Deck 6: Cultivating Microorganisms

Question 1

A nutrient medium which is a liquid broth has agar added to it.How is its nutritional composition altered?

A)Additional ions are now present affecting the osmotic strength
B)New carbon sources for catabolism are now added
C)New carbon sources for anabolism have been added
D)All responses are correct
E)None of the responses are correct

Answer 1

E

Question 2

Which organism provides the greatest challenge when making culture medium that we desire to be sterile?

A)mesophilic bacteria
B)thermophilic bacteria
C)endospores
D)viruses
E)fungi

Answer 2

C

Question 3

A lithotroph is defined as an organism that uses _____ as a source of _____.

A)inorganic compounds;electrons
B)organic compounds;energy and electrons
C)inorganic compounds;carbon
D)sunlight;energy
E)carbon dioxide;energy

Answer 3

A

Question 4

Term for microbes that grow optimally at very high salt concentrations.

A)osmolphiles
B)barophiles
C)halophiles
D)psychrophiles
E)thermophiles

Question 5

The "great plate count anomaly" refers to an observation that is analogous to that made when:

A)growing bacteria in solid versus liquid media
B)counting virions using direct and indirect methods
C)plating on enrichment and non-enrichment media
D)plating on differential and non-differential media
E)none is an equivalent scenario

Question 6

Enrichment media that contains starch as the sole carbon source is encouraging the growth of microbes that produce _____ .

A)glucose
B)the enzyme amylase
C)the enzyme cellulase
D)all twenty amino acids
E)all required vitamins

Question 7

What term applies to a microbe that can synthesize all of its cellular constituents from a simple carbon source and inorganic salts?

A)autotroph
B)heterotroph
C)auxotroph
D)prototroph
E)a chemotroph

Question 8

What must be added to M9 medium for an auxotrophic E.coli strain to be able to grow?

A)glucose
B)glucose plus nucleotides,amino acids and lipids
C)glucose plus at least one other organic component
D)glucose plus amino acids
E)the medium is sufficient

Question 9

What must be added to M9 medium for a prototrophic E.coli strain to be able to grow?

A)glucose
B)glucose plus nucleotides,amino acids and lipids
C)glucose plus at least one other organic component
D)glucose plus amino acids
E)the medium is sufficient

Question 10

A chemotroph is defined as an organism that uses _____ as a source of _____.

A)sunlight;energy
B)organic compounds;carbon
C)organic or inorganic compounds;energy
D)inorganic compounds;energy
E)carbon dioxide;carbon

Question 11

What is nitrogen fixation?

A)The oxidation of nitrate to ammonia for assimilation.
B)The oxidation of ammonia to nitrate for assimilation.
C)The reduction of dinitrogen to ammonia for assimilation.
D)The reduction of nitrate to dinitrogen for assimilation.
E)The release of an amino group from an amino acid for assimilation.

Question 12

Which one of the following elements is considered a microelement,usually required in minute amounts in microbiological media?

A)phosphate
B)potassium
C)iron
D)manganese
E)magnesium

Question 13

What is the term for microbes that grow optimally at a pH below 5.5?

A)alkalophiles
B)psychrophiles
C)halophiles
D)acidophiles
E)barophiles

Question 14

What must be added to LB medium for a prototrophic E.coli strain to be able to grow?

A)glucose
B)glucose plus nucleotides,amino acids and lipids
C)glucose plus at least one other organic component
D)glucose plus amino acids
E)the medium is sufficient

Question 15

What is the function of siderophores?

A)Transporting waste products out of the cell.
B)Binding iron for transport into the cell.
C)Binding glucose for transport into the cell.
D)Transporting proteins out of the cell.
E)Moving potassium into the cell for osmotic regulation.

Question 16

What is the most abundant form of nitrogen in the biosphere?

A)ammonia
B)nitrate
C)nitrite
D)dinitrogen
E)nitrous oxide

Question 17

What must be added to LB medium for an auxotrophic E.coli strain to be able to grow?

A)glucose
B)glucose plus nucleotides,amino acids and lipids
C)glucose plus at least one other organic component
D)glucose plus amino acids
E)the medium is sufficient

Question 18

The enzyme catalase is used to detoxify which harmful oxygen species?

A)hydroxyl radical
B)superoxide
C)hydrogen peroxide
D)ozone
E)singlet oxygen

Question 19

You identify a microbe that grows poorly under regular atmospheric conditions but well in animal tissues.What group does this microbe likely belong to?

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

Question 20

Which one of the following is NOT a physical factor that affects the growth rate of cells?

A)nutrient concentration
B)temperature
C)pressure
D)light intensity
E)radiation

Question 21

Which medium is used to obtain maximum yield of any pure culture?

A)enrichment
B)selective
C)differential
D)general purpose
E)all work equally well for this purpose

Question 22

Fresh media is inoculated with an actively growing Escherichia coli culture.You measure the optical density (OD)at the time of inoculation and record a value of 0.05)Two hours later you take another reading and record an optical density of 0.2)What is the generation time for your culture?

A)30 minutes
B)40 minutes
C)50 minutes
D)60 minutes
E)Cannot determine from the information given.

Question 23

Which medium will best favor distinguishing hemolytic and non-hemoltic Streptococci?

A)Enrichment/differential
B)Selective/differential
C)Enrichment/selective
D)general purpose
E)all work equally well for this purpose

Question 24

What is the mean growth rate for a culture that has a generation time of 1 hour?

A)1 hr.
B)2 hr.
C)1 hr⁻¹.
D)2 hr⁻¹.
E)Cannot determine from the information given.

Question 25

How long would it take a culture of E.coli with a starting cell density of 1 X 10⁵ cells/ ml to reach a cell density of 1 X 10⁸ cells/ml if it had a generation time of 30 minutes?

A)3 hours
B)4 hours
C)5 hours
D)6 hours
E)7 hours

Question 26

What would you use to measure the optical density of a bacterial culture?

A)a Petroff-Hauser counting chamber
B)a flow cytometer
C)the plate count method
D)a spectrophotometer
E)a microscope

Question 27

Which substance inhibits the growth of Gram positive bacteria?

A)bile salts
B)iron
C)red blood cells
D)lactose
E)glucose

Question 28

Which medium is used to allow some microbes on a plate to be distinguished from others?

A)enrichment
B)selective
C)differential
D)general purpose
E)all work equally well for this purpose

Question 29

In order for a chemostat to operate properly,what must the reservoir contain?

A)a complex medium
B)vitamins
C)all twenty amino acids
D)a limiting nutrient
E)oxygen

Question 30

Which medium is used to allow some microbes to grow while suppressing others?

A)enrichment
B)selective
C)differential
D)general purpose
E)all work equally well for this purpose

Question 31

In which phase of the growth curve does preparation for cell division and synthesis of enzymes needed for catabolic activity take place?

A)lag phase
B)exponential phase
C)stationary phase
D)death phase
E)all phases

Question 32

The plate count method was used to estimate the number of bacteria in a culture over time.Serial dilutions were made of culture samples at various time points.A 0.1 ml portion of the 10⁻⁶ dilution was spread over the surface of a nutrient agar plate for each time point.The plates were incubated for 24 hrs and the colony forming units (CFU)were counted on each plate.A total of 45 colonies were counted on the plate for the 30 minute time point.What was the cell population for this time point?

A)4)5 X 10⁴ CFU/ml
B)4)5 X 10⁵ CFU/ml
C)4)5 X 10⁶ CFU/ml
D)4)5 X 10⁷ CFU/ml
E)4)5 X 10⁸ CFU/ml

Question 33

Which method will distinguish live bacteria from total cells present

A)use of hemocytometer on culture media
B)spectrophotometry
C)plate dilution counts
D)use of a chemostat
E)none is suitable

Question 34

If a cell culture contains 400 cells/ml at time = 0 and it has a generation time of 30 minutes,how many cells (cells/ml)will be present after 2 hours of incubation?

A)1200 cells/ml
B)1600 cells/ml
C)2400 cells/ml
D)3200 cells/ml
E)6400 cells/ml

Question 35

During steady state growth in a chemostat,the growth rate of the cells is equivalent to:

A)the nutrient concentration.
B)the generation time.
C)the cell yield.
D)the flow rate.
E)the dilution rate.

Question 36

If you had an E.coli culture with a starting cell density of 1 X 10⁶ cells/ml and it had a generation time of 40 minutes,what would be the cell density after incubation for 6 hours?

A)3 X 10⁸ cells/ml
B)5)1 X 10⁸ cell/ml
C)6)3 X 10⁸ cells/ml
D)9)4 X 10⁸ cells/ml
E)1 X 10⁹ cells/ml

Question 37

Which medium is used to allow slow-growing microbes to gain a competitive growth advantage?

A)enrichment
B)selective
C)differential
D)general purpose
E)all work equally well for this purpose

Question 38

Which medium is considered both selective and differential?

A)MacConkey agar
B)Triple sugar iron agar
C)LB broth
D)M9 medium
E)Blood agar

Question 39

Which of these methods can be used to obtain a viable cell count?

A)counting chamber direct count
B)turbidity measurement
C)plate counts of serial dilutions
D)loop dilution
E)optical density

Question 40

What is a chemostat?

A)A system used for the continuous culture of microbial cells.
B)A chemical used as a substrate for growth of microbial cells.
C)The maximum growth rate that can be obtained for a useable substrate.
D)A batch culture that uses a defined medium for growth.
E)A nutrient that is able to control the growth rate of a bacterial culture.

Question 41

Many disinfectants are strong oxidizing agents and disrupt many cellular functions.Which of these is an example of an oxidizing agent?

A)isopropanol
B)carbolic acid
C)triclosan
D)chlorine bleach
E)phenol

Question 42

To eliminate all bacteria by filtration,what is the maximum pore size that will be effective?

A)0)45 um
B)0)2 um
C)0)1 um
D)0)05 um
E)0)01 um

Question 43

Alcohols like ethanol and isopropanol are commonly used as antiseptics because they are very effective at reducing the bacterial load.What is their mode of action?

A)disrupting the plasma membrane
B)inhibiting DNA replication
C)inhibiting protein synthesis
D)disruption of the peptidoglycan
E)inhibiting transcription

Question 44

To thrive on a selective medium,a microbe will usually possess: (Select all that apply)

A)Salt tolerance
B)Prototrophic capability
C)Anaerobic capability
D)Acid tolerance
E)Ability to metabolize an unusual nutrient

Question 45

Which of these methods is bacteriostatic?

A)Ultrafiltration
B)Use of gamma irradiation
C)Pasteurization
D)Dessication
E)Autoclaving

Question 46

Bacteria grow for 12 generations in 4 hours.What is the growth rate?

A)3 generations per hour
B)48 generations per hour
C)0)33 generations per hour
D)33 generations per hour
E)None is correct

Question 47

Which method listed below will result in sterilization of an environmental water sample?

A)Boiling the sample for ten minutes.
B)Adding bleach to the sample.
C)Heating to 212°C for 15 minutes
D)Heating the sample to 70°C for 30 minutes.
E)Microwaving the sample for 3 minutes.

Question 48

Which is the best definition of an antiseptic?

A)A chemical agent that is applied to hospital equipment to kill or inhibit microbes.
B)A chemical agent that is applied to living tissue to kill and inhibit microbes.
C)An antibiotic that is applied to living tissue.
D)A physical agent that is used to sterilize hospital equipment.
E)A physical agent that is used on human tissue to inhibit microbial growth.

Question 49

To eliminate all viruses by filtration,what is the maximum pore size that will be effective?

A)0)45 um
B)0)2 um
C)0)1 um
D)0)05 um
E)0)01 um

Question 50

You grow Lactobacillus,an aerotolerant anaerobe,for twelve hours in two identical glucose-conntaining flasks under aerobic conditions (Flask A)and anaerobic conditions (Flask B).Select the correct statements.(Select all that apply)

A)Flask A will grow faster
B)Flask B will have a higher pH
C)Flask A will produce more ATP
D)Flask B will have a higher biomass
E)None is a correct statement

Question 51

The least durable filter of infectious agents is one made of:

A)Teflon
B)Cellulose acetate
C)Nylon
D)Polytetrafluoroethylene
E)All are equally durable

Question 52

Why is colony morphology not considered reliable for species identification? (Select all that apply)

A)Species may respond differently on different nutritional formulations in media
B)Colony size can differ on a single plate depending upon proximity of the cells applied
C)Mutations may affect uniformity of colony appearances
D)Agar can differ in nutrient composition in different areas within a culture dish
E)Agar formulations vary from one batch to another

Question 53

Which of these methods will ensure sterility?

A)Refrigeration
B)Freezing
C)Pasteurization
D)Dessication
E)Autoclaving

Question 54

You grow Clostridium tetani,an obligate anaerobe,for twelve hours in two identical glucose-containing flasks under aerobic conditions (Flask A)and anaerobic conditions (Flask B).Select the correct statements.(Select all that apply)

A)Flask A will grow faster
B)Flask B will have a higher pH
C)Flask A will produce more ATP
D)Flask B will have a higher biomass
E)None is a correct statement

Question 55

Which of these methods will NOT ensure sterility?

A)Use of UV irradiation
B)ultrafiltration
C)Pasteurization
D)autoclaving
E)Use of gamma irradiation

Question 56

Many pharmaceutical products are heat sensitive so they are sterilized:

A)by ultraviolet radiation.
B)by ionizing radiation.
C)with ozone gas.
D)with chlorine gas.
E)by freezing.

Question 57

An instrument designed to use moist heat for sterilization is the:

A)Spectrophotometer
B)Electric oven
C)Autoclave
D)Hemocytomer
E)Ultrafiltration device

Question 58

You grow E.coli for twelve hours in two identical glucose-containing flasks under aerobic conditions (Flask A)and anaerobic conditions (Flask B).Select the correct statements.(Select all that apply)

A)Flask A will grow faster
B)Flask B will have a higher pH
C)Flask A will produce more ATP
D)Flask B will have a higher biomass
E)None is a correct statement

Question 59

You grow Micrococcus luteus,an obligate aerobe for twelve hours in two identical glucose-containing flasks under aerobic conditions (Flask A)and anaerobic conditions (Flask B).Select the correct statements.(Select all that apply)

A)Flask A will grow faster
B)Flask B will have a higher pH
C)Flask A will produce more ATP
D)Flask B will have a higher biomass
E)None is a correct statement

Question 60

Vibrio natriegens has a growth rate of:

A)6 generations per hour
B)10 minutes
C)20 minutes
D)3 generations per hour
E)0)3 generations per hour

Question 61

You are using triple sugar iron agar to differentiate intestinal bacteria.You believe you have isolated Pseudomonas.What appearance would you see in the culture tube?

A)Red slant,red butt
B)Yellow slant,red butt
C)Red slant,yellow butt
D)Yellow slant,yellow butt
E)Red slant,yellow butt with black H₂S production

Question 62

Triple sugar iron agar results allow the conclusion(s): (Select all that apply)

A)Pseudomonas does not ferment lactose
B)Proteus does not ferment glucose
C)Shigella does not ferment glucose
D)E)coli does not ferment lactose
E)Salmonella does produce H₂S

Question 63

The bile salts in MacConkey agar,which inhibits the growth of many bacteria,make this media differential in nature.

Question 64

Nucleic acids strongly absorb _____________ radiation of 260 nm.

Question 65

You are using triple sugar iron agar to differentiate intestinal bacteria.You believe you have isolated Salmonella.What appearance would you see in the culture tube?

A)Red slant,red butt
B)Yellow slant,red butt
C)Red slant,yellow butt
D)Yellow slant,yellow butt
E)Red slant,yellow butt with black H₂S production

Question 66

A device used for the continuous culturing of bacteria is called a _________.

Question 67

The use of a good antiseptic,such as Betadine,results in sterilization.

Question 68

Generation time is the average time it takes an actively growing cell in a population to divide.

Question 69

The selection of Neisseria,a fastidious (slow-growing)microbe relies heavily on
Selection by: (Select all that apply)

A)Antibiotic resistance of competitor fungi
B)Antibiotic sensitivity of competitor bacteria
C)Antibiotic sensitivity of Neisseria
D)Antibiotic resistance of Neisseria
E)None is a correct choice

Question 70

You are using triple sugar iron agar to differentiate intestinal bacteria.You believe you have isolated Shigella.What appearance would you see in the culture tube?

A)Red slant,red butt
B)Yellow slant,red butt
C)Red slant,yellow butt
D)Yellow slant,yellow butt
E)Red slant,yellow butt with black H₂S production

Question 71

In the environment,one microorganism often provides a nutrient for another microbe that is unable to synthesize the nutrient by itself.What is this type of environment called? (Select all that apply)

A)auxotrophy
B)prototrophy
C)consortium
D)biofilm
E)eutrophy

Question 72

Triple sugar iron agar results allow the conclusion(s): (Select all that apply)

A)Pseudomonas does not ferment glucose
B)Proteus does ferment lactose
C)Shigella does not ferment lactose
D)E)coli does ferment glucose
E)Salmonella does not produce H₂S