1)
Answer parts a through VV.
a)
The scientist that contributed most to the development of pure
culture techniques was
Alexander Fleming.
Louis Pasteur.
Edward Jenner.
Robert Koch.
b)
The solidifying agent used most successfully in bacterial
nutrient media is
gelatin.
peptone.
agar.
starch.
c)
Prokaryotic cells divide by a process known as
conjugation.
mitosis.
binary fusion.
binary fission.
d)
In nature, bacteria
often grow in close association with many other kinds of
organisms.
may remain in a prolonged exponential phase.
frequently synthesize structures such as slime layers.
may adhere to surfaces by means of pili and slime layers.
All of the choices are correct.
e)
The simplest technique for isolating bacteria in growth media is
referred to as the
pour plate method.
streak plate method.
serial dilution method.
MPN method.
f)
Bacteria may be stored
on a slant in the refrigerator.
frozen in glycerol solution.
lyophilized.
in broth at 37°C.
on a slant in the refrigerator, frozen in glycerol solution AND
lyophilized.
g)
In the growth curve of a bacteria population, the bacteria are
rapidly increasing in number in the
lag phase.
exponential (log) phase.
stationary phase.
decline phase.
boomer phase.
h)
During which phase of growth are bacteria most susceptible to
antibiotics?
lag
stationary
exponential (log)
decline
i)
When doing experiments with bacteria
it is usually not necessary to standardize which stage of
growth is used.
it is best to use colonies as all the bacteria in a colony are
at the same stage of growth.
it is best to use bacteria from the same stage of growth.
the age of the bacteria is not important.
j)
During which phase of the bacterial growth curve does the total
number of viable cells decline?
stationary
lag
exponential
death
k)
The lag phase of the bacterial growth curve is marked by
a decrease in cell mass.
dormant, metabolically inactive cells.
metabolically active cells.
vigorously dividing cells.
l)
During which phase of the bacterial growth curve does a
bacterial population become much more resistant to harmful
conditions?
lag phase
exponential phase
stationary phase
late log phase
m)
In a rapidly multiplying bacterial population, cell numbers
increase
arithmetically.
logarithmically.
linearly.
indirectly.
n)
Generally the proteins of thermophiles
resist denaturation.
react more efficiently with DNA.
are easily denatured.
have a particular amino acid sequence that restricts bond
formation.
are easily denatured AND have a particular amino acid sequence
that restricts bond formation.
o)
A hot tub (approx. 104 deg. F or 40 deg. C) would most likely
contain
psychrophiles.
partiers.
thermophiles.
mesophiles.
p)
The optimal temperature for most human pathogens might be
expected to range from
35-40°C.
20-45°C.
15-25°C.
93-98.6°C.
q)
Mycobacterium leprae is typically found infecting
the ears, toes and fingers of its host due to its
requirement for well-oxygenated blood.
easy access to those parts.
need for cooler temperatures.
long incubation period.
r)
Organisms that require gaseous oxygen for metabolism are
referred to as
facultative aerobes.
obligate aerobes.
facultative anaerobes.
microaerophiles.
s)
Organisms that are indifferent to the presence of oxygen and do
not use it are
aerotolerant anaerobes.
facultative anaerobes.
obligate aerobes.
microaerophiles.
t)
Shake tubes are used to determine the
pH requirements for bacterial growth.
temperature requirements for bacterial growth.
oxygen requirements for bacterial growth.
salt requirements for bacterial growth.
u)
The optimum pH for growth of most species of bacteria is
pH 5.
pH 7.
pH 9.
pH 6.
v)
High concentrations of salt and sugar in foods
are useful in preserving the food.
tend to draw water out of a cell.
tend to force water into a cell, causing plasmolysis.
have no effect on water availability.
are useful in preserving the food AND tend to draw water out of
a cell.
w)
Small organic molecules that must be provided to bacteria in
order for them to grow are called
minerals.
growth factors.
water.
vitamins.
x)
Organisms that use organic molecules as their source of carbon
are called
chemotrophs.
organoheterotrophs.
heterotrophs.
autotrophs.
y)
Organisms that use CO2 as their source of carbon are
called
organotrophs.
heterotrophs.
autotrophs.
chemotrophs.
z)
Chemoheterotrophs
use sunlight as an energy source.
use pre-formed organic molecules as a carbon source.
use pre-formed organic molecules as an energy source.
use inorganic chemicals as an energy source.
use pre-formed organic molecules as a carbon source AND as an
energy source.
A)
Medically important bacteria are often
grown on agar containing blood.
grown at 37°C.
grown on agar containing chocolate.
grown at a pH of 5.
grown on agar containing blood AND grown at 37°C.
B)
Products which limit pH changes are often incorporated into
media and are referred to as
enzymes.
bases.
buffers.
acids.
C)
A medium that inhibits the growth of organisms other than the
one being sought is termed a(n)
synthetic medium.
specific culture medium.
selective medium.
enrichment medium.
D)
It is assumed that every colony observed on a streak plate arose
from a single bacterium.
True
False
E)
In microbiology, growth usually refers to an increase in size of
the bacteria.
True
False
F)
There are 5 stages of growth in an open system of culture.
True
False
G)
A single bacterial cell may multiply to form a visible
colony.
True
False
H)
Freezing is an effective means of destroying bacteria.
True
False
I)
Lister developed his ideas on prevention of infection during
medical procedures after studying the work of
Koch.
Pasteur.
Jenner.
Fleming.
J)
One of the first chemicals used by Lister to prevent surgical
infections was
alcohol.
iodine.
carbolic acid.
mercury.
K)
The process of killing or removing all of the microorganisms in
or on a material is termed
sterilization.
disinfection.
sanitation.
antisepsis.
L)
A sterile item is free of viable
microbes.
endospores.
viruses.
prions.
microbes, endospores AND viruses.
M)
A suffix used to describe a killing action would be
-static.
-cidal.
-cillin.
-tion.
N)
Pasteurization
is the use of heat to sterilize food products.
is the use of heat to reduce numbers of pathogenic/spoilage
bacteria in a food item to a safe level.
is a process which uses intense cold to kill microorganisms on
foods.
is a process which uses short bursts of radiation to kill
microorganisms on foods.
O)
Plain soap is very effective in controlling spread of
microorganisms because it is
bacteriostatic.
very effective at the mechanical removal of
microorganisms.
virucidal.
bactericidal.
P)
Nosocomial infections
are acquired at various social events.
are acquired while in the hospital.
occur because of a susceptible population and presence of
disease causing organisms.
are acquired at sporting events.
are acquired while in the hospital AND occur because of a
susceptible population and presence of disease causing
organisms.
Q)
To reduce or eliminate disease/spoilage causing organisms, food
is often subjected to
heat.
chemical additives.
radiation.
cold.
All of the choices are correct.
R)
Microbial death rates may be affected by
pH.
temperature.
the presence of organics.
All of the choices are correct.
S)
Moist heat kills microorganisms by
irreversible coagulation of proteins.
destruction of carbohydrates in the cell wall.
denaturation of nucleic acids.
dissolving the capsule.
T)
Boiling is not reliable for sterilization because
heat sensitive instruments may be destroyed.
heat resistant endospores are unaffected.
water boils at a higher temperature at lower altitudes.
viruses are more sensitive to heat than bacteria.
U)
Which are essentially equivalent treatments?
dry 200°C heat for 1.5 hours; wet 121°C heat for 15
minutes
dry 160°C heat for 1.0 hour; wet 200°C heat for 30 minutes
dry 121°C heat for 1.5 hours; wet 200°C heat for 15
minutes
dry 100°C heat for 2.0 hours; wet 100°C heat for 30
minutes
V)
Which of the following is not a sterilization method?
hot air oven
autoclave
pasteurization
filtration
W)
The autoclave treatment may be monitored by
heat-sensitive tape.
heat-resistant endospores
of Geobacillus stearothermophilus.
pressure indicators alone.
waiting for contaminants to appear on freshly poured
media.
heat sensitive tape AND heat-resistant endospores
of Geobacillus stearothermophilus.
X)
Commercial canning processes
are geared to
destroy Clostridium botulinum spores.
kill all endospores.
are especially needed on low acid foods.
are 12D processes (designed to kill 1012 endospores).
are geared to
destroy Clostridium botulinum spores,
are especially needed on low acid foods, AND are 12D (designed to
kill 1012 endospores) processes.
Y)
Generally, membrane filters are not used to remove
bacteria from liquids.
microorganisms from gases.
spoilage agents from alcoholic beverages.
enzymes.
Z)
Gamma irradiation
has not been approved for use on food.
can be used to either sterilize or pasteurize, depending on the
dose of radiation.
leaves some radioactive particles in the treated
substance.
usually kills by disrupting cell membranes.
AA)
Ultraviolet radiation at the bactericidal wavelength destroy
bacteria by
destroying endospores.
damaging nucleic acid.
preventing spore formation.
denaturing proteins.
BB)
Microwaves do not kill organisms directly but kill by
the heat they generate in a product.
generating free radicals.
generating toxins.
creating thymine dimers.
CC)
Alcohols are not reliably effective at destroying
vegetative bacteria.
enveloped viruses.
naked viruses.
endospores.
naked viruses AND endospores.
DD)
Glutaraldehyde
is, if given enough time, able to destroy all forms of
microbial life.
is very good for use on heat-sensitive medical items.
attacks lipids.
does not affect naked viruses.
is, if given enough time, able to destroy all forms of
microbial life AND is very good for use on heat-sensitive medical
items.
EE)
Chlorhexidine
is a member of the biguanides.
is extensively used in antiseptics.
is ineffective against vegetative bacteria.
is limited in use due to its high toxicity.
is a member of the biguanides AND is extensively used in
antiseptics.
FF)
Ethylene oxide is gas that
is very useful for sterilizing heat or moisture sensitive
items.
is potentially carcinogenic.
is used as a 37% aqueous solution.
is effective against all microorganisms except endospores and
viruses.
is very useful for sterilizing heat or moisture sensitive items
AND is potentially carcinogenic.
GG)
Which is true of iodine?
It does not readily kill endospores.
It may be used as an antiseptic or as a disinfectant.
It is important to use it at the recommended dilution.
It is usually found as tinctures or iodophors.
All of the choices are true.
HH)
Which of the following is true of hydrogen peroxide?
It is a sterilant for inanimate objects and is quickly
inactivated on living tissue.
It leaves a toxic residue.
It is broken down by catalase into water and oxygen.
It is even more effective when used in combination with
peracetic acid.
It is a sterilant for inanimate objects and is quickly
inactivated on living tissue; it is broken down by catalase into
water and oxygen AND it is even more effective when used in
combination with peracetic acid.
II)
Phenolics
denature proteins and destroy cytoplasmic membranes.
remain effective in the presence of detergents or organic
material.
such as triclosan, have been used widely in various lotions and
soaps.
reliably inactivate all groups of viruses.
denature proteins and destroy cytoplasmic membranes, remain
effective in the presence of detergents or organic material, AND
phenolics such as triclosan, have been used widely in various
lotions and soaps.
JJ)
Quaternary ammonium compounds are
cationic detergents which help wash surfaces.
attracted to the negative charge on the microbial cell
surface.
used as a 37% aqueous solution.
very effective against Pseudomonas.
cationic detergents which help wash surfaces AND attracted to
the negative charge on the microbial cell surface.
KK)
Silver sulfadiazine, a combination of silver and a sulfa drug,
is used to
disinfect water for drinking.
prevent infection of surgical wounds.
prevent infection of second- and third-degree burns.
counteract lead poisoning.
treat bites from werewolves.
LL)
Prions and viroids are easily destroyed by common sterilization
procedures.
True
False
MM)
Upon heat treatment, bacteria die at a constant proportion.
True
False
NN)
The more bacteria one starts with, the longer it will take to
kill them all.
True
False
OO)
Heat treatment is an effective method for sterilization or
disinfection of all materials.
True
False
PP)
Boiling is very effective at removing most common waterborne
pathogens.
True
False
QQ)
Dry heat takes a much shorter time to sterilize material than
wet heat.
True
False
RR)
Hydrogen peroxide may be used as a sterilant on living
tissue.
True
False
SS)
Organic acids, such as benzoic acid, are often added to foods to
prevent microbial growth.
True
False
TT)
Which of the following organisms are resistant to destruction by
typical control methods?
endospores
of Bacillus and Clostridium
Pseudomonas
naked viruses
Mycobacterium spp.
All of the choices are correct.
UU)
A common environmental organism that may even grow in certain
chemical disinfectants is
Escherichia coli.
Streptococcus pneumoniae.
Pseudomonas aeruginosa.
enveloped virus.
VV)
Upon treatment with heat or chemicals, bacteria will
all die immediately.
die at a constant proportion.
die at an exponential rate.
die at a geometric rate.
