Microbiology 
Exam I-1998            Name _________________ 

Part A Directions:Multiple choice. Circle the correct answer. Total of 30 points. 

1. In this field of microbiology the aim is to
    monitor and control the spread of disease in
    communities.
    a. immunology 
    b. epidemiology 
    c. dairy microbiology 
    d. biotechnology
    e. industrial microbiology

2. Since most microorganisms encountered in
    microbiology will fall between 100 m and 10
    nm in overall dimension, observation would
    require use of which of the following
    techniques?
    a. human eye only
    b. light microscope only 
    c. light microscope and electron microscope 
    d. electron microscope only 
    e. human eye and light microscope 

3. Resolving power is:
    a. ability to enlarge objects 
    b. ability to show detail 
    c. the change in angle of the light ray as it
        passes into the lens 
    d. use of a single magnifying lens. 
    e. use of a second magnifying lens. 

4. The system for organizing, classifying, and
    naming living things is 
    a. nomenclature 
    b. taxonomy 
    c. taxa 
    d. identification 
    e. classification 

5. The scientific names of bacteria are always a
    combination of 
    a. the kingdom name followed by the division
        name 
    b. the class name followed by the order
         name 

    c. the family name followed by the genus
        name 
    d. the generic name followed by the common
        name 
    e. the generic name followed by the species
         name 

6. The traditional mainstay of bacterial
    identification has been: 
    a. biochemical characteristics 
    b. serological analysis 
    c. G + C base composition 
    d. DNA analysis using genetic probes 
    e. Nucleic Acid Sequencing and rRNA analysis. 

7. According to Bergey's Manual of Systematic
    Bacteriology, the mycoplasmas are placed into
    the Division 
    a. Gracilicutes 
    b. Firmicutes 
    c. Tenericutes 
    d. Mendosicutes 
    e. Mr. Smith's a cute 

Exam I 1998, Page 2 

8. The cells of bacteria can be categorized
    according to their arrangement. A cubical
    packet of eight cocci is known as 
    a. diplococci 
    b. tetrads 
    c. streptococci 
    d. staphylococci 
    e. sarcina 

9. In the Gram stain, bacterial cells are first
    stained with crystal violet, then iodine.
    Following this the cells are rinsed with alcohol.
    Gram negative cells at this point would have
    what color? 
    a. purple 
    b. red 
    c. colorless 
    d. yellow 
    e. green 

10. In addition to Gram-negative and
     Gram-positive bacteria, some bacteria have
     unique lipids, such as mycolic acid, that
     impart a waxy nature to their cell wall. This
     difference in cell wall is the basis for use of
     the following staining procedure: 
     a. Gram stain 
     b. Simple stain 
     c. Spore stain 
     d. Acid-Fast stain 
     e. Capsule stain 

11. A contaminated culture is 
      a. the observable growth that appears in or
          on the medium
      b. free of other living things except the one
          being studied 
      c. holds two or more identified
          microorganisms 
      d. was once pure or mixed but now has
          microbes of uncertain identity 
      e. a container that grows only a single known
         species of microorganism. 

12. The temperature which promotes the fastest
      rate of growth and metabolism 
      a. minimum 
      b. maximum 
      c. optimum 
      d. lowest temperature that permits a
          microbes growth 
      e. the highest temperature at which growth
         and metabolism can proceed. 

13. A psychrophile is a microorganism that has an
      optimum temperature 
      a. between 20 to 40 C 
      b. below 15 C and is capable of growing
            at 0
C
      c. greater than 45 C 
      d. at human body temperature 
      e. greater than 50 C 

14. A microaerophile 
      a. grows in the presence of normal oxygen
          concentration 
      b. does not grow in the presence of normal
          oxygen concentration 
      c. does not require oxygen but is capable of
          growth in the absence of oxygen 
      d. will die if exposed to oxygen 
      e. requires small amounts of oxygen in
          metabolism 

Exam I 1998, Page 3 

15. When studying bacterial growth curves, the
      relatively flat period when the population
      appears not to be growing is this phase 
      a. death phase 
      b. log phase 
      c. stationary phase 
      d. lag phase 
      e. exponential phase 

16. This type of intermicrobial exchange of
      genetic material is the only one that involves
      direct contact. 
      a. transduction 
      b. translation 
      c. lysogenic conversion 
      d. conjugation 
      e. phenotypic transformation 

17. Yeast have which of the following
      characteristics? 
      a. procaryotic, unicellular 
      b. procaryotic, multicellular 
      c. eucaryotic, unicellular, absorptive
          heterotroph   

      d. eucaryotic, multicellular, absorptive
          heterotroph 
      e. eucaryotic, multicellular, photosynthetic
          autotroph 

18. This discipline is the study of protozoal and
      helminth diseases. 
      a. phycology 
      b. mycology 
      c. protozoology 
      d. parasitology 
      e. immunology 

19. The most important role of microorganisms is 
      a. they cause 5 million deaths annually from
          diarrheal disease 
      b. they are used as research tools for
          production of hormones such as insulin 
      c. they are saprobes and break down
            organic
matter into inorganic chemicals 
      d. production of foods such as beer and
          yogurt 
      e. destruction of crops 

20. In bright field microscopy, all of the following
      statements are true EXCEPT 
      a. objects may be magnified 1,000 to 2,000
          times their diameter 
      b. resolution is better using red light than
             blue light 
      c. objects appear darker than the field of
          view 
      d. the limit of resolution is 200 nanometers 
      e. this technique is not useful for the study
          of most viruses 

21. This technique is useful in diagnosis of
      syphilis. 
      a. Compound light microscope 
      b. Phase contrast microscope 
      c. Darkfield microscope 
      d. Fluorescent microscope 
      e. Electron microscope 

Exam I 1998, Page 4 

22. Uses an ultraviolet light source. 
      a. Compound light microscope
      b. Phase contrast microscope 
      c. Darkfield microscope 
      d. Fluorescent microscope 
      e. Electron microscope 

23. Which of the following is NOT a
      distinguishing characteristic of Bacteria
      a. Their DNA is not enclosed within a
          membrane. 
      b. They lack membrane-bounded organelles. 
      c. They have cell walls containing
          peptidoglycan. 
      d. They are unicellular. 
      e. None of these. 

24. Which of the following is NOT true about a
      gram-positive cell wall? 
      a. It maintains the shape of the cell. 
      b. It contains lysine 
      c. It protects the cell in a hypertonic
         environment. 
      d. It contains teichoic acids. 
      e. None of these. 

25. Which of the following is NOT a characteristic
      of the plasma membrane? 
      a. Maintains cell shape 
      b. Composed of a phospholipid bilayer 
      c. Contains proteins 
      d. outermost living part of cell 
      e. Selectively permeable 

26. Which of the following statements is true? 
      a. Endospores are for reproduction. 
      b. Endospores allow a cell to survive
            adverse
environmental changes. 
      c. Endospores are heat sensitive. 
      d. A cell produces one endospore and keeps
          growing. 
      e. A cell can produce many endospores. 

27. Which of the following is NOT true about the
      glycocalyx? 
      a. It may be composed of polysaccharide. 
      b. It may be composed of polypeptide. 
      c. It may be responsible for virulence. 
      d. It is used to adhere to surfaces. 
      e. None of these. 

28. Which of the following pairs is mismatched? 
      a. Capsule-prevents phagocytosis 
      b. fimbriae-adherence 
      c. flagella-motility 
      d. Cell wall-prevents plasmolysis 
      e. Plasma membrane-selectively permeable 

29. The addition of which of the following to a
      culture medium will neutralize acids? 
      a. Peptones 
      b. Sugars 
      c. vitamins 
      d. Heat 
      e. Carbon 

Exam I 1998, Page 5 

30. Which of the following is an advantage of the
      standard colony plate count? 
      a. Both dead and live cells are counted. 
      b. It is an indirect method. 
      c. It determines viable cells only. 
      d. Not all organisms grow on the enumeration
          medium. 
      e. None of these. 

Part B Directions: Short Answer. Answer the questions in the space provided. Total of 20 points. 

1. True or False? A compound light microscope
    with a resolving power of 0.3 micrometers
    would be able to discern two objects separated
    by 200 nanometers. __F________

2. Most bacteria grow best at pH __7.0________ 

3. A phase contrast microscope is modified using
    an annular diaphragm and ?
                            phase-shifting element

Exam I 1998, Page 6

4. Normal bacteria (those not possessing large
    amounts of wax in their cell walls) may be
    seen with a Fluorescent microscope using this
    technique. fluorescent antibody technique

5. True or False? A Differential Interference
    Contrast microscope provides a high degree of
    contrast between the object and the field of
    view due to the presence of an exciter filter
    which focuses the incident rays of
    light.___F_____

6. Bacteria with faulty skins (i.e. without murein),
    are classified into the Division? mendosicutes

7. An example of an artificial classification would
    be? phone book, Whittaker's, Bergey's

8. Streptococcus pyogenes is generally resistant
    to phagocytosis since its capsule contains ? ,
    which is also a cementing material in animal
    cells. hyaluronic acid 

9. True or False? A change in bacterial cell shape

    throughout a normal growth curve is an
    example of genetic recombination.__F_______

10. Extrachromosomal pieces of DNA found in
      bacteria are called? _plasmids

Part C Directions: Essay. Answer the questions in
the space provided. The value of each question is
indicated in parenthesis. Total of 50 points.

1. Use the diagrams below to answer the
    following questions. Justify your answer (i.e.,
    state why you feel your answer is correct).(8
    pts) (see p. 98 in text: right-hand picture
     is #1,  left-hand is #2)

    a. Which diagram illustrates a gram-negative
        cell wall?
        a. 1
        b. 2
        c. Both 1 and 2
        d. Neither 1 nor 2
        e. Can't tell
since has outer membrane
    b. Which diagram illustrates a toxic cell wall?
        a. 1
        b. 2
        c. Both 1 and 2
        d. Neither 1 nor 2
        e. Can't tell
contains lipopolysaccharides (LPS) in outer membrane

Exam I, page 7

2. This is a typical bacterial growth curve. Name
    and define the indicated phases. (6 pts)
(see page 214 text)
A- lag phase-population appears not to be growing
B-log growth phase- cells divide geometrically
C-stationary phase.rate of cell death balances
    rate  of cell multiplication
D- log death phase-cells die exponentially

3. Below are three different culture media. Use
    them to answer the following questions.
    Justify your answer (i.e., state why you feel
    your answer is correct). (6 pts)

Medium A Medium B Medium C
1g Na2HPO4
0.5g KNO3
0.4g MgSO4
1.2g CaCl2
4.5g NaHCO3
10mg Lysine
5g Glucose
10mg Thiamine
1.5g Sucrose

5g Glucose
2g Peptone
1g Beef heart
3g Thiamine
1g Na2HPO4

a. Which medium (media) is (are) chemically
    defined?
        a. A 
        b. B 
        c. A and B 
        d. A and C 
        e. None of these
know exactly what and how much of each chemical

b. Which medium is designed for an autotroph? 
        a. A 
        b. B 
        c. A and B 
        d. A and C 
        e. None of these
contains inorganic nitrogen

4. Describe how the bright field microscope is
    modified for fluorescent microscopy. Give an
    example of its use (8 pts).
intense light source
exciter filter- filters out visible wavelengths
barrier filter-filters out ultraviolet light
fluorescent stain- e.g. auramine O, stains organisms
with high wax content

Exam I, page 8 

5. Describe the three most common shapes of
    bacteria and their average sizes. (6 pts) 
coccus- 1 micrometer
bacillus- 0.5 micrometers wide to 2 micrometers long
spirilla- 0.5 micrometers wide to 1-14 micrometers long

6. Describe two processes by which bacteria
    can become resistant to antibiotics. (8 pts) 
mutation- change in DNA. Rare.
Resistance plasmids- plasmid transferred during conjugation. More common.

7. Explain the differences between
    transduction and lysogenic conversion. (8 pts)
Both involve viruses.
Transduction- piece of bacterial DNA is transferred. Imparts new characteristic. Genetic recombination.
Lysogenic conversion- not genetic recombination. Virus DNA integrates with bacterial DNA. Imparts new characteristics.