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Speedback Assignment 2

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Chapter 5 - Microbial Metabolism Chapter 6 - Microbial Growth Chapter 7 - The Control of Microbial Growth
elizabeth.merner
Quiz by elizabeth.merner, updated more than 1 year ago
elizabeth.merner
Created by elizabeth.merner over 9 years ago
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Question 1

Question
A medium that contains yeast extract, glucose, and peptones would be a(n)
Answer
  • complex medium
  • selective medium
  • anaerobic medium
  • chemically defined medium

Question 2

Question
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
Answer
  • 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.

Question 3

Question
In metabolism, ______ reactions liberate energy used to make ATP, whereas ______ reactions require energy supplied by the hydrolysis of ATP.
Answer
  • anabolic, catabolic
  • catabolic, anabolic
  • biosynthetic, degradative

Question 4

Question
The ATP made by oxidative phosphorylation
Answer
  • 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.

Question 5

Question
Why are both the temperatures and times involved in hot air sterilization higher than those involved in steam sterilization?
Answer
  • 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.

Question 6

Question
At which phase of microbial growth is the growth rate identical to the death rate?
Answer
  • lag phase
  • death phase
  • stationary phase
  • log phase

Question 7

Question
A bacterial growth experiment began with 100 cells and ended with 409,600 cells. How many generations occurred?
Answer
  • 3
  • 6
  • 24
  • 12 [Log (409,600) - Log (100)]/log 2=12, See Appendix B

Question 8

Question
During Glycolysis
Answer
  • ATP is generated by substrate-level phosphorylation
  • carbon dioxide is produced.
  • oxygen is consumed.
  • all of the above.

Question 9

Question
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?
Answer
  • 12 minutes
  • 3 minutes
  • 9 minutes
  • 6 minutes

Question 10

Question
The process of destroying vegetative pathogens on living tissue is most correctly called
Answer
  • disinfection.
  • sanitization.
  • sterilization.
  • antisepsis.

Question 11

Question
What type of organism would have an optimum growth temperature at about 12 °C?
Answer
  • psychrophile
  • psychrotroph
  • thermophile
  • mesophile

Question 12

Question
Plasmas, supercritical fluids, and peroxygens are all
Answer
  • obsolete microbial control methods.
  • new methods used to sterilize.
  • used to grow bacteria.
  • commonly used in surgeries.

Question 13

Question
The most important products of the Krebs cycle are
Answer
  • citric acid and pyruvic acid.
  • ATP and water.
  • NADH and FADH2.
  • carbon dioxide and water.

Question 14

Question
The method of preserving bacterial cultures that involves sublimation is
Answer
  • drying.
  • deep-freezing.
  • lyophilization.
  • refrigeration.

Question 15

Question
The germicidal action of chlorine is due to the formation of
Answer
  • hypochlorous acid.
  • sodium chloride.
  • free oxygen.
  • ozone.

Question 16

Question
The net yield of ATP equivalents from one turn of the Krebs cycle (starting with acetyl-CoA) is
Answer
  • 12
  • 36
  • 24
  • 6

Question 17

Question
The most common physical method of microbial control in foods is
Answer
  • heat treatment or low temperatures.
  • pressure.
  • radiation.
  • filtration.

Question 18

Question
The most resistant microbe (of the ones listed) to chemical biocides is
Answer
  • protozoan cysts.
  • mycobacteria.
  • bacterial endospores.
  • viruses without envelopes.

Question 19

Question
A bacterostatic agent
Answer
  • causes bacteria to grow.
  • kills bacteria using an electric charge.
  • kills bacteria.
  • inhibits the growth of bacteria.

Question 20

Question
Flavoproteins, cytochromes, and ubiquinones are all part of
Answer
  • the electron transport chain.
  • the pentose phosphate pathway
  • glycolysis.
  • the Krebs cycle.

Question 21

Question
Phenolics, biguanides, halogens, alcohols, and probably quaternary ammonium compounds (Quats) all cause damage to the cell’s
Answer
  • wall
  • nucleic acids
  • capsule
  • plasma membrane

Question 22

Question
Radiation does most of its lethal damage by causing breaks in, or changes to the microbe’s
Answer
  • plasma membrane.
  • cell wall
  • DNA
  • flagella

Question 23

Question
Which of the following is not a common end product of a microbial fermentation?
Answer
  • ethyl alcohol
  • lactic acid
  • glucose
  • CO2

Question 24

Question
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
Answer
  • photoheterotrophs.
  • photoautotrophs.
  • chemoautotrophs.
  • chemoheterotrophs.

Question 25

Question
Which type of organism is indifferent to either the presence or absence of oxygen?
Answer
  • mircoaerophile
  • obligate anaerobe
  • facultative anaerobe
  • aerotolerant anaerobe

Question 26

Question
During photosynthesis, the main products of the light-dependent reactions are ________, whereas the main products of light-independent reactions are __________.
Answer
  • chlorophyll/NADPH and O2
  • lipids/proteins
  • sugars/ATP and water
  • ATP, O2, and NADPH/sugars

Question 27

Question
Enzymes
Answer
  • 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.

Question 28

Question
Five bacterial cells with a generation time of 15 minutes were allowed to grow for 8 hours. How many cells are present?
Answer
  • 5 million
  • 3.20 × 108
  • 4.29 × 109
  • 2.15 × 1010

Question 29

Question
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?
Answer
  • 50,000,000
  • 100,000,000
  • 10,000,000
  • 500,000,000

Question 30

Question
Blood agar containing an antibiotic that inhibits gram-positive organisms, would most correctly be called
Answer
  • selective.
  • anaerobic.
  • both selective and differential
  • differential
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