2697935
Descripción
Test por elizabeth.merner, actualizado hace más de 1 año
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Creado por elizabeth.merner
hace más de 9 años
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Pregunta 1
Pregunta
A medium that contains yeast extract, glucose, and peptones would be a(n)
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complex medium
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selective medium
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anaerobic medium
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chemically defined medium
Pregunta 2
Pregunta
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
Respuesta
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you forgot to use the 500x multiplier that is always a part of computing viable counts.
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turbidity is an indirect counting method and is inherently inaccurate.
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most of the cells in the suspension are dead.
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the suspension is safe to drink.
Pregunta 3
Pregunta
In metabolism, ______ reactions liberate energy used to make ATP, whereas ______ reactions require energy supplied by the hydrolysis of ATP.
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anabolic, catabolic
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catabolic, anabolic
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biosynthetic, degradative
Pregunta 4
Pregunta
The ATP made by oxidative phosphorylation
Respuesta
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is powered by chemiosmosis using a proton gradient.
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is made at large transmembrane proteins called ATP synthases.
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represents most of the energy made during respiration.
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all of the above.
Pregunta 5
Pregunta
Why are both the temperatures and times involved in hot air sterilization higher than those involved in steam sterilization?
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Heat transfer is more efficient when water is involved.
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Desiccated organisms are harder to kill.
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Microbes have more organic material to eat in ovens.
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Microbes are hydrophobic.
Pregunta 6
Pregunta
At which phase of microbial growth is the growth rate identical to the death rate?
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lag phase
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death phase
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stationary phase
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log phase
Pregunta 7
Pregunta
A bacterial growth experiment began with 100 cells and ended with 409,600 cells. How many generations occurred?
Respuesta
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3
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6
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24
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12 [Log (409,600) - Log (100)]/log 2=12, See Appendix B
Pregunta 8
Pregunta
During Glycolysis
Respuesta
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ATP is generated by substrate-level phosphorylation
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carbon dioxide is produced.
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oxygen is consumed.
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all of the above.
Pregunta 9
Pregunta
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?
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12 minutes
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3 minutes
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9 minutes
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6 minutes
Pregunta 10
Pregunta
The process of destroying vegetative pathogens on living tissue is most correctly called
Respuesta
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disinfection.
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sanitization.
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sterilization.
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antisepsis.
Pregunta 11
Pregunta
What type of organism would have an optimum growth temperature at about 12 °C?
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psychrophile
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psychrotroph
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thermophile
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mesophile
Pregunta 12
Pregunta
Plasmas, supercritical fluids, and peroxygens are all
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obsolete microbial control methods.
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new methods used to sterilize.
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used to grow bacteria.
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commonly used in surgeries.
Pregunta 13
Pregunta
The most important products of the Krebs cycle are
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citric acid and pyruvic acid.
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ATP and water.
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NADH and FADH2.
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carbon dioxide and water.
Pregunta 14
Pregunta
The method of preserving bacterial cultures that involves sublimation is
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drying.
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deep-freezing.
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lyophilization.
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refrigeration.
Pregunta 15
Pregunta
The germicidal action of chlorine is due to the formation of
Respuesta
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hypochlorous acid.
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sodium chloride.
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free oxygen.
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ozone.
Pregunta 16
Pregunta
The net yield of ATP equivalents from one turn of the Krebs cycle (starting with acetyl-CoA) is
Respuesta
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12
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36
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24
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6
Pregunta 17
Pregunta
The most common physical method of microbial control in foods is
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heat treatment or low temperatures.
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pressure.
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radiation.
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filtration.
Pregunta 18
Pregunta
The most resistant microbe (of the ones listed) to chemical biocides is
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protozoan cysts.
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mycobacteria.
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bacterial endospores.
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viruses without envelopes.
Pregunta 19
Pregunta
A bacterostatic agent
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causes bacteria to grow.
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kills bacteria using an electric charge.
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kills bacteria.
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inhibits the growth of bacteria.
Pregunta 20
Pregunta
Flavoproteins, cytochromes, and ubiquinones are all part of
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the electron transport chain.
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the pentose phosphate pathway
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glycolysis.
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the Krebs cycle.
Pregunta 21
Pregunta
Phenolics, biguanides, halogens, alcohols, and probably quaternary ammonium compounds (Quats) all cause damage to the cell’s
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wall
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nucleic acids
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capsule
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plasma membrane
Pregunta 22
Pregunta
Radiation does most of its lethal damage by causing breaks in, or changes to the microbe’s
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plasma membrane.
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cell wall
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DNA
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flagella
Pregunta 23
Pregunta
Which of the following is not a common end product of a microbial fermentation?
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ethyl alcohol
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lactic acid
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glucose
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CO2
Pregunta 24
Pregunta
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
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photoheterotrophs.
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photoautotrophs.
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chemoautotrophs.
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chemoheterotrophs.
Pregunta 25
Pregunta
Which type of organism is indifferent to either the presence or absence of oxygen?
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mircoaerophile
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obligate anaerobe
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facultative anaerobe
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aerotolerant anaerobe
Pregunta 26
Pregunta
During photosynthesis, the main products of the light-dependent reactions are ________, whereas the main products of light-independent reactions are __________.
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chlorophyll/NADPH and O2
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lipids/proteins
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sugars/ATP and water
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ATP, O2, and NADPH/sugars
Pregunta 27
Pregunta
Enzymes
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raise the temperature of a chemical reaction.
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are permanently altered by a chemical reaction.
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lower the activation energy of a chemical reaction.
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lower the energy difference between the reactants and products.
Pregunta 28
Pregunta
Five bacterial cells with a generation time of 15 minutes were allowed to grow for 8 hours. How many cells are present?
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5 million
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3.20 × 108
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4.29 × 109
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2.15 × 1010
Pregunta 29
Pregunta
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?
Respuesta
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50,000,000
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100,000,000
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10,000,000
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500,000,000
Pregunta 30
Pregunta
Blood agar containing an antibiotic that inhibits gram-positive organisms, would most correctly be called
Respuesta
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selective.
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anaerobic.
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both selective and differential
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differential
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