Deck 11: Microbial Growth and Control

Question 1

Pathogenic microorganisms belong to which of the following categories?

A) Photoheterotrophs
B) Photoautotrophs
C) Chemoheterotrophs
D) Chemoautotrophs

Answer 1

C

Question 2

Microorganisms that obtain their energy from light and obtain the carbon they need to build macromolecules from CO₂ are ________.

A) photoheterotrophs
B) photoautotrophs
C) chemoheterotrophs
D) chemoautotrophs

Answer 2

B

Question 3

Microorganisms that obtain their energy from inorganic molecules and obtain the carbon they need to build macromolecules from CO₂ are ________.

A) photoheterotrophs
B) photoautotrophs
C) chemoheterotrophs
D) chemoautotrophs

Answer 3

D

Question 4

Microorganisms that obtain their energy from light and obtain the carbon they need to build macromolecules from organic molecules are ________.

A) photoheterotrophs
B) photoautotrophs
C) chemoheterotrophs
D) chemoautotrophs

Question 5

Microbial growth either in a natural environment or in a laboratory requires these physical requirements be within minimum and maximum ranges. (Select all that apply)

A) pH
B) Temperature
C) Osmolarity
D) Gravity

Question 6

Most microbes grow fastest in a pH range of ________.

A) 3.0 to 8.0
B) 6.5 to 7.5
C) 5.5 to 8.5
D) 6.5 to 8.5

Question 7

Which of the following cellular processes produces acidic products that will preserve food?

A) Fermentation
B) Aerobic respiration
C) Anaerobic respiration
D) Glycolysis

Question 8

Which of the following microorganism types has an optimum growth pH of 5 to 6?

A) Fungi
B) Protozoa
C) Viruses
D) Algae
E) Bacteria

Question 9

Optimum growth rate is above 80ᵒC for ________.

A) psychrophiles
B) mesophiles
C) thermophiles
D) hyperthermophiles

Question 10

Optimum growth rate is between 50ᵒC and 80ᵒC for ________.

A) psychrophiles
B) mesophiles
C) thermophiles
D) hyperthermophiles

Question 11

A psychrophilehas an optimum growth rate ________.

A) above 80ᵒC
B) between 15 and 30ᵒC
C) below 15ᵒC
D) between 50ᵒC and 80ᵒC

Question 12

A mesophile has an optimum growth rate ________.

A) above 80ᵒC
B) between 15 and 50ᵒC
C) below 15ᵒC
D) between 50ᵒC and 80ᵒC

Question 13

The point marked "y" on the plot of the growth rate of a culture of E. coli grown in Luria broth in a shaking water bath at various temperatures indicates ________ over the temperature range shown. (Select all that apply)

A) the maximum growth rate
B) the maximum temperature of growth
C) the optimum temperature of growth
D) the minimum temperature of growth

Question 14

The bracket marked "w" is the range of temperature where ________ bacteria have their optimum growth temperature.

A) hyperthermophilic
B) thermophilic
C) mesophilic
D) psychrophilic

Question 15

The bracket marked "x" is the range of temperature where ________ bacteria have their optimum growth temperature.

A) hyperthermophilic
B) thermophilic
C) mesophilic
D) psychrophilic

Question 16

The bracket marked "y" is the range of temperature where ________ bacteria have their optimum growth temperature.

A) hyperthermophilic
B) thermophilic
C) mesophilic
D) psychrophilic

Question 17

The bracket marked "z" is the range of temperature where ________ bacteria have their optimum growth temperature.

A) hyperthermophilic
B) thermophilic
C) mesophilic
D) psychrophilic

Question 18

Which of the following cell types cannot protect itself from lysis when placed in a hypotonic environment?

A) Animal cells
B) Bacterial cells
C) Fungal cells
D) Protozoan cells

Question 19

In a hypertonic environment, which way will water flow via osmosis?

A) Into the cell
B) Out of the cell
C) Neither since movement of water particles in and out of the cell will be equal
D) Neither because there will be no movement of water into or out of the cell

Question 20

In a hypotonic environment, which way will water flow via osmosis?

A) Into the cell
B) Out of the cell
C) Neither since movement of water particles in and out of the cell will be equal
D) Neither because there will be no movement of water into or out of the cell

Question 21

In an isotonic environment, which way will water flow via osmosis?

A) Into the cell
B) Out of the cell
C) Neither since movement of water particles in and out of the cell will be equal
D) Neither because there will be no movement of water into or out of the cell

Question 22

Carbon is ________. (Select all that apply)

A) the backbone for all organic macromolecules
B) acquired by photosynthetic organisms in a process called carbon fixation
C) acquired by chemoautotrophs in a process called carbon fixation
D) acquired by chemoheterotrophs from the intake of other organic molecules

Question 23

Examples of the enzymes that neutralize the damaging effects of superoxide free radicals are ________.

A) superoxide dismutase and beta-galactosidase
B) catalase and amylase
C) superoxide dismutase and catalase
D) superoxide dismutase, catalase and beta-galactosidase

Question 24

An obligate aerobe ________.

A) may use either fermentation or aerobic respiration
B) can only grow in anaerobic conditions
C) must have oxygen for aerobic respiration
D) uses fermentation but is not harmed by presence of oxygen

Question 25

A(n) ________ can only grow in anaerobic conditions.

A) obligate aerobe
B) facultative anaerobe
C) aerotolerant anaerobe
D) obligate anaerobe

Question 26

A(n) ________ uses fermentation pathways only but is not harmed by presence of oxygen.

A) facultative anaerobe
B) aerotolerant anaerobe
C) microaerophile
D) obligate anaerobe

Question 27

The illustration below depicts the growth of bacteria in nutrient agar tubes after stabbing an inoculum of bacteria through the center of the medium to the bottom of the tube. Tube "v" represents the growth of ________.

A) obligate aerobes
B) microaerophiles
C) facultative anaerobes
D) aerotolerant anaerobes

Question 28

The illustration below depicts the growth of bacteria in nutrient agar tubes after stabbing an inoculum of bacteria through the center of the medium to the bottom of the tube. Tube "W" represents the growth of ________.

A) obligate aerobes
B) facultative anaerobes
C) aerotolerant anaerobes
D) microaerophiles

Question 29

The illustration below depicts the growth of bacteria in nutrient agar tubes after stabbing an inoculum of bacteria through the center of the medium to the bottom of the tube. Tube "x" represents the growth of ________.

A) obligate anaerobes
B) obligate aerobes
C) facultative anaerobes
D) aerotolerant anaerobes

Question 30

The illustration below depicts the growth of bacteria in nutrient agar tubes after stabbing an inoculum of bacteria through the center of the medium to the bottom of the tube. Tube "y" represents the growth of ________.

A) obligate aerobes
B) obligate anaerobes
C) facultative anaerobes
D) aerotolerant anaerobes

Question 31

The illustration below depicts the growth of bacteria in nutrient agar tubes after stabbing an inoculum of bacteria through the center of the medium to the bottom of the tube. Tube "z" represents the growth of ________.

A) obligate aerobes
B) obligate anaerobes
C) facultative anaerobes
D) aerotolerant anaerobes

Question 32

Although classified as a micronutrient, the iron ion Fe³⁺ is a key metallic ion in the Electron Transport Chain of aerobic respiration. Which of the following statements concerning Fe³⁺ is true? (Select all that apply)

A) The low solubility of Fe³⁺ makes it difficult to obtain.
B) Siderophores are molecules that acquire iron from other chemical complexes.
C) Pathogenic bacteria obtain Fe³⁺ from host cells using siderophores.
D) Host cells themselves produce iron-binding proteins that have a lower affinity for Fe³⁺ than do the bacterial siderophores, thus preventing bacterial acquisition.

Question 33

When we look at the ion and micronutrients required for microbial growth, which of these statements is true? (Select all that apply)

A) Phosphorus is required for production of ATP and nucleic acids.
B) Sulfur is required for several amino acids found in proteins.
C) Potassium, sodium and chloride help maintain osmotic conditions inside the cell when external changes take place in the environment.
D) Nitrogen is required for the synthesis of fatty acids.

Question 34

Bacterial cell division requires ________. (Select all that apply)

A) replication of the chromosome
B) partitioning of the daughter chromosomes
C) the division of the two cells
D) formation of a spindle apparatus

Question 35

What does a bacterium have to do before cell division can take place? (Select all that apply)

A) Replicate ~5,000,000 base pairs
B) Synthesize peptidoglycan for new cell walls
C) Produce or collect basic materials needed for cellular metabolism
D) Produce microtubules to be used during cytokinesis

Question 36

Where does the ring of contractile proteins form in the cell undergoing binary fission?

A) At the origin of replication site.
B) At the termination of replication site.
C) In the center of the cell after replication of the chromosome is complete.
D) After the septum formation.

Question 37

Which of the following statements is descriptive of bacterial binary fission? (Select all that apply)

A) DNA replication begins at the origin site.
B) The origin site attaches to proteins from the cytoskeleton and are moved to opposite sides of the cell.
C) Formation of a ring of contractile proteins is inhibited by the presence of the nucleoids.
D) The contractile ring moves the two nucleiodsto the polar ends of the dividing cell.

Question 38

How does the exponential growth of bacterial cells affect their genetic diversity?

A) The greater the number of cells, the greater the expected number of spontaneous mutations.
B) It does not affect genetic diversity because binary fission is an asexual means of reproduction.
C) Spontaneous mutations are repaired by enzymatic repair mechanisms and therefore do not last long enough to cause a mutation.
D) Most spontaneous mutations are lethal therefore the mutated cells would die out and not reproduce.

Question 39

The cell density of an exponentially growing culture of E. coli as a function of time is shown below. The slope of the line marked x is ________.

A) (log 2)/τ
B) (log 2)/t
C) 40 min
D) t/(log 2)

Question 40

The cell density of an exponentially growing culture of E. coli as a function of time is shown below. The equation that describes the red line is ________.

A) N_t = N₀(2^σ)
B) N₀ = N_t(log 2)/t
C) N₀/N_t = 2^σ
D) N_t = N₀ + (log 2)(t/σ)

Question 41

The key characteristic of lag phase is ________.

A) the metabolic activities of cells change as they adapt to a new environment
B) the rate of cell growth is equal to the rate of cell death
C) the number of cells decline but not at a constant rate
D) the number of cells are increasing exponentially

Question 42

The key characteristic of log phase is ________.

A) the metabolic activities of cells change as they adapt to a new environment
B) the rate of cell growth is equal to the rate of cell death
C) the number of cells decline but not at a constant rate
D) the number of cells are increasing exponentially

Question 43

________ is the phase of bacterial cell growth where cell numbers decline but not at a constant rate.

A) Lag Phase
B) Log Phase
C) Stationary Phase
D) Death Phase

Question 44

Region 1 of the growth curve of bacteria shown in the illustration below depicts the ________ of growth.

A) log phase
B) stationary phase
C) lag phase
D) death phase

Question 45

Region 2 of the growth curve of bacteria shown in the illustration below depicts the ________ of growth.

A) log phase
B) stationary phase
C) lag phase
D) death phase

Question 46

Region 3 of the growth curve of bacteria shown in the illustration below depicts the ________ of growth.

A) log phase
B) stationary phase
C) lag phase
D) death phase

Question 47

Region 4 of the growth curve of bacteria shown in the illustration below depicts the ________ of growth.

A) log phase
B) stationary phase
C) lag phase
D) death phase

Question 48

Microbial cell density may be determined using ________. (Select all that apply)

A) a Petroff-Hausser chamber
B) spectrophotometry
C) dilution Plating
D) streak Plating

Question 49

________ uses either the spread plate or pour plate method.

A) Petroff-Hausser chamber
B) Spectrophotometry
C) Dilution Plating
D) Filtration

Question 50

________ concentrates low numbers of bacteria before plating.

A) Petroff-Hausser chamber
B) Spectrophotometry
C) Dilution Plating
D) Filtration

Question 51

A Petroff-Hausser chamber ________.

A) uses either the spread plate or pour plate method
B) concentrates low numbers of bacteria before plating
C) is used for the rapid determination of cell number by using the apparent absorbance of light
D) determines the number of cells/ml counted from known volume of fluid

Question 52

Spectrophotometry ________.

A) uses either the spread plate or pour plate method
B) concentrates low numbers of bacteria before plating
C) is used for the rapid determination of cell number by using the apparent absorbance of light
D) determines the number of cells/ml counted from an unknown volume of fluid pipetted

Question 53

Which of the following methods of measuring cell density would be the best to choose when you know that you do not have a lot of bacteria present in your sample?

A) A Petroff-Hausser chamber because you are visually counting bacteria.
B) Spectrophotometry because it is sensitive to low bacterial numbers.
C) Dilution plating because you will be able to count between 30-300 cells on a plate.
D) Filtration because the number of bacteria may be concentrated on the filter prior to plating.

Question 54

Which of the following methods of measuring cell density cannot distinguish between living and dead bacterial cells and thus may not provide the data needed in an actual infection or contamination? (Select all that apply)

A) Spectrophotometry
B) A Petroff-Hausser chamber
C) Dilution Plating
D) Filtration

Question 55

If the volume of growth medium trapped under the double-lined box shown in the magnification of the Petroff-Hausser chamber is 5 × 10^-5mls, the density of cells in the culture is ________.

A) approximately 2 × 10⁵
B) approximately 2 × 10⁶
C) approximately 2 × 10¹⁰
D) approximately 2 × 10²⁵

Question 56

Percent transmittance is equal to ________.

A) I_t/I₀
B) log(I_t/I₀)
C) log(I₀/I_t)
D) I_o/I_t

Question 57

Absorbance is equal to ________.

A) I_t/I₀
B) log(I_t/I₀)
C) log(I₀/I_t)
D) -log(I_t/I₀)

Question 58

The viable cell count (cells/ml) from the spread plate method shown below is ________.

A) 2.1 × 10³
B) 2.1 × 10⁴
C) 2.1 × 10⁵
D) 2.1 × 10⁶

Question 59

The viable cell count (cells/ml) from the pour plate method shown below is ________.

A) 2.5 × 10³
B) 2.5 × 10⁴
C) 2.5 × 10⁵
D) 2.5 × 10⁶

Question 60

Which of these is a correct match? (Select all that apply)

A) Growth medium: an artificial liquid or gel containing nutrients designed to meet the microbes' specific growth requirements.
B) Inoculum: a small sample of microorganisms which are placed into a growth medium to produce a culture.
C) Colony: a visible mass of cells descended from a single cell.
D) Pure culture: all the cells descended from single ancestor cell.

Question 61

The streak plate method ________. (Select all that apply)

A) is used to separate microbes found in a mixed sample into individual colony forming units
B) is used to obtain pure cultures of bacteria and fungi
C) works better with low concentrations of microbes
D) uses a series of dilutions of a high concentration of a mixed population of microbes before plating so that 30-300 cells grow on a plate

Question 62

How can growth medium be classified? (Select all that apply)

A) According to its physical properties.
B) According to its chemical properties.
C) As selective growth media.
D) As differential growth media.

Question 63

Which of the following statements are true concerning chemically defined media? (Select all that apply)

A) In chemically defined media all concentrations of every ingredient are known.
B) Chemically defined media contain defined amounts of carbon and energy sources.
C) In chemically defined media a buffer is used to maintain an appropriate pH.
D) In a chemically defined media salts are added to maintain osmotic balance.

Question 64

A growth medium in which the exact chemical concentrations are unknown is termed ________.

A) complex medium
B) enriched medium
C) selective medium
D) differential medium

Question 65

Complex media ________.

A) enhance the growth of one group of microbes
B) inhibit the growth of unwanted bacteria
C) distinguish between two different types of bacteria
D) is media where the exact chemical concentrations are unknown

Question 66

Selective media ________.

A) enhance the growth of one group of microbes
B) inhibit the growth of unwanted bacteria
C) distinguish between two different types of bacteria
D) is media where the exact chemical concentrations are known

Question 67

________ media distinguish between two different types of bacteria.

A) Complex
B) Enriched
C) Selective
D) Differential

Question 68

An enriched medium ________.

A) enhances the growth of one group of microbes
B) inhibits the growth of unwanted bacteria
C) distinguishes between two different types of bacteria
D) is when the exact chemical concentrations are known

Question 69

The selective media modified Thayer-Martin is used for identifying ________.

A) Streptococcus pyogenes
B) Neiserria gonorrheae
C) Escherichia coli
D) Salmonella species

Question 70

Blood agar differentiates ________ like Streptococcus pyogenes from most other bacteria.

A) alpha-hemolytic colonies
B) beta-hemolytic colonies
C) gamma-hemolytic colonies
D) delta-hemolytic colonies

Question 71

MacConkey agar is selective in that it inhibits Gram-positive bacterial growth and differential in that it distinguishes ________ from other coliforms that are unable to ferment lactose.

A) Staphylococcus aureus
B) Salmonella
C) Shigella dystenteriae
D) Escherichia coli

Question 72

An example of a bacterial species that shows the growth pattern seen below is ________.

A) Streptococcus pyogenes
B) Streptococcus pneumoniae
C) E. coli
D) Salmonella

Question 73

An example of a bacterial species that shows the growth pattern seen below is ________.

A) Streptococcus pyogenes
B) Streptococcus pneumoniae
C) E. coli
D) Salmonella

Question 74

An example of a bacterial species that shows the growth pattern seen below is ________.

A) Streptococcus pyogenes
B) Streptococcus pneumoniae
C) E. coli
D) Salmonella

Question 75

An example of a bacterial species that shows the growth pattern seen below is ________.

A) Streptococcus pyogenes
B) Streptococcus pneumoniae
C) E. coli
D) Salmonella

Question 76

________ is(are) a complex biofilm of bacteria that stick to your teeth.

A) Dental caries
B) Plaque
C) Adhesions
D) The dental matrix

Question 77

Members of the microbial communities that form bacterial biofilms show ________ because of their ability to both cause diseases and their enhanced resistance to relatively high concentrations of antibacterial agents.

A) antagonism
B) commensalism
C) mutualism
D) parasitism

Question 78

Biofilms ________. (Select all that apply)

A) are a complex community of microorganisms that adhere to a solid surface via a matrix
B) may have one organism's waste products serving as a primary nutrient for another microbe
C) have aerobic microorganisms living near the top of the biofilm that use enough of the oxygen to make the lower layers either microaerophilic or anaerobic
D) are formed by all different species of bacteria

Question 79

What services does a clinical microbiology lab provide physicians and their patients? (Select all that apply)

A) To determine if the patient's illness is caused by a microbe.
B) To identify pathogenic microbes that may be causing a patient's illness.
C) To determine the antibacterial susceptibility profile of a bacteria causing a patient's illness so therapy can be targeted.
D) To determine antiviral susceptibility to aid antibiotic therapy.

Question 80

Why are actual specimens preferred over swabs of a specimen? (Select all that apply)

A) Specimen swabs do not collect all microbes when used to take a patient specimen.
B) Specimen swabs only carry very small volumes of the specimen.
C) It is difficult to separate bacterial or fungal cells from a specimen swab's fibers in order to plate them or put them into a broth.
D) Swabs inhibit the growth of pathogens but allow the growth of normal microbiota.