Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

SAC Microbiology > Lecture 6 > Flashcards

Lecture 6 Flashcards

You may prefer our related Brainscape-certified flashcards:
Biology 101 flashcards
1
Q

What class of microbe grows best between the temperatures of 50 and 80°C?

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

A

Thermophile

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is a chemically defined medium?

A) a medium with poorly defined ingredients
B) a medium containing components that allow for the growth of fastidious organisms
C) a medium designed to favor the growth of one organism over another
D) a medium in which all chemical components are clearly defined and added in precise amounts

A

D) a medium in which all chemical components are clearly defined and added in precise amounts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

A ____ medium is one in which all chemical components are defined and added in precise amounts.

A

synthetic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Which of the following is happening during the exponential phase of bacterial growth?

A) A key nutrient has run out, resulting in equal cell growth rate and death rate.
B) Cells are synthesizing components needed to initiate rapid growth.
C) Cells are growing and dividing at the maximum rate possible.
D) Cells are dying at an exponential rate.

A

C) Cells are growing and dividing at the maximum rate possible.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

During the ____ phase, cells are growing at their maximum rate as determined by the species and the type of media in which they are growing.

A

expontential

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Which of the following statements is true regarding biofilm development?

A) Biofilms pose no threat to humans.
B) Biofilms are known to increase the sensitivity of mircroorganisms to antibiotics.
C) Quorum sensing does not require a concentration of a signaling molecule before the initiation of gene expression changes.
D) After quorum sensing, cells begin to produce exopolysaccharide.

A

D) After quorum sensing, cells begin to produce exopolysaccharide.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Once the production of quorum-sensing molecules reaches a high enough concentration, the cells in a biofilm begin to produce ?

A

exopolysaccharide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Which of the following techniques for measuring bacterial growth is considered an indirect count?

A) Fluorescence Activated Cell Sorter (FACS)
B) Viable plate count
C) Microscopic count using a hemocytometer
D) Optical Density

A

Optical Density

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Which phase of bacterial growth represents what is occurring when a pathogenic organism is initially inoculated into a susceptible host?

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

A

B) lag phase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

The ____ phase occurs when an organism is inoculated into a new environment and must synthesize the necessary cell components to survive in that environment, much like a pathogenic organism freshly inoculated into a susceptible host.

A

Lag

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is happening at stage II of sporulation?

A) A septum forms, separating the forespore from the mother cell
B) The mother cell engulfs the forespore
C) The chromosome of the mother cell disintegrates
D) The forespore develops a cortex layer of peptidoglycan

A

A) A septum forms, separating the forespore from the mother cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is phototrophy?

A) Energy extracted from oxidation of organic compounds
B) Energy extracted from inorganic chemicals
C) Energy extracted from chemical reactions triggered by absorption of light
D) Energy extracted from oxidation-reduction reactions

A

C) Energy extracted from chemical reactions triggered by absorption of light

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Which of the following is false about counting viable cells?

A) CFU (colony forming units) are counted instead of individual cells
B) Only 30-300 CFU’s are statistically valid
C) Colonies on the plate represent a fraction of live cells in the original sample
D) You determine the number of live cells in a broth culture

A

D) You determine the number of live cells in a broth culture

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Bacteria grown in a closed system demonstrates four distinct growth phases. Which phase is characterize by the death rate being equal to the reproduction rate?

A) Lag phase
B) Stationary phase
C) Death phase
D) Log phase

A

B) Stationary phase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

A student completes a streak plate correctly except that the loop is not heated and cooled after each pass. What is the most likely outcome of this streak plate?

A) No bacterial growth would be visible on the plate.
B) More individual colonies would be visible in the first section streaked.
C) Individual colonies would not be visible on the plate.
D) More individual colonies would be visible in the second section of the plate.

A

C) Individual colonies would not be visible on the plate.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Bacteria enter a cut on a person’s hand. The infection will take some time to become noticeable because the bacteria are in which phase?

A) Log phase
B) Stationary phase
C) Lag phase
D) Death phase

A

C) Lag phase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How will the enzymes of thermophilic bacteria fare at human body temperature (37ºC)?

A) The enzymes will function more slowly than usual.
B) The enzymes will function more quickly than usual.
C) The enzymes will denature.
D) The enzymes will function as usual.

A

A) The enzymes will function more slowly than usual.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Which type of microorganism cannot survive in the presence of oxygen?

A) Obligate anaerobes
B) Barophiles
C) Obligate aerobes
D) Microaerophiles

A

A) Obligate anaerobes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Which of the following statements about biofilms is false?

A) Biofilms can form on rocks.
B) Biofilms cause dental plaque.
C) Biofilms are very sensitive to antibiotics.
D) Biofilms on medical implants can cause infections.

A

C) Biofilms are very sensitive to antibiotics.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Which of the following is most useful when trying to obtain a pure culture?

A) liquid medium
B) rich medium
C) complex medium
D) solid medium

A

D) solid medium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Which of the following techniques for measuring bacterial growth is not useful for differentiating between living and dead cells?

A) viable plate count
B) direct count under a microscope
C) fluorescence microscopy
D) FACS

A

B) direct count under a microscope

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Which of the following is a potential problem with the viable-plate-count method of measuring bacterial growth?

A) It is very rarely used and thus the results are not well accepted in the scientific community.
B) It underestimates the number of living cells in a culture.
C) It requires use of expensive fluorescent dyes.
D) It cannot distinguish between living and dead cells.

A

B) It underestimates the number of living cells in a culture.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Which phase of bacterial growth represents what is occurring when a pathogenic organism is initially inoculated into a susceptible host?

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

A

A) lag phase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Which of the following organisms cannot be grown in an airtight jar containing palladium pellets?

A) facultative anaerobe
B) aerotolerant anaerobe
C) strict aerobe
D) strict anaerobe

A

C) strict aerobe

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Which of the following temperature classifications contains organisms not capable of causing disease in humans?

A) facultative anaerobe
B) strict aerobe
C) strict anaerobe
D) All temperature classifications contain some organisms capable of causing disease.

A

D) All temperature classifications contain some organisms capable of causing disease.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What characteristic of biofilms can make treatment of infections they cause difficult?

A) death of cells in the interior of the biofilm
B) production of antibiotic resistance mechanisms by the organisms in the biofilm
C) organisms that cause infections are not known to form biofilms.
D) dispersion of cells in the biofilm

A

B) production of antibiotic resistance mechanisms by the organisms in the biofilm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

A Biofilm is a mass of bacteria constructed of a ____ species or ____ collaborating species.

A

Single; multiple

28
Q

Biofilms do what to infections?

A

Exacerbate infections

29
Q

Biofilms are found on multiple types of ?

A

Surfaces

30
Q

T/F

Biofilms can be organic or inorganic.

A

True

31
Q

What contains only chemically known components?

A

Chemically defined media

32
Q

What favors the growth of some microorganisms while inhibiting others?

A

Selective media

33
Q

What helps distinguish bacteria by the color of the colonies or the change in the medium?

A

Differential media

34
Q

What is NOT a characteristic of fermentation?

A

contains an electron transport chain

35
Q

What media is most useful when trying to obtain a pure culture?

A

solid media

36
Q

T/F

Quorum sensing always occurs between members of the same species.

A

false

37
Q

an organism that grows equally well with or w/o oxygen

A

Aerotolerant anaerobes

38
Q

an organism that can grow without oxygen, but grows best with it

A

Facultative anaerobe

39
Q

an organism that requires a low level of oxygen (less than atmospheric normal)

A

Microearophile

40
Q

an organism that requires oxygen to survive

A

Obligate aerobe

41
Q

an organism that requires an oxygen-free environment

A

Obligate anaerobe

42
Q

Bacteria most commonly reproduce using which of the following methods?

A

binary fission

43
Q

a culture medium consisting of agar, peptone, and beef heart is a ?

A

complex medium

44
Q

T/F

an isolated colony on a streak plate contains millions (or even billions) of identical cells all rising from one initial cell

A

True

45
Q

a sample of milk is tested for its bacterial content in a plate count assay. A one milliliter sample of the milk is diluted in a 1:10 dilution series. One milliliter of the third dilution tube is plated in a pour plate. After incubation, the plate has 54 colonies, indicating that the original milk sample contained:

a. 540,000 cells per milliliter
b. 540 cells per milliliter
c. 5,400 cells per milliliter
d. 54 cells per milliliter
e. 54,000 cells per milliliter

A

54,000 cells per milliliter

46
Q

Which of the following is an advantage of the standard plate count?

a. determines the number of viable cells
b. provides immediate results
c. can be used to count heat-sensitive bacteria
d. can be performed on very dilute samples, such as lake water
e. can readily count cells that form aggregates

A

a. determines the number of viable cells

47
Q

Which of the following is an advantage of the direct microscopic count?

a. can readily count organisms that are motile
b. requires no incubation time
c. sample volume is unknown
d. requires a large number of cells
e. can easily distinguish live from dead cells

A

b. requires no incubation time

48
Q

which of the following is the best definition of generation time?

a. the time needed for nuclear division
b. the duration of log phase
c. the minimum rate of doubling
d. the length of time needed for a cell to divide
e. the length of time needed for lag phase

A

d. the length of time needed for a cell to divide

49
Q

Which of the following is NOT a direct method to measure microbial growth?

a. standard plate count
b. filtration on a support membrane followed by incubation on medium
c. metabolic activity
d. direct microscopic count
e. most probable number (MPN)

A

c. metabolic activity

50
Q

an experiment began with 4 cells in log phase and ended with 128 cells. How many generations did the cells go through?

a. 5
b. 4
c. 32
d. 64
e. 6

A

a. 5

51
Q

three cells with generation times of 60 minutes are inoculated into a culture medium. Assuming no lag phase takes place, how many cells are there after 5 hours?

a. 15
b. 96
c. 180
d. 900
e. 32

A

b. 96

52
Q

which of the following methods used to count microbes is correctly identified as direct or indirect?

a. turbidity–direct method
b. plate count–indirect measurement
c. filtration–direct method
d. dry weight–direct measurement

A

c. filtration–direct method

53
Q

the ____ method is used to indirectly measure microbial growth of filamentous bacteria and molds.

a. turbidity measurement
b. metabolic activity
c. spread plate
d. dry weight
e. pour plate

A

d. dry weight

54
Q

The pour plate and spread plate methods are used to plate ?

A

serial dilutions

55
Q

Cells in biofilms coordinate their activity by communicating through ?

A

quorum sensing

56
Q

____ require high salt concentration in

the medium.

A

Halophiles

57
Q

Which of the following methods would be used to
measure the concentration of bacterial
contamination in processed peanut butter?

A. turbidity measurement
B. total plate count
C. dry weight measurement
D. direct counting of bacteria on a calibrated
slide under the microscope
A

B. total plate count

58
Q

In which phase would you expect to observe the most endospores in a Bacillus cell culture?

A. death phase
B. lag phase
C. log phase
D. log, lag, and death phases would all have roughly the same number of endospores.

A

A. death phase

59
Q

During which phase would penicillin, an
antibiotic that inhibits cell-wall synthesis, be most effective?

A. death phase
B. lag phase
C. log phase
D. stationary phase

A

C. log phase

60
Q

Which of the following is the best definition of generation time in a bacterium?

A. the length of time it takes to reach the log phase
B. the length of time it takes for a population of cells to double
C. the time it takes to reach stationary phase
D. the length of time of the exponential phase

A

B. the length of time it takes for a population of cells to double

61
Q

If a culture starts with 50 cells, how many cells will be present after five generations with no cell death?

A. 200
B. 400
C. 1600
D. 3200

A

C. 1600

62
Q

Quorum sensing is used by bacterial cells to determine which of the following?

A. the size of the population
B. the availability of nutrients
C. the speed of water flow
D. the density of the population

A

D. the density of the population

63
Q

Pseudomonas aeruginosa is a common
pathogen that infects the airways of patients with cystic fibrosis. It does not grow in the absence of oxygen. The bacterium is probably which of the following?

A. an aerotolerant anaerobe
B. an obligate aerobe
C. an obligate anaerobe
D. a facultative anaerobe

A

B. an obligate aerobe

64
Q

Streptococcus mutans is a major cause of
cavities. It resides in the gum pockets, does not
have catalase activity, and can be grown outside
of an anaerobic chamber. The bacterium is
probably which of the following?

A. a facultative anaerobe
B. an obligate aerobe
C. an obligate anaerobe
D. an aerotolerant anaerobe

A

D. an aerotolerant anaerobe

65
Q

A soup container was forgotten in the
refrigerator and shows contamination. The contaminants are probably which of the following?

A. thermophiles
B. acidophiles
C. mesophiles
D. psychrotrophs

A

D. psychrotrophs

66
Q

Bacteria isolated from a hot tub at 39 °C are probably which of the following?

A. thermophiles
B. psychrotrophs
C. mesophiles
D. hyperthermophiles

A

C. mesophiles

67
Q

In which environment are you most likely to
encounter a hyperthermophile?

A. hot tub
B. warm ocean water in Florida
C. hydrothermal vent at the bottom of the
ocean
D. human body
A

C. hydrothermal vent at the bottom of the

ocean

SAC Microbiology (19 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions