A medium that contains yeast extract, glucose, and peptones would be a(n)
complex medium
selective medium
anaerobic medium
chemically defined medium
A bacterial suspension produces a turbidity reading that corresponds to 5 x 107 CFU/ml. A viable plate count of the same suspension produces a concentration of only 1 x 105 CFU/ml. You most correctly conclude that
you forgot to use the 500x multiplier that is always a part of computing viable counts.
turbidity is an indirect counting method and is inherently inaccurate.
most of the cells in the suspension are dead.
the suspension is safe to drink.
In metabolism, ______ reactions liberate energy used to make ATP, whereas ______ reactions require energy supplied by the hydrolysis of ATP.
anabolic, catabolic
catabolic, anabolic
biosynthetic, degradative
The ATP made by oxidative phosphorylation
is powered by chemiosmosis using a proton gradient.
is made at large transmembrane proteins called ATP synthases.
represents most of the energy made during respiration.
all of the above.
Why are both the temperatures and times involved in hot air sterilization higher than those involved in steam sterilization?
Heat transfer is more efficient when water is involved.
Desiccated organisms are harder to kill.
Microbes have more organic material to eat in ovens.
Microbes are hydrophobic.
At which phase of microbial growth is the growth rate identical to the death rate?
lag phase
death phase
stationary phase
log phase
A bacterial growth experiment began with 100 cells and ended with 409,600 cells. How many generations occurred?
3
6
24
12 [Log (409,600) - Log (100)]/log 2=12, See Appendix B
During Glycolysis
ATP is generated by substrate-level phosphorylation
carbon dioxide is produced.
oxygen is consumed.
Suppose you have a suspension of C. botulinum endospores that has a decimal reduction time (DRT) of 1.5 minutes at 121 °C. If you had 1 x 10 6 endospores, how long (at 121 °C ) would it take to reduce this number to a single organism?
12 minutes
3 minutes
9 minutes
6 minutes
The process of destroying vegetative pathogens on living tissue is most correctly called
disinfection.
sanitization.
sterilization.
antisepsis.
What type of organism would have an optimum growth temperature at about 12 °C?
psychrophile
psychrotroph
thermophile
mesophile
Plasmas, supercritical fluids, and peroxygens are all
obsolete microbial control methods.
new methods used to sterilize.
used to grow bacteria.
commonly used in surgeries.
The most important products of the Krebs cycle are
citric acid and pyruvic acid.
ATP and water.
NADH and FADH2.
carbon dioxide and water.
The method of preserving bacterial cultures that involves sublimation is
drying.
deep-freezing.
lyophilization.
refrigeration.
The germicidal action of chlorine is due to the formation of
hypochlorous acid.
sodium chloride.
free oxygen.
ozone.
The net yield of ATP equivalents from one turn of the Krebs cycle (starting with acetyl-CoA) is
12
36
The most common physical method of microbial control in foods is
heat treatment or low temperatures.
pressure.
radiation.
filtration.
The most resistant microbe (of the ones listed) to chemical biocides is
protozoan cysts.
mycobacteria.
bacterial endospores.
viruses without envelopes.
A bacterostatic agent
causes bacteria to grow.
kills bacteria using an electric charge.
kills bacteria.
inhibits the growth of bacteria.
Flavoproteins, cytochromes, and ubiquinones are all part of
the electron transport chain.
the pentose phosphate pathway
glycolysis.
the Krebs cycle.
Phenolics, biguanides, halogens, alcohols, and probably quaternary ammonium compounds (Quats) all cause damage to the cell’s
wall
nucleic acids
capsule
plasma membrane
Radiation does most of its lethal damage by causing breaks in, or changes to the microbe’s
plasma membrane.
cell wall
DNA
flagella
Which of the following is not a common end product of a microbial fermentation?
ethyl alcohol
lactic acid
glucose
CO2
Organisms that grow deep in the bottom of the ocean (no light) next to hydrogen sulfide vents (source of energy), and are able to fix CO2 in the seawater, would be referred to as
photoheterotrophs.
photoautotrophs.
chemoautotrophs.
chemoheterotrophs.
Which type of organism is indifferent to either the presence or absence of oxygen?
mircoaerophile
obligate anaerobe
facultative anaerobe
aerotolerant anaerobe
During photosynthesis, the main products of the light-dependent reactions are ________, whereas the main products of light-independent reactions are __________.
chlorophyll/NADPH and O2
lipids/proteins
sugars/ATP and water
ATP, O2, and NADPH/sugars
Enzymes
raise the temperature of a chemical reaction.
are permanently altered by a chemical reaction.
lower the activation energy of a chemical reaction.
lower the energy difference between the reactants and products.
Five bacterial cells with a generation time of 15 minutes were allowed to grow for 8 hours. How many cells are present?
5 million
3.20 × 108
4.29 × 109
2.15 × 1010
A sample of milk is diluted 1:2,000,000 and 1 ml samples of this dilution are plated in duplicate. The average plate count is 50 CFU. How many CFU/ml are present in the undiluted milk?
50,000,000
100,000,000
10,000,000
500,000,000
Blood agar containing an antibiotic that inhibits gram-positive organisms, would most correctly be called
selective.
anaerobic.
both selective and differential
differential
