Deck 5: Microbial Growth

Question 1

The cardinal temperatures are the

A) minimum temperatures.
B) maximum temperatures.
C) optimum temperatures.
D) minimum, optimum, and maximum temperatures taken together.

Answer 1

D

Question 2

Cell density in a chemostat is controlled by

A) the size of the initial inoculum.
B) the concentration of the limiting nutrient.
C) the dilution factor.
D) all of the above.

Answer 2

B

Question 3

Which environmental factor(s) influences microbial growth?

A) water availability
B) oxygen
C) pH
D) all of the above

Answer 3

D

Question 4

For most physiological experiments, it is desirable for cells to be in the

A) exponential phase.
B) lag phase.
C) stationary phase.
D) death phase.

Question 5

Cryptic growth occurs when

A) increases in cell population go unnoticed.
B) the exponential curve is marked by a very long generation time.
C) cells are increasing in size but not in number.
D) the number of cells being generated equals the number of cells dying.

Question 6

Which of the following forms of oxygen is/are generally toxic to living organisms?

A) hydroxyl radical
B) superoxide anion
C) hydrogen peroxide
D) all of the above

Question 7

Most organisms can tolerate a temperature range of about

A) 10°C.
B) 15- 20°C.
C) 50- 60°C.
D) 25- 40°C.

Question 8

When the population doubles during a constant time interval, the growth is said to be

A) cartesian.
B) exponential.
C) semilogarithmic.
D) linear.

Question 9

When water activity is low, an organism must

A) increase its internal solute concentration.
B) increase its external solute concentration.
C) decrease its external solute concentration.
D) decrease its internal solute concentration.

Question 10

In general, compared with most prokaryotic microorganisms, most eukaryotic microorganisms grow

A) faster.
B) slower.
C) at about the same rate.
D) at rates that are too variable to make an adequate comparison.

Question 11

Proteins involved in prokaryotic cell division are

A) divisomes.
B) MreB proteins.
C) Fts proteins.
D) none of these.

Question 12

The major shape- determining protein among prokaryotes is

A) MinE.
B) MreB.
C) ZipA.
D) FtsZ.

Question 13

In which type of culture(s) does one find a closed system?

A) chemostat cultures
B) batch culture
C) continuous culture
D) all of the above

Question 14

Superoxide dismutase and catalase work together to convert superoxide back to

A) oxygen.
B) ozone.
C) peroxide.
D) none of the above.

Question 15

The cytoplasmic membrane must be in a(n) state for proper functioning.

A) neutral
B) stable
C) elastic
D) semi- fluid

Question 16

Consider solution A (pH 6) and solution B (pH 9). Which of the following statements is CORRECT?

A) Solution A is 300 times more acidic than solution B.
B) Solution B is 1,000 times more alkaline (basic) than solution A.
C) Solution B is 3,000 times more alkaline (basic) than solution A.
D) Solution A is 3 times more acidic than solution B.

Question 17

Population growth is measured by

A) changes in the number of cells and in the cell mass.
B) changes in the number of cells.
C) changes in the cell mass.
D) changes in the amount of nutrient(s) in the culture medium.

Question 18

Superoxide dismutase is indispensable to

A) obligate anaerobes.
B) aerobes.
C) aerotolerant anaerobes.
D) all of the above.

Question 19

The process by which two cells arise from one is known as

A) meiosis.
B) conjugation.
C) mitosis.
D) binary fission.

Question 20

The ratio of the vapor pressure of the air in equilibrium with a substance to the vapor pressure of pure water is known as

A) positive water balance.
B) water activity.
C) vapor activity.
D) osmosis.

Question 21

Which of these statements is/are TRUE?

A) Nonphototrophic organisms are able to grow at higher temperatures than phototrophic organisms.
B) In general, prokaryotic organisms can grow at higher temperatures than eukaryotic organisms.
C) The most thermophilic prokaryotes are species of Archaea.
D) All of the above are true.

Question 22

The time interval required for the formation of two cells from one is called the

A) generation time.
B) growth rate.
C) growth time.
D) division rate.

Question 23

An organism capable of growth at full oxygen tensions of 21% is

A) anaerobic.
B) microaerophilic.
C) aerotolerant.
D) aerobic.

Question 24

The number of colonies obtained in a plate count does NOT depend on the

A) size of the colonies.
B) inoculum volume.
C) incubation time.
D) type of culture medium.

Question 25

Enzymes called create small openings in the prokaryotic cell wall that are formed at the FtsZ ring.

Question 26

Because two or more cells may clump together, instead of reporting "viable cell count" microbiologists often use the term .

Question 27

As a group, which organisms tend to be most acid- tolerant?

A) fungi
B) Bacteria
C) protists
D) Archaea

Question 28

What is the function of bactoprenol?

A) It supplies the energy necessary for transpeptidation to occur.
B) It triggers the recruitment of FtsZ and the initiation of the divisome.
C) It is a hydrophobic alcohol that transports peptidoglycan precursors across the cytoplasmic membrane.
D) It is responsible for forming the peptide cross- links between muramic acid residues in adjacent glycan chains.

Question 29

When counting colonies on an agar plate,

A) only viable colonies are counted.
B) it is assumed that each colony arose from only one cell.
C) the medium must be suitable for colonial growth.
D) All of the above apply.

Question 30

Serial dilutions are generally made

A) to reach a suitable dilution while minimizing error.
B) when the appropriate viable count is unknown.
C) based on powers of 10, although other serial dilution factors are possible.
D) All of the above apply.

Question 31

Organisms able to live in environments with high sugar concentrations are

A) halotolerant.
B) xerophiles.
C) osmophiles.
D) none of the above.

Question 32

Divisomes are responsible for

A) osmotolerant growth.
B) thermotolerant growth.
C) psychrotolerant growth.
D) none of these.

Question 33

A microbe growing in a refrigerator is likely a

A) hyperthermophile.
B) psychrophile.
C) mesophile.
D) thermophile.

Question 34

An agar plate for counting colonies and maximizing statistical validity should ideally contain

A) 20 to 200 colonies.
B) 30 to 300 colonies.
C) 10 to 1000 colonies.
D) 10 to 100 colonies.

Question 35

Under what conditions would a lag phase NOT occur?

A) when a stationary phase culture is transferred into fresh medium
B) when a culture is transferred from a rich medium to minimal medium
C) when an exponentially growing culture is transferred into fresh medium
D) when a culture subjected to UV light is transferred into fresh medium

Question 36

The time between inoculation and the beginning of growth is usually called the

A) lag phase.
B) dormant phase.
C) log phase.
D) death phase.

Question 37

The partition that is a result of the inward growth of the cytoplasmic membrane and cell wall from opposing directions is known as the

A) colony.
B) autolysin.
C) divisome.
D) septum.

Question 38

Growth is defined as an increase in

A) the number of colonies present in a culture.
B) the life span of individual cells.
C) the size of individual organisms.
D) the number of cells.

Question 39

Oxygen in its normal ground state is referred to as

A) singlet oxygen.
B) anhydrous oxygen.
C) doublet oxygen.
D) triplet oxygen.

Question 40

Formation of the divisome begins with the attachment of which protein in a ring around the center of the cell?

A) ZipA
B) MinE
C) MinC
D) FtsZ

Question 41

An organism that can grow at 0°C but whose optimum temperature is 20- 40°C is considered . These organisms are (more/less) widely distributed in nature than organisms that grow exclusively at cold temperatures.

Question 42

The optimal growth pH represents the pH of the intracellular environment.

Question 43

For most purposes, viable counting usually gives accurate information about the number of active cells present in a culture volume.

Question 44

With a few minor exceptions, the time required for a bacterial growth cycle is generally the same, regardless of the bacterial species.

Question 45

Many obligate anaerobes are killed by oxygen.

Question 46

The main reactions of cell synthesis are the polymerization reactions that make macromolecules from monomers.

Question 47

Taq polymerase was isolated from a thermophile and is used in the polymerase chain reaction (PCR) technique.

Question 48

An alkaliphile would likely be found in soda lakes and high carbonate soils.

Question 49

During stationary phase, many cellular functions continue, including and some
.

Question 50

An increase in microbial density is synonymous with growth.

Question 51

Turbidity measurements are rapid but are not particularly accurate.

Question 52

Substances added to a culture to keep the pH constant are known as _ .

Question 53

The rates of exponential growth (in the exponential phase) vary greatly.

Question 54

The process by which macromolecules are synthesized from monomers is called .

Question 55

FtsZ is related to , the important cell division protein in eukaryotes.

Question 56

Organisms with a specific requirement for salt are known as .

Question 57

is the term used to describe the maintaining of cultures in a constant environment. The system is then said to be in a(n) .

Question 58

Probably the most important environmental factor affecting microbial growth is _.

Question 59

Cold environments are usually sterile.

Question 60

The most common type of continuous culture device is called a(n) .

Question 61

Planktonic cells remain in suspension, while sessile cells adhere to a surface.

Question 62

Factors affecting an organism's minimal growth temperature are not entirely understood.

Question 63

Explain our present understanding of molecular adaptations to the cytoplasmic membrane that are present in thermophiles.

Question 64

A growth curve can typically be plotted by monitoring a microbial population in a batch culture.

Question 65

Organisms generally respond equally to a given environmental factor.

Question 66

One problem with batch cultures is the change in the chemical composition of the medium as growth progresses.

Question 67

Based on studies with obligate acidophiles, high concentrations of hydrogen ions are required for membrane stability.

Question 68

In a chemostat, growth rate and growth yield can be controlled independently.

Question 69

Direct microscope counting of cells is an easy and accurate method of computing the exact number of cells in a sample.

Question 70

In a chemostat, the doubling rate and population density can be controlled independently.

Question 71

Explain why clinical medicine has an interest in understanding bacterial cell division at the molecular level.

Question 72

The lag phase does NOT occur if all the cells in the culture are viable.

Question 73

In the stationary phase, there is no net increase or decrease in cell number.

Question 74

Organisms living in boiling springs must be rapid growers with fast doubling times.

Question 75

Some microbes can grow in boiling water.

Question 76

The optimum temperature is usually closer to the minimum temperature than the maximum temperature.

Question 77

Counting chambers are used for estimating the number of cells present in a liquid culture.

Question 78

Irreversible cell damage is more likely to occur at low rather than high temperatures.

Question 79

Knowledge of microbial growth patterns is useful in working with the control of microbial growth.

Question 80

The death phase applies to individual cells rather than populations.