Question 1

Generally the proteins of thermophiles

Accepted Answer

A)  resist denaturation. 
B)  react more efficiently with DNA. 
C)  are easily denatured. 
D)  have a particular amino acid sequence that restricts bond formation. 
E)  are easily denatured AND have a particular amino acid sequence that restricts bond formation. 
A)  resist denaturation. 
B)  react more efficiently with DNA. 
C)  are easily denatured. 
D)  have a particular amino acid sequence that restricts bond formation. 
E)  are easily denatured AND have a particular amino acid sequence that restricts bond formation.

Question 2

You are in charge of water quality for your city's water treatment plant. Of the methods at your disposal, which will be the most efficient and cheapest method of determining the number of viable bacteria in the water coming out of your plant?

Accepted Answer

A)  Direct counts using a microscope and a counting chamber. 
B)  Using a Coulter counter machine. 
C)  Performing serial dilutions of your samples and doing spread plate counts. 
D)  Using membrane filtration followed by placing the membrane in a growth medium for colony counts after incubation. 
E)  Biochemical analysis of secondary metabolites in the water that are given off by bacteria. 
A)  Direct counts using a microscope and a counting chamber. 
B)  Using a Coulter counter machine. 
C)  Performing serial dilutions of your samples and doing spread plate counts. 
D)  Using membrane filtration followed by placing the membrane in a growth medium for colony counts after incubation. 
E)  Biochemical analysis of secondary metabolites in the water that are given off by bacteria.

Question 3

A medium that inhibits the growth of organisms other than the one being sought is termed a(n)

Accepted Answer

A)  synthetic medium. 
B)  specific culture medium. 
C)  selective medium. 
D)  enrichment medium. 
A)  synthetic medium. 
B)  specific culture medium. 
C)  selective medium. 
D)  enrichment medium.

Question 4

You take absorbance readings on a spectrophotometer across a 6 hour culture of

Accepted Answer

A)  Clearly, something is 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)  When we establish a growth curve, we should actually plot the log of the number of viable cells vs. time. However, a spectrophotometer can only measure absorbance. Absorbance is NOT the same as the number of viable cells. Many of the cells in the tube are most likely dead, but the machine can't discriminate between a live cell and a dead one. This keeps the absorbance high even into the death phase. 
C)  It'll happen-E. coli just grow slowly. We haven't gotten to the end of the stationary phase yet. Be patient! 
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)  coli cells growing in tryptic soy broth (TS
B) . 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? 
A)  Clearly, something is 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)  When we establish a growth curve, we should actually plot the log of the number of viable cells vs. time. However, a spectrophotometer can only measure absorbance. Absorbance is NOT the same as the number of viable cells. Many of the cells in the tube are most likely dead, but the machine can't discriminate between a live cell and a dead one. This keeps the absorbance high even into the death phase. 
C)  It'll happen-E. coli just grow slowly. We haven't gotten to the end of the stationary phase yet. Be patient! 
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)  coli cells growing in tryptic soy broth (TS
B) . 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?

Question 5

MacConkey agar is

Accepted Answer

A)  a selective agar. 
B)  a differential agar. 
C)  a selective and differential agar. 
D)  used to distinguish between bacteria by the type of hemolysis observed. 
A)  a selective agar. 
B)  a differential agar. 
C)  a selective and differential agar. 
D)  used to distinguish between bacteria by the type of hemolysis observed.

Question 6

Freezing is an effective means of destroying bacteria.

Accepted Answer

A) True 
 B)False

Question 7

Organisms that are indifferent to the presence of oxygen and do not use it are

Accepted Answer

A)  aerotolerant anaerobes. 
B)  facultative anaerobes. 
C)  obligate aerobes. 
D)  microaerophiles. 
A)  aerotolerant anaerobes. 
B)  facultative anaerobes. 
C)  obligate aerobes. 
D)  microaerophiles.

Question 8

Bacteria may be stored

Accepted Answer

A)  on a slant in the refrigerator. 
B)  frozen in glycerol solution. 
C)  lyophilized. 
D)  in broth at 37°C. 
E)  on a slant in the refrigerator, frozen in glycerol solution AND lyophilized. 
A)  on a slant in the refrigerator. 
B)  frozen in glycerol solution. 
C)  lyophilized. 
D)  in broth at 37°C. 
E)  on a slant in the refrigerator, frozen in glycerol solution AND lyophilized.

Question 9

During which phase of the bacterial growth curve does a bacterial population become much more resistant to harmful conditions?

Accepted Answer

A)  lag phase 
B)  exponential phase 
C)  stationary phase 
D)  late log phase 
A)  lag phase 
B)  exponential phase 
C)  stationary phase 
D)  late log phase

Question 10

Trace elements

Accepted Answer

A)  include zinc, copper and manganese. 
B)  are required in large amounts. 
C)  may be needed for enzyme function. 
D)  are involved in maintaining pH in the cell. 
E)  include zinc, copper and manganese AND may be needed for enzyme function. 
A)  include zinc, copper and manganese. 
B)  are required in large amounts. 
C)  may be needed for enzyme function. 
D)  are involved in maintaining pH in the cell. 
E)  include zinc, copper and manganese AND may be needed for enzyme function.

Question 11

Peptone

Accepted Answer

A)  refers to a hydrolysate of carbohydrates used in growth media. 
B)  refers to a hydrolysate of proteins used in growth media. 
C)  consists of a water extract of beef. 
D)  consists of a mix of monosaccharides and oligosaccharides. 
E)  refers to a hydrolysate of proteins used in growth media AND consists of a water extract of beef. 
A)  refers to a hydrolysate of carbohydrates used in growth media. 
B)  refers to a hydrolysate of proteins used in growth media. 
C)  consists of a water extract of beef. 
D)  consists of a mix of monosaccharides and oligosaccharides. 
E)  refers to a hydrolysate of proteins used in growth media AND consists of a water extract of beef.

Question 12

During which phase of the bacterial growth curve does the total number of viable cells decline?

Accepted Answer

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

Question 13

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

Accepted Answer

A) True 
 B)False

Question 14

Mycobacterium leprae is typically found infecting the ears, toes and fingers of its host due to its

Accepted Answer

A)  requirement for well-oxygenated blood. 
B)  easy access to those parts. 
C)  need for cooler temperatures. 
D)  long incubation period. 
A)  requirement for well-oxygenated blood. 
B)  easy access to those parts. 
C)  need for cooler temperatures. 
D)  long incubation period.

Question 15

Agar replaced gelatin as the gelling (solidifying) agent for media because

Accepted Answer

A)  agar is much cheaper. 
B)  much fewer bacteria can break down agar than gelatin. 
C)  agar is solid at body temperature. 
D)  gelatin became unavailable during World War II. 
E)  much fewer bacteria can break down agar than gelatin AND agar is solid at body temperature. 
A)  agar is much cheaper. 
B)  much fewer bacteria can break down agar than gelatin. 
C)  agar is solid at body temperature. 
D)  gelatin became unavailable during World War II. 
E)  much fewer bacteria can break down agar than gelatin AND agar is solid at body temperature.

Question 16

In the growth curve of a bacteria population, the bacteria are rapidly increasing in number in the

Accepted Answer

A)  lag phase. 
B)  exponential (log) phase. 
C)  stationary phase. 
D)  decline phase. 
E)  boomer phase. 
A)  lag phase. 
B)  exponential (log) phase. 
C)  stationary phase. 
D)  decline phase. 
E)  boomer phase.

Question 17

A pure culture in exponential growth phase has a bacterial concentration of 6.4 x 108 cells/ml. If the bacterium has a generation time of 1 h, how long ago was the cell concentration 8.0 x 107 cells/ml?

Accepted Answer

A)  1 h 
B)  2 h 
C)  3 h 
D)  4 h 
A)  1 h 
B)  2 h 
C)  3 h 
D)  4 h

Question 18

The optimum pH for growth of most species of bacteria is

Accepted Answer

A)  pH 5. 
B)  pH 7. 
C)  pH 9. 
D)  pH 6. 
A)  pH 5. 
B)  pH 7. 
C)  pH 9. 
D)  pH 6.

Question 19

A microbe is discovered growing near a deep sea thermal vent. When researchers bring a sample up to the surface and try to grow it in a lab at room temperature in a normal incubator, they are unsuccessful. Why?

Accepted Answer

A)  The pressure isn't the same at sea-level as it is on the ocean floor. 
B)  Oxygen concentrations are very different between the two environments-it's possible the microbe is a strict anaerobe and is poisoned by the air (oxygen) in the lab. 
C)  Salt concentrations might be different in the media the researchers are attempting to use and the salt water the microbe is used to living in. This might be causing osmotic pressure differences that the microbe can't tolerate. 
D)  The temperature is probably very different-the bottom of the ocean would be very cold, while these researchers are trying to grow this microbe at room temperature. The enzymes in the cells are probably outside of their normal operating range at room temperature, and therefore nonfunctional. 
E)  All of the above. 
A)  The pressure isn't the same at sea-level as it is on the ocean floor. 
B)  Oxygen concentrations are very different between the two environments-it's possible the microbe is a strict anaerobe and is poisoned by the air (oxygen) in the lab. 
C)  Salt concentrations might be different in the media the researchers are attempting to use and the salt water the microbe is used to living in. This might be causing osmotic pressure differences that the microbe can't tolerate. 
D)  The temperature is probably very different-the bottom of the ocean would be very cold, while these researchers are trying to grow this microbe at room temperature. The enzymes in the cells are probably outside of their normal operating range at room temperature, and therefore nonfunctional. 
E)  All of the above.

Question 20

One would expect most strict anaerobic organisms to have superoxide dismutase.

Accepted Answer

A) True 
 B)False

Exam 4: Dynamics of Prokaryotic Growth

Generally the proteins of thermophiles

You are in charge of water quality for your city's water treatment plant. Of the methods at your disposal, which will be the most efficient and cheapest method of determining the number of viable bacteria in the water coming out of your plant?

A medium that inhibits the growth of organisms other than the one being sought is termed a(n)

You take absorbance readings on a spectrophotometer across a 6 hour culture of

MacConkey agar is

Freezing is an effective means of destroying bacteria.

Organisms that are indifferent to the presence of oxygen and do not use it are

Bacteria may be stored

During which phase of the bacterial growth curve does a bacterial population become much more resistant to harmful conditions?

Trace elements

Peptone

During which phase of the bacterial growth curve does the total number of viable cells decline?

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

Mycobacterium leprae is typically found infecting the ears, toes and fingers of its host due to its

Agar replaced gelatin as the gelling (solidifying) agent for media because

In the growth curve of a bacteria population, the bacteria are rapidly increasing in number in the

A pure culture in exponential growth phase has a bacterial concentration of 6.4 x 108 cells/ml. If the bacterium has a generation time of 1 h, how long ago was the cell concentration 8.0 x 107 cells/ml?

The optimum pH for growth of most species of bacteria is

A microbe is discovered growing near a deep sea thermal vent. When researchers bring a sample up to the surface and try to grow it in a lab at room temperature in a normal incubator, they are unsuccessful. Why?

One would expect most strict anaerobic organisms to have superoxide dismutase.

Humans and the Microbial World

The Molecules of Life

Microscopy and Cell Structure

Control of Microbial Growth

Metabolism: Fueling Cell Growth

The Blueprint of Life, From Dna to Protein

Bacterial Genetics

Biotechnology and Recombinant Dna

Identification and Classification of Prokaryotes

The Diversity of Prokaryotic Organisms

The Eukaryotic Members of the Microbial World

Viruses, Viroids and Prions

The Innate Immune Response

The Adaptive Immune Response

Host-Microbe Interactions

Immunologic Disorders

Applications of Immune Responses

Epidemiology

Antimicrobial Medications

Respiratory System Infections

Skin Infections

Wound Infections

Digestive System Infections

Genitourinary Infections

Nervous System Infections

Blood and Lymphatic Infections

Hiv Disease and Complications of Immunodeficiency

Microbial Ecology

Environmental Microbiology: Treatment of Water, Wastes, and Polluted Habitats

Food Microbiology

Filters

A pure culture in exponential growth phase has a bacterial concentration of 6.4 x 10⁸ cells/ml. If the bacterium has a generation time of 1 h, how long ago was the cell concentration 8.0 x 10⁷ cells/ml?