Deck 6: Microbial Nutrition and Growth

Question 1

An aquatic microbe that can grow only near the surface of the water is probably which of the following?

A) a phototroph
B) a heterotroph
C) a chemotroph
D) a lithotroph
E) an anaerobe

Answer 1

A

Question 2

Nitrogen is a growth-limiting nutrient for many organisms because

A) it is necessary for the biosynthesis of amino acids.
B) it is required for synthesis of nucleotides.
C) it is required for lipid synthesis.
D) only a small number of bacteria are able to extract it from the atmosphere.
E) only a few microbes can extract it from the atmosphere, but all organisms require it for amino acid and nucleotide synthesis.

Answer 2

E

Question 3

A(n)________ organism require(s)oxygen for growth.

A) anaerobic
B) facultative anaerobic
C) aerotolerant
D) obligate aerobic
E) aerotolerant and an anaerobic

Answer 3

D

Question 4

All of the following are used to protect organisms from the toxic by-products of oxygen EXCEPT

A) carotenoids.
B) superoxide dismutase.
C) peroxidase.
D) protease.
E) catalase.

Question 5

A cell that uses an organic carbon source and obtains energy from light would be called a

A) photoheterotroph.
B) lithoautotroph.
C) photoautotroph.
D) chemoheterotroph.
E) chemoautotroph.

Question 6

An organism that produces catalase enzyme is protected from the harmful effects of

A) singlet oxygen (1O2).
B) hydroxyl radical (HO.).
C) peroxide anion (O22-).
D) superoxide radical (O2-).
E) molecular oxygen (O2).

Question 7

A microbe that grows only at the bottom of a tube of thioglycollate medium is probably a(n)

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

Question 8

An epidemiologist is investigating a new disease and observes what appear to be bacteria inside tissue cells in clinical samples from victims.The scientist wants to try to isolate the bacteria in the lab.What culture conditions are most likely to be successful?

A) culturing on blood agar plates
B) inoculation of EMB plates
C) incubation in an anaerobic culture system
D) inoculation of cell cultures
E) inoculation of a minimal medium broth

Question 9

Which of the following organisms would be most likely to contaminate a jar of pickles?

A) a neutrophile
B) a thermophile
C) an acidophile
D) an obligate anaerobe
E) a mesophile

Question 10

Human pathogens are classified as

A) thermoduric.
B) thermophiles.
C) mesophiles.
D) hyperthermophiles.
E) psychrophiles.

Question 11

Organisms that can grow with or without oxygen present are

A) obligate aerobes.
B) facultative anaerobes.
C) aerotolerant anaerobes.
D) obligate anaerobes.
E) either facultative anaerobes or aerotolerant anaerobes.

Question 12

Obligate anaerobes may be cultured in the laboratory

A) in a reducing medium.
B) in a standard incubator.
C) in standard Petri plates.
D) on blood agar plates.
E) in standard complex media.

Question 13

A microorganism grows in the lab on medium containing mineral salts but no organic compounds.The organism is likely to be a(n)

A) heterotroph.
B) autotroph.
C) chemotroph.
D) chemoheterotroph.
E) The answer cannot be determined from the information provided.

Question 14

Joan wants to discover a microbe capable of degrading an environmental contaminant.Which of the following culturing methods would be most effective for isolation of such an organism?

A) cell culture
B) chemostat
C) quorum sensing
D) enrichment culture
E) differential culture

Question 15

The events of binary fission are
I)the cell doubles in size
II)the DNA is replicated
III)the cell forms a septum
IV)the cell separates from its offspring
The correct order of these events is

A) I, III, II, IV.
B) II, III, I, IV.
C) IV, I, III, II.
D) II, I, III, IV.
E) I, II, IV, III.

Question 16

At temperatures higher than the maximum growth temperature for an organism,

A) proteins are permanently denatured.
B) membranes become too fluid for proper function.
C) hydrogen bonds within molecules are broken.
D) hydrogen bonds are broken and proteins are permanently denatured.
E) hydrogen bonds are broken, proteins are denatured, and membranes become too fluid.

Question 17

An organism that requires chemical nutrients which serve as final electron acceptors is a(n)

A) chemotroph.
B) phototroph.
C) lithotroph.
D) autotroph.
E) aerobe.

Question 18

In the process of ________,microbes detect the presence and density of other microbes and modify their metabolic activity in response.

A) quorum sensing
B) antagonism
C) mutualism
D) symbiosis
E) synergy

Question 19

A fastidious organism might be grown on which of the following types of media?

A) transport media
B) reducing media
C) enriched media
D) differential media
E) selective media

Question 20

A microbiologist inoculates a flask of broth with 1 ml of 100 bacterial cells/ml.The generation time of the species is 1 hour,and there is no lag phase.How long will it be before the culture contains more than 6,000 cells/ml?

A) 12 hours
B) 6 hours
C) 2 hours
D) 4 hours
E) 10 hours

Question 21

Which of the following statements is CORRECT regarding Figure 6.1?

A) Cells are actively growing only during the stage represented by B.
B) No cells are reproducing during the stage represented by D.
C) Cells are are most susceptible to antibiotics during the stage represented by A.
D) Cells are alive but not reproducing during the stage represented by A.
E) No new cells are being produced during the stage represented by C.

Question 22

The method of obtaining isolated cultures that utilizes surface area to physically dilute specimens is called

A) the pour-plate technique.
B) serial dilution.
C) the streak-plate technique.
D) transport media.
E) enrichment culturing.

Question 23

Which of the following is an indirect method for estimating the number of microbes in a sample?

A) viable plate counts
B) turbidity
C) Coulter counter
D) MPN
E) membrane filtration

Question 24

The Most Probable Number (MPN)method is used

A) to estimate numbers of cells in samples with a high density of bacterial cells.
B) when samples contain obligate anaerobes.
C) to estimate numbers of cells in samples with a low density of bacterial cells.
D) to isolate autotrophic bacteria.
E) to determine the generation time of bacterial isolates.

Question 25

Which of the following methods provides information about the number of living cells in a sample of bacterial culture?

A) serial dilution and viable plate count
B) membrane filtration
C) a Petroff-Hauser counting chamber
D) flow cytometry
E) a Coulter counter

Question 26

When cells are metabolically active but not dividing,they are in the ________ phase.

A) stationary
B) log
C) lag
D) death
E) exponential

Question 27

Blood agar plates are an example of ________ medium.

A) differential
B) selective
C) reducing
D) defined
E) transport

Question 28

The ________ method provides an estimate of the CFUs (colony-forming units)in a sample.

A) Coulter-counter
B) viable plate-count
C) streak-plate
D) turbidity
E) direct microscopic-count

Question 29

Creating conditions in the laboratory that promote the growth of some microbes while inhibiting the growth of others is called

A) complex culturing.
B) reducing conditions.
C) enrichment culturing.
D) transport conditions.
E) differential culturing.

Question 30

The generation time of bacterial cells is shortest during the ________ phase.

A) death
B) lag
C) log
D) stationary
E) longitudinal

Question 31

The ________ of a population is the time it takes for the cells to double in number.

A) binary fission
B) exponential growth
C) generation time
D) arithmetic growth
E) log phase

Question 32

During which growth phase are bacteria more susceptible to antimicrobial drugs?

A) lag phase
B) log phase
C) stationary phase
D) death phase
E) The susceptibility is the same for all phases.

Question 33

Rates of cell production and cell death are approximately equal during the ________ phase of growth.

A) lag
B) log
C) death
D) stationary
E) intermediate

Question 34

________ are complex communities of various types of microbes that adhere to surfaces.

A) Aggregates
B) Colonies
C) Isolates
D) Biofilms
E) Media

Question 35

MacConkey agar plates represent ________ medium.

A) a minimal
B) a selective
C) a differential
D) both a differential and a selective
E) both a minimal and a selective

Question 36

A clinical sample labeled as "sputum" was collected from

A) the skin.
B) the blood.
C) the central nervous system.
D) a piece of tissue.
E) the lungs.

Question 37

A ________ is used in industrial microbiology to produce microbial products that are only synthesized during log phase growth.

A) Coulter counter
B) broth culture
C) spectrophotometer
D) pour plate
E) chemostat

Question 38

What types of media are commonly used to isolate anaerobic microbes?

A) defined media
B) differential media
C) complex media
D) reducing media
E) selective media

Question 39

The growth of bacterial cultures is best described as

A) arithmetic growth.
B) lag growth.
C) logarithmic growth.
D) cell division.
E) replication.

Question 40

The use of salt and sugar in preserving various types of foods is an application of which of the following concepts?

A) nitrogen fixation
B) osmotic pressure
C) pH
D) hydrostatic pressure
E) quorum sensing

Question 41

Microaerophiles are microbes that grow best at low

A) carbon dioxide levels.
B) pH values.
C) hydrostatic pressure.
D) oxygen levels.
E) salt concentrations.

Question 42

A laboratory protocol lists the following ingredients: 1 g sucrose,16.4 g Na2HPO4,1.5 g (NH4)3PO4,0.02 g CaCO3,KNO3,water to 1 liter and autoclave.This recipe is for a ________ medium.

A) defined agar
B) defined broth
C) complex broth
D) reducing agar
E) complex enrichment broth

Question 43

Differential media are not useful for isolation of microbes.

Question 44

Agar is a useful compound in the microbiology lab because it is an excellent nutrient for bacteria.

Question 45

Nitrogen fixation results in the production of atmospheric nitrogen gas (N2).

Question 46

A 0.1 ml sample of a log phase culture contains 10,000 bacterial cells/ml.It is added to 9.9 ml of fresh culture medium broth.Assume a generation time of 30 minutes,and no limiting nutrients.How many bacteria will be present in the entire broth culture after five hours?

A) 3.2 × 104
B) 5.0 × 105
C) 1.02 × 106
D) 6.0 × 106
E) 2.56 × 107

Question 47

The (peroxide/superoxide/hydroxyl)radical is formed during the incomplete reduction of O2 during electron transport in aerobes.

Question 48

A microorganism found living under conditions of high ________ is a barophile.

A) pH values
B) oxygen concentrations
C) hydrostatic pressure
D) carbon dioxide levels
E) salt concentrations

Question 49

Quorum sensing is involved in the development and propagation of a biofilm.

Question 50

A(n)(autotroph/lithotroph/organotroph)uses inorganic molecules as electron donors.

Question 51

A capnophile is a microorganism that thrives in conditions of high

A) carbon dioxide levels.
B) hydrostatic pressure.
C) oxygen levels.
D) pH.
E) salt concentration.

Question 52

Enrichment culturing may require use of controlled environmental conditions.

Question 53

The preferred method for long term storage of bacteria is (freezing/refrigeration/lyophilization).

Question 54

Flow cytometry makes use of fluorescence to count microbes.

Question 55

The (maximum/optimum/selective)growth temperature is the temperature at which an organism exhibits the highest growth rate.

Question 56

Organisms that require organic sources of carbon and energy are called (chemoheterotrophs/chemoautotrophs/autotrophs).

Question 57

The only effective way to store bacterial cultures for short periods of time is to arrest their metabolism by freezing.

Question 58

Obligate anaerobes have enzymes such as superoxide dismutase to protect them from the damaging effects of oxygen.

Question 59

Serial dilution can be used in combination with pour plates as a method for isolating pure cultures.

Question 60

Thermoduric mesophiles are often responsible for spoilage of improperly canned foods.

Question 61

A growth curve plots the (concentration/number/percentage)of viable organisms in a growing population over time.

Question 62

A pure culture is composed of cells that arise from a single (cell/inoculum/sample).

Question 63

Explain the similarities and differences between direct and indirect methods of measuring microbial growth,and give examples of each.

Question 64

Explain how temperature and pH levels can influence microbial infections in the human body.

Question 65

A new prokaryote is recovered from a remote saline hot spring.Design a set of experiments to determine whether the organism is thermophilic or thermoduric,halophilic or halotolerant.

Question 66

Alkalinophiles can survive in water up to pH (11.5/10/7.0).

Question 67

Compare and contrast the streak-plate method of isolation with the pour-plate method of isolation.

Question 68

Genetic methods of detecting microorganisms reveal that the number of bacterial species in nature exceeds previous estimates by several orders of magnitude.In human mouths,for example,it is estimated that 500-700 microbial species are normally present.Explain why previous estimates were low.

Question 69

A (Coulter counter/cytometer/spectrophotometer)can measure changes in the turbidity of a bacterial culture.

Question 70

Some organisms use vitamins as (oxidizers/antioxidants/peroxidases)to be able to live as aerobes.

Question 71

Culturing of intracellular parasites generally requires (enrichment/cell culture/low oxygen)conditions.

Question 72

A(n)(culture/specimen/inoculum)is a sample of microorganisms introduced into a growth medium.

Question 73

A (Coulter/Petroff-Hauser chamber/spectrophotometer)counter is used to count cells on a light microscope.

Question 74

A clinical sample from a mucus membrane is usually collected as a (biopsy/needle/swab)specimen.

Question 75

A sample placed into fresh medium is initially in the (lag/log/stationary)phase of microbial growth in most instances.