Deck 7: Microbial Growth

Question 1

Which of the following can be used to isolate pure cultures of bacteria from mixtures?

A)spread plates
B)streak plates
C)pour plates
D)all of the choices

Answer 1

D

Question 2

Colonies grow most rapidly at the __________ where oxygen and nutrients are readily available; however,they grow less rapidly at the __________ where these materials have been depleted.

Answer 2

edge,center

Question 3

The size and shape of a colony is not useful for identification of a microorganism because most microorganisms produce colonies that are indistinguishable from one another.
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Answer 3

False

Question 4

Serial dilutions can be used to estimate the total number of bacterial cells in a solution,including living and dead cells.

Question 5

Mannitol salt agar (MSA)only allows the growth of halophiles (salt-loving microbes).Among the halophiles,mannitol fermenters release acid that turns the pH indicator yellow; mannitol nonfermenters leave the medium red.Onto MSA you inoculate a halophilic mannitol fermenter,a nonhalophilic mannitol fermenter,and a halophilic mannitol nonfermenter.Thus,the medium is acting as a __________ medium.

A)selective
B)differential
C)selective and differential
D)neither selective nor differential

Question 6

All fastidious microorganisms require which of the following for growth?

A)Oxygen.
B)Temperatures near normal for the human body.
C)Extra nutrients (such as whole blood).
D)Iron.

Question 7

Macroscopically visible growths or clusters of microorganisms on solid media are called __________.

Question 8

For surface cultivation of microorganisms,a sulfated polymer called agar can be extracted from __________ and added to liquid media in order to cause it to solidify.

A)bacteria
B)animal fat
C)algae
D)fungi

Question 9

Mannitol salt agar (MSA)only allows the growth of halophiles (salt-loving microbes).Among the halophiles,mannitol fermenters release acid that turns the pH indicator yellow; mannitol nonfermenters leave the medium red.Onto MSA you inoculate a halophilic mannitol nonfermenter and a nonhalophilic mannitol nonfermenter.Here the medium acts as a __________ medium.

A)selective
B)differential
C)selective and differential
D)enrichment

Question 10

Blood agar is both a differential and enriched medium.

Question 11

Growth media that will support the growth of many different types of microorganisms are called __________ __________ growth media,whereas those that are supplemented by blood or other rich nutrient sources in order to support the growth of fastidious organisms are called __________ media.

Question 12

Agar is an excellent solidifying agent for microbiological media because

A)it is not degraded by most microorganisms.
B)solid agar remains solid until the temperature is raised to 90 $\degree$ C,and liquid agar remains liquid if the temperature is lowered to 45 $\degree$ C.
C)it is not degraded by most microorganisms and solid agar remains solid until the temperature is raised to 90 $\degree$ C,and liquid agar remains liquid if the temperature is lowered to 45 $\degree$ C are correct.
D)agar provides an excellent source of nutrition for a variety of different microorganisms.

Question 13

Most bacterial and archaeal cells divide by

A)mitosis
B)meiosis
C)binary fission
D)all of these

Question 14

Media in which all components and their concentration are known are called __________ media.

A)transport
B)defined
C)selective
D)enrichment

Question 15

You would like to culture a bacterium that is growing in the lung of a human patient with pneumonia.Which media would be of most use in culturing this organism?

A)Transport media.
B)Mannitol salt agar.
C)MacConkey's agar.
D)Complex medium supplemented with whole blood.
E)None of the choices.

Question 16

A growth medium that favors the growth of some microorganisms but inhibits the growth of other microorganisms is a __________ medium.

A)selective
B)differential
C)selective and differential
D)neither selective nor differential

Question 17

A growth medium that distinguishes among different groups of bacteria on the basis of their biological characteristics is called a __________ medium.

A)selective
B)differential
C)enrichment
D)transport

Question 18

Media containing some ingredients of unknown chemical composition are called __________ media.

A)undefined
B)complex
C)defined
D)synthetic

Question 19

A given medium can be either selective or differential but not both.

Question 20

Mannitol salt agar (MSA)only allows the growth of halophiles (salt-loving microbes); nonhalophiles will not grow.Among the halophiles,mannitol fermenters will produce acid that turns the pH indicator yellow; mannitol nonfermenters leave the medium red.Onto MSA you inoculate a halophilic mannitol fermenter and a halophilic mannitol nonfermenter.In this case,the medium is acting as (a)__________ medium(s).

A)selective
B)differential
C)selective and differential
D)enrichment

Question 21

When a young,vigorously growing culture of bacteria is transferred to fresh medium of the same composition,the lag phase is usually short or absent.

Question 22

All bacterial and archaeal cells are diploid.

Question 23

Cells may enter stationary phase because of

A)the depletion of an essential nutrient.
B)a lack of available oxygen.
C)the accumulation of toxic waste products.
D)all of the choices
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Question 24

The actin-like protein that seems to be involved in determining cell shape is

A)MreB.
B)ActA.
C)SpnC.
D)FtsZ.

Question 25

A culture in a closed vessel to which no additional medium is added and from which no waste products are removed is called a __________ culture.

A)continuous
B)batch
C)fed-batch
D)semicontinuous
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Question 26

During the lag phase of microbial growth,the cells are metabolically inactive.

Question 27

The cell wall of bacteria constrains the ___________ _________ that results from the osmolarity of the cytoplasmic contents.

Question 28

Microorganisms are most nearly uniform in terms of chemical and physiological properties during __________ phase.

A)lag
B)exponential
C)stationary
D)decline
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Question 29

The __________ is a group of proteins needed for DNA synthesis that assembles at the origin of replication.

A)septum
B)replisome
C)prospore
D)none of these

Question 30

During cytokinesis,a critical step in septation is the assembly of the

A)replisome.
B)spindle body.
C)Z ring.
D)cytoskeletal spiral.

Question 31

Which of the following is the correct order for binary fission?

A)A septum forms at midcell,the cell elongates,replicates its chromosome,and separates the chromosome into the two parts of the cell.
B)The cell elongates,a septum forms at midcell,the cell replicates its chromosome,and separates the chromosome into the two parts of the cell.
C)The cell elongates,replicates its chromosome,and separates the chromosome into the two parts of the cell,and a septum forms at midcell.
D)None of these.
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Question 32

The site at which replication of DNA starts in bacterial cells is known as the __________ of ___________.

Question 33

The total number of viable microorganisms remains constant in stationary phase because

A)there is a balance between cell division and cell death.
B)there is a cessation of cell division even though the cells may remain metabolically active.
C)either there is a balance between cell division and cell death or there is a cessation of cell division even though the cells may remain metabolically active.
D)none of the choices
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Question 34

Given a log phase bacterial culture with 1 x 10⁶ cells per ml and a generation time of 30 minutes,how long does it take the culture to reach a density of 6.4 $\times$ 10⁷ cells per ml?

A)1 hour
B)2 hours
C)3 hours
D)4 hours

Question 35

Which of the following is a reason for the occurrence of a lag phase in a bacterial growth curve?

A)The cells may be old and depleted of ATP,essential cofactors,and ribosomes that must be synthesized before growth can begin.
B)The medium may be different from the previous growth medium so that the cells must synthesize new enzymes to use different nutrients.
C)The organisms may have been injured and require time to recover.
D)All of these are potential reasons.

Question 36

The limitation on microbial growth rate at high nutrient levels is

A)the rate of protein synthesis.
B)the rate of DNA replication.
C)the saturation of the transport proteins for nutrient uptake.
D)all of the choices.

Question 37

When a young,vigorously growing culture of bacteria is transferred to fresh medium of different composition,the lag phase is usually short or absent.

Question 38

The purpose of the penicillin binding proteins is to link phospholipids together in the cellular membrane.

Question 39

The length of the lag phase of growth can vary depending on

A)the condition of the microorganisms.
B)the nature of the growth medium.
C)the temperature.
D)all of the choices

Question 40

The process of forming a cross wall between two daughter cells is known as

A)replication
B)septation
C)sporulation
D)mitosis

Question 41

Growth is said to be __________ when all cellular components are synthesized at constant rates relative to one another.
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Question 42

Organisms that grow at 0 $\degree$ C and have a maximum growth temperature of 35 $\degree$ C are called

A)psychrotrophs.
B)psychrophiles.
C)frigiphiles.
D)mesophiles.

Question 43

Organisms that ignore oxygen and grow equally well in its presence or absence are called

A)facultative anaerobes.
B)microaerophiles.
C)aerotolerant.
D)anoxygenic.
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Question 44

Microbial __________ is an increase in cell constituents that may or may not be accompanied by an increase in cell number.
Learning Outcome: 07.01.01 Describe binary fission as observed in bacteria and archaea
Section: 07.01

Question 45

Organisms that grow well at 0 $\degree$ C and have optimum growth temperatures of 15 $\degree$ C or lower are called

A)psychrotrophs.
B)psychrophiles.
C)frigiphiles.
D)mesophiles.

Question 46

Which of the following is considered a cardinal growth temperature?

A)The minimum temperature.
B)The maximum temperature.
C)The optimum temperature.
D)All of these are considered cardinal growth temperatures.

Question 47

In a continuous culture system,the rate at which media is added and removed is called the __________ rate.

A)dilution
B)chemostatic
C)pass-through
D)flow-through
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Question 48

Which of these methods can be used to determine the number of viable microorganisms in a sample?

A)Light scattering in a spectrophotometer.
B)Measuring total cell mass.
C)Measuring colony forming units per ml.
D)Counting a known volume of cells in a hemocytometer.

Question 49

Organisms that do not require oxygen for growth but grow better in its presence are called

A)facultative anaerobes.
B)microaerophiles.
C)aerotolerant.
D)anoxygenic.

Question 50

A culture system with constant environmental conditions maintained through continual provision of nutrient and removal of wastes is called __________ culture system.

A)continuous
B)batch
C)fed-batch
D)semicontinuous
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Question 51

The __________ __________ is the length of time it takes for a population of microorganisms to double in number.

Question 52

At 4:00 p.m.a closed flask of sterile broth is inoculated with 10,000 cells.The lag phase lasts 1 hour.At 9:00 p.m.the culture enters stationary phase with a population of 65 million cells.At what time is the population half maximal?

A)6:30 p.m
B)7:20 p.m
C)8:20 p.m
D)8:40 p.m

Question 53

If all cell components are synthesized at constant rates relative to one another,the culture is said to be in __________ growth; however,if the rates of synthesis of some components change relative to the rates of synthesis of other components,the culture is said to be in __________ growth.

Question 54

Which of the following can be used to estimate the number of microorganisms in a culture?

A)Direct counts of microbial cells.
B)Counts of viable cells using colony growth procedures.
C)Measurements of microbial biomass.
D)All of the choices.

Question 55

One of the major advantages of a continuous culture system is that the cells can be maintained in the exponential growth phase for extended periods of time.

Question 56

An open system in which the growth rate is maintained by the removal and addition of media at such a rate as to maintain a constant cell density is called a

A)manostat.
B)chemostat.
C)turbidostat.
D)culturostat.

Question 57

At 4:00 p.m.a closed flask of sterile broth is inoculated with 10,000 cells.The lag phase lasts 1 hour.At 9:00 p.m.the log phase culture has population of 65 million cells.The approximate number of generations that has occurred is

A)5.
B)13.
C)21.
D)27.

Question 58

At 4:00 p.m.a closed flask of sterile broth is inoculated with 10,000 cells.The lag phase lasts 1 hour.At 9:00 p.m.the log phase culture has a population of 65 million cells.The mean generation time is approximately

A)10 minutes.
B)20 minutes.
C)30 minutes.
D)40 minutes.

Question 59

The growth rate of a given species of microorganism is dependent on the composition of the medium in which it is grown.

Question 60

An open system in which the growth rate is maintained by adding a nutrient (present in limiting quantities)at the same rate that medium containing microorganisms is removed is called

A)manostat.
B)chemostat.
C)turbidostat.
D)culturostat.
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Question 61

Organisms that have their optimum growth pH between 0.0 and 5.5 are called __________.

Question 62

Organisms that have their optimum growth pH between 5.5 and 8.0 are called __________.
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Question 63

Organisms that grow best at pH levels above 10 are called __________ __________.
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Question 64

Organisms that are damaged by the normal atmospheric levels of oxygen (20%)but require oxygen at levels of 2-10% for growth are called

A)facultative anaerobes.
B)microaerophiles.
C)aerotolerant.
D)anoxygenic.
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Question 65

Membranes of some thermophilic Archaea are stabilized by ether linked phospholipids.

Question 66

Membranes of thermophilic bacteria are stabilized by phospholipids with

A)fatty acids that tend to be more saturated.
B)fatty acids that have lower molecular weights.
C)fatty acids that have more double bonds.
D)all of the choices
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Question 67

When a microorganism is placed in a(n)__________ solution,water will enter into the cell and cause it to burst unless something is done to prevent this.

A)hypotonic
B)isotonic
C)hypertonic
D)osmotonic

Question 68

Organisms that require increased pressure for optimum growth are called

A)barotolerant.
B)osmotolerant.
C)barophilic.
D)osmophilic.

Question 69

Organisms that require high levels of sodium chloride in order to grow are called __________ organisms.

Question 70

Organisms that grow near deep-sea volcanic vents are likely to be

A)psychrophilic.
B)psychrotrophic.
C)mesophilic.
D)thermophilic.
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Question 71

Organisms that can grow in habitats with low water activity by maintaining a high internal salt concentration are called __________ organisms.

Question 72

Organisms that grow in the mud under relatively nonturbulent bodies of water are likely to be

A)obligate aerobes.
B)thermophilic.
C)barophilic.
D)anaerobes.
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Question 73

Many microbes that live in environments where there is high exposure to light use _______________ to provide protection from photoxidation by singlet oxygen.

Question 74

Organisms that are not drastically affected by increased pressure are called

A)barotolerant.
B)osmotolerant.
C)barophilic.
D)osmophilic.

Question 75

Obligate anaerobes are usually poisoned by molecular oxygen but may grow in aerobic habitats if associated with facultative anaerobes that use up all available oxygen.

Question 76

The membranes of psychrophilic bacteria have relatively high levels of __________ fatty acids,which allow them to remain semi-fluid at cold temperatures.

A)saturated
B)unsaturated
C)sterol
D)aromatic

Question 77

DNA of thermophiles is stabilized by binding of special nucleoid-associated proteins.

Question 78

Organisms that have their optimum growth pH between 8.5 and 11.5 are called __________.
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Question 79

Most microorganisms maintain their internal pH

A)near neutral (pH 7).
B)near their optimum growth pH.
C)slightly acidic (pH 4-6).
D)slightly alkaline (pH 8-10).

Question 80

Organisms that grow near deep-sea volcanic vents are likely to be

A)alkylophilic.
B)acidophilic.
C)barophilic or barotolerant.
D)picrophilic.
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