is 
      a. the smallest concentration of drug that
          visibly inhibits growth. 
      b. the zone of inhibition around a disc in a
          disc-diffusion technique. 
      c. the largest zone size compared to the
          smallest zone size. 
      d. the ratio of the drug's toxic dose to its
          minimum effective dose. 
      e. both b and c are correct. 

21. Which of the following descriptions of
      antiviral chemotherapeutic agents are
      mismatched? 
      a. acyclovir - herpes simplex virus 
      b. ribavirin - respiratory syncytial virus (RSV) 
      c. azidothymidine - AIDS 
      d. interferon - produced naturally by infected
          animals 
      e. none of these

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22. Which of the following statements regarding
      antifungal agents is incorrect? 
      a. amphotericin B - systemic fungal
          infections 

      b. nystatin - candidiasis 
      c. griseofulvin - dermatophytic infections 
      d. flucytosine - dermatophytic infections 
      e. none of these 

23. Uses of antiparasitic drugs includes all of the
      following except? 
      a. mebendazole - malaria 
      b. quinine - malaria 
      c. chloroquine - malaria 
      d. metronidazole - amebicide 
      e. metronidazole- Trichomonas

Part B Directions- Matching. Match the physical
method on the left with the statement on the
right. Multiple answers are possible. Total of 12
points. 

A. scrubbing
B. sedimentation 
C. mechanical disruption 
D. desiccation 
E. cold temperature
F. osmotic pressure
G. sunlight 
H. ultraviolet light
I. filtration 
J. microwave 
K. gamma rays 

__A__the first step in many disinfecting
          processes.
__E__works by slowing down enzymatic
          processes. 
__F__employed in preserving jams and jellies.
__G__mode of action is photo-oxidation.
__C__ultrasonic vibrations. 
__D__important in helping to stop fungal
          infection.
__D__used to preserve powdered drugs.
__F__not effective against halophitic organisms. 
__J__used to disinfect natural pigments in
          cosmetics. 
__H__causes thymine dimers
__H,J_non-ionizing radiation.

Exam II Page 5 

Part C Directions Matching. Write the letter (s) of
the term in the space next to the description that
it matches. Two points for each correct letter.
Total of 30 points.
A. iodine
B. isoniazid
C. flucytosine
D. ammonium hydroxide
E. chlorine
F. betadine
G. methicillin
H. bile salts
I. phenols
J. griseofulvin
K. spectinomycin
L. polymyxin B
M. streptomycin
N. benzalkonium chloride
O. erythromycin
P. rifampin
Q. dapsone
R. benzoic acid
S. phenoxymethyl penicillin
T. amphotericin B
U. lysine
V. tetracycline
W. vancomycin
X. procaine penicillin
Y. nystatin
Z. miconazole

_W_ from Streptomyces species. DOC for
         methicillin resistant organisms.
_X__ repository penicillin.
_N__ cationic detergent. 
_L__ polypeptide antibiotic from Bacillus species,
         used in topical preparations. 
_H__ anionic detergent. 
_G__ semisynthetic penicillin used for
         beta-lactamase resistant organisms. 
_B__ antimetabolite whose structure resembles
         nicotinamide, and is used against
         tuberculosis. 
_K__ aminoglycoside used for resistant
         gonorrhea. 
_O__ macrolide antibiotic, inhibits protein
         synthesis, DOC for Legionnaires disease
         and Pertusis. 
_J__ DOC for dermatophytes. Interferes with RNA
         synthesis. 
_Q__ sulfone used against Mycobacterium leprae. 
_M__ aminoglycoside used for Plague and severe
         tuberculosis. 
_V__ a penicillin substitute used for people
         hypersensitive to penicillin. 
_P__ inhibits RNA synthesis and is a first line
         drug against tuberculosis. 
_C__ Inhibits RNA synthesis and is DOC for
         systemic mycoses 

Exam II Page 6 

Part D Directions- Essay. Answer each question in
the space provided. The value of each question is
indicated in parenthesis. Total of 35 points. 

1. Discuss the influence of concentration (0.1, 1,
    and 5 %) of phenol on its cidal activity as
    Influenced by time. (3 pt)
0.1%-indefinite-static
1%-20 to 30 min-cidal
5%- 2 to 3 min-cidal

2. When discussing the effectiveness of an agent
    in controlling microorganisms, one factor
    related to the organism is its previous history.
    Discuss how the previous history affects the
    ability of an agent to control microorganisms.
    (3 pt)
Young (log phase)- easy to kill since metabolically active.
mature (stationary phase)- hard to kill since low metabolism, capsules.
very old ( death phase)- easy to kill since sitting in toxic wastes.

3. What are the modes of action of dry heat as a
    method of controlling microorganisms? (3 pt)
dehydration- remove water necessary for enzymes.
protein oxidation
protein coagulation after prolonged heating

4. Why is moist heat considered more destructive
    than dry heat? (4 pt) 
quicker penetration and faster destruction due to moisture

5. Describe the use of chemicals which are protein
    coagulants. Are they narrow or broad
    spectrum? Are they used systemically or
    topically? Explain. (6 pt) 
broad spectrum. used topically since protoplasmic poisons.

Exam II Page 7 

6. What are the two common pore diameters of
    microbiological filters? Discuss whether they
    sterilize or disinfect. (4 pts)
0.45 micrometers- disinfects
0.2 micrometers- disinfects since viruses (0.02 micrometers) can pass through

7. Compare the effectiveness of methanol,
    ethanol and isopropanol as agents in
    controlling microorganisms. Which is more
    effective and why? Are they sterilants or
    disinfectants? Explain. (6 pts) 
isopropyl most effective since higher molecular weight disinfectants since not effective against spores

8. Explain the modes of action (i.e., how an
    active group is converted to an inactive group)
    for non-specific chemical combination. (6 pt)
protein oxidation- E-SH (sulfhydryl) group > E-S-S-E (mercaptide) inactive
alkylating agent- CH2O (formaldehyde) + E-SH > inactive E-S-CH2-OH