Question 1

Organisms may derive energy from

Accepted Answer

A)   sunlight AND temperature gradients.
B)   sunlight AND metabolizing chemical compounds.
C)   metabolizing chemical compounds AND temperature gradients.
D)   temperature gradients AND pH gradients.
E)   sunlight AND pH gradients.

Question 2

Medically important bacteria are often

Accepted Answer

A)   grown on agar containing blood AND grown at 4°C.
B)   grown at 37°C AND grown at a pH of 5.
C)   grown on agar containing blood AND grown at 37°C.
D)   grown on agar containing chocolate AND grown at 4°C.
E)   grown at a pH of 5 AND grown at 4°C.

Question 3

You take absorbance readings on a spectrophotometer across a 6-hour culture of E. coli cells growing in tryptic soy broth (TSB) . Your absorbance readings clearly indicate a lag phase, a log phase, and a stationary phase. You come back in and take readings at 8, 10, 12, 14, and 16 hours, but the absorbance number remains the same. Shouldn't it start coming down as the closed batch culture enters death phase? What's the most likely thing that is happening?

Accepted Answer

A)   Something is likely wrong with the spectrophotometer and it isn't measuring the correct values. Perhaps something is on the detector, making it register falsely high absorbance numbers.
B)   A spectrophotometer can measure absorbance as an indicator of cell number, but can't discriminate between a live cell and a dead one. The presence of dead cells keeps the absorbance high even into the death phase.
C)   E. coli just grows slowly, and has a long generation time. After 16 hours the cells are still in stationary phase, so the cell numbers are expectedly constant.
D)   Perhaps there's a big smudge of something on the tube that is blocking some of the light. This would lead to an elevated reading for every timepoint after the smudge was placed on the tube.
E)   There is no point in measuring the absorbance of the culture because the cells are bacterial. It would make more sense to measure would the transmission value.

Question 4

Differential media only allow certain bacteria to grow.

Accepted Answer

A) True 
 B)False

Question 5

Carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur may be considered

Accepted Answer

A)   minor elements.
B)   major elements.
C)   neutral elements.
D)   acidic elements.
E)   trace elements.

Question 6

There are five stages of growth in an open system of culture.

Accepted Answer

A) True 
 B)False

Question 7

Secondary metabolites may be antibiotics.

Accepted Answer

A) True 
 B)False

Question 8

You take a stool sample from Mrs. Thomas, and send it to the lab for analysis. You tell her that the technicians will do a variety of tests to confirm the identity of the organism causing her illness. The first thing that will be done is to inoculate some of her stool sample onto a medium called hektoen enteric (HE)  agar. On this medium, Shigella species produce blue-green colonies, while Salmonella produces blue-green colonies with a black center, and most Gram-positive bacteria do not grow at all. You explain to Mrs. Thomas that this type of medium is called a(n)  ________ medium.

Accepted Answer

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

Question 9

Shake tubes are used to determine the

Accepted Answer

A)   pH requirements for bacterial growth.
B)   temperature requirements for bacterial growth.
C)   oxygen requirements for bacterial growth.
D)   salt requirements for bacterial growth.
E)   nutrient requirements for bacterial growth.

Question 10

Organisms that require gaseous oxygen for metabolism are referred to as

Accepted Answer

A)   facultative aerobes.
B)   obligate aerobes.
C)   facultative anaerobes.
D)   microaerobes.
E)   obligate anaerobes.

Question 11

It is assumed that every colony observed on a streak plate arose from a single bacterium.

Accepted Answer

A) True 
 B)False

Question 12

The simplest technique for isolating bacteria in growth media is referred to as the

Accepted Answer

A)   streak-plate method.
B)   pour-plate method.
C)   serial dilution method.
D)   MPN method.
E)   bacterial growth method.

Question 13

Products that limit pH changes are often incorporated into media and are referred to as

Accepted Answer

A)   enzymes.
B)   buffers.
C)   bases.
D)   acids.
E)   neutrifiers.

Question 14

In addition to the few Shigella colonies that are noted, there are also abundant salmon pink colonies, around which the medium has turned yellow, losing its original blue color. You know that hektoen enteric agar must contain ________.

Accepted Answer

A)   lactose
B)   a pH indicator
C)   a weak acid
D)   malachite green
E)   penicillin

Question 15

The scientist that contributed most to the development of pure culture techniques was

Accepted Answer

A)   Alexander Fleming.
B)   Louis Pasteur.
C)   Edward Jenner.
D)   Robert Koch.
E)   Paul Ehrlich.

Question 16

MacConkey agar is

Accepted Answer

A)   a selective medium.
B)   a selective and differential medium.
C)   a differential medium.
D)   an enrichment medium.
E)   an anaerobic medium.

Question 17

The causative organism of gonorrhea is Neisseria gonorrhoeae, a fastidious, Gram-negative diplococcus. What does fastidious mean in this context?

Accepted Answer

A)   An organism with complex nutritional requirements.
B)   An organism that requires oxygen for growth.
C)   An organism that survives in the presence of specific antibiotics.
D)   An organism that only grows in pure culture.
E)   An organism that requires a living host.

Question 18

Generally the proteins of thermophiles

Accepted Answer

A)   resist denaturation.
B)   react more efficiently with DNA.
C)   are easily denatured.
D)   have very few amino acids.
E)   are larger than those of mesophiles.

Question 19

In microbiology, growth usually refers to an increase in size of the bacteria.

Accepted Answer

A) True 
 B)False

Question 20

All the bacterial cells that result from the replication of a single original bacterial organism are referred to as a

Accepted Answer

A)   mixed population.
B)   pure culture.
C)   lag culture.
D)   mutant culture.
E)   single culture.

Exam 4: Dynamics of Microbial Growth

Carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur may be considered

Correct Answer
verified

MacConkey agar is

Correct Answer
verified

Differential media only allow certain bacteria to grow.

Correct Answer
verified

Organisms that require gaseous oxygen for metabolism are referred to as

Correct Answer
verified

Organisms may derive energy from

Correct Answer
verified

In addition to the few Shigella colonies that are noted, there are also abundant salmon pink colonies, around which the medium has turned yellow, losing its original blue color. You know that hektoen enteric agar must contain ________.

Correct Answer
verified

The simplest technique for isolating bacteria in growth media is referred to as the

Correct Answer
verified

All the bacterial cells that result from the replication of a single original bacterial organism are referred to as a

Correct Answer
verified

It is assumed that every colony observed on a streak plate arose from a single bacterium.

Correct Answer
verified

The causative organism of gonorrhea is Neisseria gonorrhoeae, a fastidious, Gram-negative diplococcus. What does fastidious mean in this context?

Correct Answer
verified

Products that limit pH changes are often incorporated into media and are referred to as

Correct Answer
verified

Secondary metabolites may be antibiotics.

Correct Answer
verified

There are five stages of growth in an open system of culture.

Correct Answer
verified

In microbiology, growth usually refers to an increase in size of the bacteria.

Correct Answer
verified

Generally the proteins of thermophiles

Correct Answer
verified

The scientist that contributed most to the development of pure culture techniques was

Correct Answer
verified

Shake tubes are used to determine the

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Medically important bacteria are often

Correct Answer
verified

Exam 4: Dynamics of Microbial Growth

Carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur may be considered

Correct AnswerverifiedShow Answer

MacConkey agar is

Correct AnswerverifiedShow Answer

Differential media only allow certain bacteria to grow.

Correct AnswerverifiedShow Answer

Organisms that require gaseous oxygen for metabolism are referred to as

Correct AnswerverifiedShow Answer

Organisms may derive energy from

Correct AnswerverifiedShow Answer

In addition to the few Shigella colonies that are noted, there are also abundant salmon pink colonies, around which the medium has turned yellow, losing its original blue color. You know that hektoen enteric agar must contain ________.

Correct AnswerverifiedShow Answer

The simplest technique for isolating bacteria in growth media is referred to as the

Correct AnswerverifiedShow Answer

All the bacterial cells that result from the replication of a single original bacterial organism are referred to as a

Correct AnswerverifiedShow Answer

It is assumed that every colony observed on a streak plate arose from a single bacterium.

Correct AnswerverifiedShow Answer

The causative organism of gonorrhea is Neisseria gonorrhoeae, a fastidious, Gram-negative diplococcus. What does fastidious mean in this context?

Correct AnswerverifiedShow Answer

Products that limit pH changes are often incorporated into media and are referred to as

Correct AnswerverifiedShow Answer

Secondary metabolites may be antibiotics.

Correct AnswerverifiedShow Answer

There are five stages of growth in an open system of culture.

Correct AnswerverifiedShow Answer

In microbiology, growth usually refers to an increase in size of the bacteria.

Correct AnswerverifiedShow Answer

Generally the proteins of thermophiles

Correct AnswerverifiedShow Answer

The scientist that contributed most to the development of pure culture techniques was

Correct AnswerverifiedShow Answer

Shake tubes are used to determine the

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Medically important bacteria are often

Correct AnswerverifiedShow Answer

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