Biology 2261
Spring 1999
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Name
First Examination
Be sure to put your name on the mark-sense sheet.
Put your name on the exam booklet. Both the exam booklet and the mark-sense
sheet must be turned in at the end of the period.
You may write in the exam booklet, but only the mark-sense sheet will be graded. No
other paper, scratch paper, etc., may be used.
Students must turn in the exam before leaving the room for any reason. A student may
not continue working on the exam after having left the room.
Multiple Choice. 50 questions, 2 pt each.
1.
Which of the following statements best summarizes Koch’s postulates?
(a)
Bacteria and other simple microorganisms can spontaneously form from simple
chemical interactions in nonliving organic matter.
To demonstrate that a disease condition is caused by an infectious microorganism,
one must identify the microorganism in a statistically significant (5% confidence
level) proportion of the diseased population.
Bacteria and other simple microorganisms do not form from spontaneous
generation in nonliving matter, but from reproduction of living microbial cells.
To demonstrate that a disease condition is caused by an infectious microorganism,
one must isolate the microorganism from an infected individual, infect a healthy
experimental animal with a pure culture of the microorganism, demonstrate the
development of the disease symptoms in the experimental animal, and re-isolate
the same microorganism from the experimental animal.
To prevent the spread of infectious disease, infected individuals must be isolated
from healthy individuals, and contaminated clothing and other objects must be
sterilized.
(b)
(c)
(d)
(e)
2.
In bacteria, antibiotic resistance and ability to conjugate are usually encoded by
(a)
(b)
(c)
chromosomal DNA
plasmid DNA
ribosomal RNA
3.
A disease that is normally present in a certain percentage of a population is a(n)
(a)
(b)
(c)
communicable disease
contagious disease
noncommunicable disease
(d)
(e)
(d)
(e)
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viral DNA
nuclear DNA
epidemic disease
endemic disease
4.
Certain strains of the bacterium Corynebacterium diphtheriae contain an extra
gene that codes for an exotoxin. These strains can cause a severe infection called
diphtheria. Other strains that do not have the gene for the exotoxin produce no
infection in humans. Which of the following statements best describes the
relationship between strains that produce the exotoxin and those that do not?
(a)
Strains that produce the toxin are acute, and strains that do not produce the toxin
are chronic.
Strains that produce the toxin are primary, and strains that do not produce the
toxin are secondary.
Strains that produce the toxin are localized, and strains that do not produce the
toxin are systemic.
Strains that produce the toxin are virulent, and strains that do not produce the
toxin are nonvirulent.
Strains that produce the toxin are epidemic, and strains that do not produce the
toxin are endemic.
(b)
(c)
(d)
(e)
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The following information pertains to questions 5 - 8.
In each of the following questions, a description of a microorganism is given. Based on
the description, determine which of the following choices best describes the
microorganism.
(a)
The microorganism is prokaryotic.
(b)
The microorganism is eukaryotic.
(c)
The microorganism is a virus.
5.
The organism responsible for anthrax consists of rod-shaped cells. Each cell is
surrounded by a thick layer of highly cross-linked peptidoglycan. The DNA of the
cell is a circular DNA molecule found in the nucleoid region of the cell’s
cytoplasm. Cellular respiration is carried out by proteins located in the cell’s
plasma membrane.
6.
Rickettsia rickettsii is responsible for the condition known as Rocky Mountain
Spotted Fever. Although this organism grows only within an infected host, it has
its own DNA and RNA to direct the synthesis of its protein and to control its cell
division. Its DNA is found in the nucleoid region of its cytoplasm, but there is no
nuclear membrane surrounding the DNA.
7.
Euglena gracilis is a member of the kingdom Protista. It is a free-living organism
often found on the surfaces of ponds. The most notable feature of this singlecelled organism is its chloroplast, a membrane-enclosed organelle that absorbs
light energy and uses it to manufacture carbohydrates. The organism is motile by
means of a flagellum that moves back and forth in a whip-like motion to propel
the organism forward.
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8.
When the pathogen responsible for dengue fever penetrates its host cells, its RNA
is released from the protein shell. Within the host cell, the dengue RNA directs
the synthesis of protein and RNA molecules that are assembled into many more
infectious dengue particles.
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The following information pertains to questions 9 - 11. Thioglycolate broth is a
differential medium used to determine the oxygen requirements of bacteria. When a test
tube of thioglycolate broth is prepared, an oxygen gradient is established. This means that
there is a high concentration of oxygen at the surface of the broth, less oxygen in the
middle of the tube, and no oxygen at the bottom of the tube. The following choices are
used for questions 9 - 11.
(a)
(b)
(c)
strict aerobe
strict anaerobe
facultative anaerobe
(d)
(e)
aerotolerant anaerobe
microaerophile
9.
If cells of a bacterial species grow equally well throughout a thioglycolate broth
tube, to which group does the species belong?
10.
If cells of a bacterial species grow in one narrow band somewhere in the middle of
the tube between the surface and the bottom of the tube, to which group does the
species belong? (Note: the bacteria do not grow on the surface nor on the bottom,
but in a narrow band in the middle.)
11.
If cells of a bacterial species grow throughout a thioglycolate broth tube, but they
grow better at the top of the tube than at the bottom of the tube, to which group
does the species belong?
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The following information pertains to questions 12 and 13.
The graph below shows the growth rate of a certain bacterial species at different
temperatures. In this graph, a larger growth rate value indicates that the bacteria grew
faster (divided more frequently) at that temperature.
0.05
0.045
Growth Rate (1/min)
0.04
0.035
0.03
0.025
0.02
0.015
0.01
0.005
0
0
10
20
30
40
50
60
70
80
90
100
Temperature (degrees Celcius)
12.
Based on the data, which of the following terms best describes the organism?
(a)
(b)
(c)
(d)
(e)
Extreme thermophile
Moderate thermophile
Mesophile
Psychrophile
Halophile
13.
Based on the data, which of the following conclusions can you reach?
(a)
(b)
(c)
(d)
The cells of this bacterial species cannot survive at temperatures above 75C.
The cells of this bacterial species cannot survive at temperatures below 45C.
Both (a) and (b) are valid conclusions based on the data.
Neither (a) nor (b) are valid conclusions based on the data.
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14.
Which of the following regions of the human body is free of normal flora under
normal conditions of health?
(a)
(b)
(c)
upper respiratory tract
skin surfaces
large intestine
(d)
(e)
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more than one of the above
none of the above
15.
Which of the following best describes the structure of peptidoglycan?
(a)
(b)
a polymer of glycerol or ribitol linked by phosphate groups
a polymer of alternating glucosamine and ethanolamine units linked by ester
bonds
a polymer of -hydroxybutyrate units linked by pentapeptide bridges
a polymer of alternating N-acetylglucosamine and N-acetylmuramic acid units
linked by glycosidic bonds
a polymer of O chain polysaccharide and core polysaccharide attached to a Lipid
A molecule
(c)
(d)
(e)
16.
How does the peptidoglycan layer of archaeobacteria differ from that of the gramnegative bacteria?
(a)
(b)
(c)
It is much thicker.
(d)
It is much more highly crosslinked.
(e)
It has strands of teichoic acid inserted into it.
17.
Adjacent chains of peptidoglycan may be covalently crosslinked by
(a)
(b)
(c)
(d)
(e)
short chains of lipopolysaccharide molecules.
short chains of amino acids.
metachromatic granules
More than one of the above.
None of the above.
18.
Phenylketonuria is an inborn error of metabolism in humans that results from the
genetic inability to make an enzyme necessary for the break down of the amino
acid phenylalanine. Consider the following statements about phenylketonuria.
I.
II.
III.
IV.
V.
(a)
(b)
(c)
(d)
(e)
More than one of the above
None of the above.
Phenylketonuria is a disease.
Phenylketonuria is a chronic infection.
Phenylketonuria is a primary infection.
Phenylketonuria is an noncommunicable infection.
Phenylketonuria is an endemic infection.
All statements (I, II, III, IV, and V) are true.
Only statements I and II are true.
Only statements I and III are true.
Only statements I, II, and III are true.
Only statement I is true.
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The following choices are used for questions 19 - 20.
(a)
(b)
(c)
reservoir of infection
fomite
human carrier
(d)
(e)
animal vector
aerosol
19.
Which is the best (most specific) term to describe an insect which carries
pathogenic microbes on its feet from garbage to human food sources?
20.
Which is the best (most specific) term to describe an inanimate object that is
contaminated with pathogenic microbes?
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21.
The period of time between the colonization of a pathogen into its host and the
appearance of the initial symptoms of infection is called the
(a)
(b)
(c)
prodromal period
convalescent period
invasive period
22.
Which of the following statements is true?
(a)
(d)
(e)
Endotoxins produce varied effects such as neurotoxic or protein inhibition effects,
but exotoxins produced generalized irritation and inflammation of epithelial
surfaces.
Endotoxins are found attached to the cell wall of certain bacteria, but exotoxins
are secreted toxins that may exhibit their effect independently of the presence of
the bacteria.
Exotoxins include the neurotoxins of botulism and tetanus, while endotoxins
include the enterotoxin of Staphylococcus aureus.
More than one of the above statements are true.
None of the above are true.
23.
Metachromatic granules are composed of
(a)
(b)
(c)
sulfur
lipid
phosphate
(b)
(c)
(d)
(e)
(d)
(e)
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incubation period
decline period
polysaccharide
protein
24.
The O side chain antigen is a component of
(a)
(b)
(c)
(d)
(e)
the outer membrane of the gram-negative cell wall.
the hook-and-rotor assembly of a bacterial flagellum.
the spore coat of a bacterial endospore.
the inner leaflet of a bacterial plasma membrane.
the photosynthetic electron transport chain of a chlorplast.
25.
In bacteria that possess flagella, a change of direction in movement is
accomplished when
(a)
ions are pumped through porin protein channels, causing the electrical polarity of
the cell surface to change from positive to negative.
ions are pumped through porin protein channels, causing the electrical polarity of
the cell surface to change from negative to positive.
electrons are transported through a series of membrane proteins, causing an
increase in the cytoplasmic concentration of ATP.
the rudder proteins of the flagellar basal body undergo a conformational change,
altering the angle between the flagellar filament and the cell surface.
the direction of the flagella’s spin reverses, causing the cell to tumble and change
its orientation in a random fashion.
(b)
(c)
(d)
(e)
26.
This person, in the 1800s, suggested that hand-washing by physicians could
reduce the transmission of infection to women during labor and delivery.
(a)
(b)
(c)
van Leeuwenhoek
Koch
Pasteur
(d)
(e)
Semmelweis
Snow
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The following information pertains to questions 27 - 29.
A healthy child was exposed to a virulent strain of the bacterium Hemophilus influenzae.
27.
Within several days, she developed severe pharyngitis due to the Hemophilus
infection. Which of the following statements best describes the Hemophilus
infection at this point?
(a)
(b)
(c)
It is a primary, systemic infection. (d)
It is a primary, localized infection. (e)
It is a secondary, systemic infection.
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It is a secondary, localized infection.
It is an acute, subclinical infection.
28.
After two more days, the infection spread to her bloodstream. She developed
bacterial septicemia and meningitis. Which of the following statements best
describes the Hemophilus infection at this point?
(a)
(b)
(c)
It is a primary, systemic infection. (d)
It is a primary, localized infection. (e)
It is a secondary, systemic infection.
29.
While in the hospital, the sick child was exposed to the human respiratory
syncytial virus (RSV). The virus infected her lungs causing viral pneumonia.
There was no evidence that the RSV virus had spread beyond her lungs. Which of
the following statements best describes the RSV infection?
(a)
(b)
(c)
It is a primary, systemic infection. (d)
It is a primary, localized infection. (e)
It is a secondary, systemic infection.
It is a secondary, localized infection.
It is an acute, subclinical infection.
It is a secondary, localized infection.
It is an acute, subclinical infection.
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30.
Look at the names of each of the bacteria listed below.
I.
II.
III.
IV.
V.
Bacillus megaterium
Group A streptococcus
tuberculosis
Diphtheria bacillus
Staphylococcus epidermidis
Which of the names is (are) written according to the formal rules of systematic
binomial nomenclature?
(a)
(b)
(c)
II and IV only
I, III, and V only
I, III, IV, and V only
(d)
(e)
I and V only
I, IV, and V only
31.
A system of classification in which organisms are grouped together to reflect
genetic similarity and evolutionary relatedness is a
(a)
(b)
(c)
binomial system
phenetic system
nomenclature system
(d)
(e)
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parthogenic system
phylogenetic system
32.
A sample of mucous from the trachea of a healthy volunteer was collected by
having the volunteer cough up the mucous and spit it into a sterile cup. A colony
count revealed the presence of 6500 viable bacterial cells per ml of mucous. A
second sample was taken from the same volunteer on the same day, but it was
taken by withdrawing it directly from the trachea using a sterile syringe. In the
second sample, a colony count revealed that no bacteria were present. Which of
the following statements gives the most likely explanation of these results?
(a)
A strong immune response destroyed the normal flora of the lower respiratory
tract between the time that the first sample was taken and the time that the second
sample was taken.
The lower respiratory tract is free of normal flora. Bacteria from the oral cavity
were responsible for bacterial contamination in the first sample.
The bacteria in the first sample developed from the process of spontaneous
generation.
All of the normal flora of the lower respiratory tract were expelled when the first
sample was taken.
(b)
(c)
(d)
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The following choices are used for questions 33 - 36.
(a)
Protein A
(d)
collagenase
(b)
Lipid A
(e)
flagellin
(c)
Protein M
33.
Which substance contributes to the adhesion of pathogenic Streptococcus
pyogenes cells to host tissue?
34.
Which substance acts as a bacterial endotoxin?
35.
Which substance contributes to motility?
36.
Which substance is a component of the gram-negative bacterial cell wall
structure?
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The following choices are used for questions 37 - 38.
(a)
coagulase
(d)
leukocidin
(b)
streptokinase
(e)
hemolysin
(c)
hyaluronidase
37.
This enzyme triggers clot formation.
38.
This enzyme destroys a key carbohydrate component between host cells which
loosens the connection between the cells in host tissue.
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39.
The staphylococcal enterotoxin
(a)
(b)
(c)
(d)
(e)
is composed solely of Lipid A.
is among the most heat-resistant of exotoxins.
can be destroyed by placing food in a refrigerator.
produces a condition of rigid paralysis.
is more lethal than the botulism toxin.
40.
Proteus vulgaris, a bacterium, is part of the normal colon flora in most people.
There is no direct benefit to the person in having this organism in the colon, and it
is not pathogenic. Which term best describes the relationship between Proteus
vulgaris and the humans it inhabits?
(a)
(b)
(c)
Mutualism
Parasitism
Commensalism
(d)
(e)
Syncytialism
Plagiarism
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The following choices are used for questions 41 - 42.
(a)
(b)
(c)
bacillus
coccus
vibrio
(d)
(e)
spirillum
spirochaete
41.
This term designates flexible, helical-shaped bacterial cells.
42.
This term designates comma-shaped bacteria.
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The following choices are used for questions 43 - 44.
(a)
(b)
(c)
streptococcus
staphylococcus
sarcina
(d)
(e)
diplococcus
tetrad
43.
This term designates spherical bacterial cells arranged in clusters.
44.
This term designates spherical bacterial cells arranged in cubical packets of eight
cells.
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The following choices are used for questions 45 - 47.
(a)
gram-positive bacteria
(d)
(b)
gram-negative bacteria
(e)
(c)
acid-fast bacteria
archaeobacteria
mycoplasmas
45.
The cells of this group are difficult to stain due to the high concentration of
mycolic acid in their cell walls.
46.
The enzyme lysozyme hydrolyzes the bonds between the monomer units of
peptidoglycan. Based on this information, which group do you predict should be
the most sensitive to the antimicrobial action of lysozyme?
47.
Teichoic acid is a cell wall polymer associated with this group.
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48.
Which of the following best describes the function of bacterial spores?
(a)
(b)
(c)
(d)
(e)
They provide a mechanism for bacterial reproduction.
They mediate the process of spontaneous generation in bacteria.
They induce positive and negative chemotactic responses in bacteria.
They help ensure the survival of the species during conditions of nutrient
depletion and waste buildup.
More than one of the above.
49.
How do the S strain and R strain of Streptococcus pneumoniae differ from each
other?
(a)
(b)
(c)
(e)
The strains belong to different genera.
The strains belong to different species.
Cells of the S strain are encapsulated and virulent, while cells of the R strain are
not encapsulated and not virulent.
Cells of the R strain are encapsulated and virulent, while cells of the S strain are
not encapsulated and not virulent.
More than one of the above choices is true.
50.
Which of the following statements is FALSE?
(a)
Gram-negative cells have an outer membrane containing lipopolysaccharide,
while gram-positive cells do not.
Gram-positive cells retain the crystal violet dye and stain purple or violet during
gram staining, while gram-negative cells do not.
Gram-positive cells can have teichoic acid in their cell walls, while gram-negative
cells do not.
Gram-negative cells have a thick layer of peptidoglycan in their cell wall
structure, while gram-positive cells do not.
(d)
(b)
(c)
(d)
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