Deck 6: Microbial Nutrition and Growth

Question 1

In microbiology, the term "growth" usually refers to which of the following?

A) an increase in the number of microbial cells
B) an increase in the amount of ATP produced
C) an increase in a microbe's size
D) Both A and B are correct.
E) A, B, and C are correct.

Answer 1

A

Question 2

Human pathogens are classified as

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

Answer 2

A

Question 3

Tap water is used sometimes to prepare growth media in the laboratory because

A) it helps regulate osmotic pressure.
B) it provides microbes with important growth factors.
C) it reacts with some of the toxic forms of oxygen.
D) it equalizes the hydrostatic pressure of the culture.
E) it provides microbes with the necessary trace elements.

Answer 3

E

Question 4

Which of the following measurement techniques would be useful to quantify a species of bacteria that is difficult to culture?

A) membrane filtration
B) microscopic counts
C) MPN
D) viable plate counts
E) metabolic activity

Question 5

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

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

Question 6

Why is oxygen a beneficial molecule for obligate aerobes but a deadly one for obligate anaerobes?

A) Obligate anaerobes use oxygen in a different way than aerobes.
B) Obligate aerobes are not exposed to the adverse effects of electron transport chains.
C) Obligate anaerobes usually lack protective enzymes such as catalase.
D) Obligate anaerobes cannot transport oxygen into the cell.
E) None of the above is correct.

Question 7

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

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

Question 8

Joan wants to discover a microbe capable of degrading an environmental contaminant. Which of the following refers to the process she should use?

A) quorum sensing
B) enrichment culture
C) nitrogen fixation
D) lyophilization
E) binary fission

Question 9

Nitrogen

A) is a growth- limiting nutrient for many organisms.
B) is used to build proteins and carbohydrates.
C) is extracted from the atmosphere by a few types of bacteria.
D) Both A and C are correct.
E) A, B, and C are correct.

Question 10

Nutritionally, you are classified as which of the following?

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

Question 11

Organisms that require certain levels of hydrostatic pressure for optimal growth are called

A) barophiles.
B) halophiles.
C) mesophiles.
D) psychrophiles.
E) alkalinophiles.

Question 12

All of the following would be expected to grow in a candle jar EXCEPT:

A) strict anaerobes.
B) facultative anaerobes.
C) microaerophiles.
D) aerotolerant anaerobes.
E) capnophiles.

Question 13

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

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

Question 14

A microbiologist inoculates a growth medium with 1,000 bacterial cells/ml. If the generation time of the species is 30 minutes, how long will it be before the culture contains more than 10,000 cells/ml?

A) 3 hours
B) 1 hour
C) 5 hours
D) 3.5 hours
E) 2 hours

Question 15

A microbe that grows only slightly below the surface of a tube of thioglycolate medium is probably a(n)

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

Question 16

At which of the following temperatures would a psychrophile grow best?

A) 20°C
B) 40°C
C) 30°C
D) 50°C
E) 10°C

Question 17

Which of the following is NOT a cellular mechanism designed to cope with toxic forms of oxygen?

A) hydroxyl radicals
B) superoxide dismutase
C) carotenoids
D) catalase
E) peroxidase

Question 18

Which of the following elements is never a limiting nutrient in cells?

A) oxygen
B) carbon
C) nitrogen
D) sulfur
E) hydrogen

Question 19

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

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

Question 20

All of the following are true statements concerning the generation time of bacterial cells EXCEPT:

A) Generation time is the number of cell divisions per unit time.
B) Some bacteria have a generation time of 20 minutes or less.
C) Generation time is the time required for a bacterial cell to grow and divide.
D) Generation time can be affected by changes in chemical or physical conditions.
E) Most bacteria have a generation time of three hours or less.

Question 21

All of the following are true statements concerning binary fission of microbial cells EXCEPT:

A) Cells can remain attached after division is complete.
B) The chromosome of the cell is replicated.
C) Daughter cells produced can be of different sizes.
D) Elongation of the cell occurs and the chromosomes are pushed apart.
E) A septum is formed across the midline of the cell.

Question 22

All of the following ingredients might be found in complex media EXCEPT:

A) soy extract.
B) blood.
C) hydrogen peroxide.
D) yeast extract.
E) milk proteins.

Question 23

Which of the following quantification techniques can distinguish between living and dead cells in a culture?

A) a Coulter counter
B) microscopic counts
C) dry weight
D) turbidity
E) metabolic activity

Question 24

Which of the following techniques involves the use of three sets of five culture tubes each to estimate the number of bacteria in a sample?

A) most probable number
B) Coulter counter
C) metabolic activity
D) microscopic counts
E) membrane filtration

Question 25

Thioglycolate medium can be used to determine the oxygen requirements of a microbe.

Question 26

A specimen of urine is determined to contain 30 bacterial cells per microliter. How many cells would be present in a milliliter?

A) 300
B) 3,000
C) 30 million
D) 3
E) 30,000

Question 27

All of the following are true statements concerning biofilms EXCEPT:

A) The metabolic characteristics are the same as if the microbe were alone.
B) They contain different species.
C) A large percentage of bacterial diseases are caused by biofilms.
D) It is an example of symbiosis.
E) They attach to a surface.

Question 28

A colony- forming unit is the number of cells

A) that are in exponential phase in a culture.
B) that can be placed on a Petri plate.
C) in a particular specimen.
D) that produces one colony.
E) in a colony.

Question 29

All of the following are associated with the isolation of pure cultures EXCEPT:

A) colony- forming units.
B) axenic cultures.
C) streak plates.
D) crenation.
E) agar.

Question 30

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

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

Question 31

A Petroff- Hauser counting chamber is

A) a glass slide containing an etched grid for counting microbes directly using a microscope.
B) a device used to count numbers of bacterial colonies on a Petri plate.
C) a device that counts cells as they interrupt an electrical current.
D) an apparatus that traps bacterial cells on a membrane filter where they can be counted.
E) a device that measures the amount of light that passes through a culture.

Question 32

Nitrogen fixation is a process that occurs in only a few types of bacteria.

Question 33

Sodium thioglycollate is associated with which of the following types of media?

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

Question 34

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

Question 35

Which of the following is NOT a direct method for measuring the number of microbes in a sample?

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

Question 36

An obligate halophile will burst if placed in freshwater.

Question 37

Foods such as sauerkraut and dill pickles inhibit bacterial contamination because of the effects of these foods'

A) nitrogen content.
B) pH.
C) oxygen content.
D) osmotic pressure.
E) temperature.

Question 38

A device that removes wastes and adds fresh medium to bacterial cultures in order to prolong the log phase of a culture is called a

A) cytometer.
B) spectrophotometer.
C) chemostat.
D) Coulter counter.
E) pellicle.

Question 39

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

Question 40

Another term for the logarithmic growth of bacterial cells is

A) binary fission.
B) arithmetic growth.
C) generation time.
D) absorbance.
E) exponential growth.

Question 41

Destruction of red blood cells that produces a greenish- brown discoloration in blood agar is known as
.

Question 42

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

Question 43

In the death phase of the microbial growth curve, all cells have died.

Question 44

A selective medium can be formulated either by including inhibitory chemical substances or by leaving out a single crucial nutrient.

Question 45

The growth temperature is the temperature at which an organism exhibits the highest growth rate.

Question 46

Microbes that grow best at a pH of 6.5 to 7.5 are called _ .

Question 47

In spectrophotometry, 40% light transmission is the same thing as 60% absorbance of light.

Question 48

The radical is formed during the incomplete reduction of O2 by electron transport in aerobes.

Question 49

A film of cells at the surface of a broth is called a(n) .

Question 50

Cells that are exposed to hypertonic environments will exhibit _ .

Question 51

The conversion of nitrogen gas to ammonia is called _.

Question 52

A(n) _ plots the number of organisms in a growing population over time.

Question 53

The term refers to the cloudiness of a broth culture as bacteria reproduce in it.

Question 54

A(n) _ is a sample of microorganisms introduced into a growth medium.

Question 55

microorganisms can survive for brief periods of time at high temperatures.

Question 56

Quorum sensing is a process by which bacteria respond to the density of other bacteria in their environment.

Question 57

A(n) is a single cell or a group of cells that gives rise to a pure culture.

Question 58

Immediately after inoculation, a bacterial culture enters the , where cells are adjusting to their new environment.

Question 59

is a gelling agent derived from algae that is useful for creating solid growth media.

Question 60

is a method of counting cells that have been stained or tagged with fluorescent dyes.

Question 61

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

Question 62

Explain how aerobic organisms tolerate the presence of oxygen in their metabolic pathways despite its toxic properties.

Question 63

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

Question 64

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

Question 65

What are fastidious microorganisms, and what kinds of issues must be considered when they are grown in the laboratory?