Question 1

Selective medium differs from differential medium because

Accepted Answer

A)  selective medium permits growth of more organisms than differential medium. 
B)  selective medium permits growth of a particular microbial type while differential medium is used to distinguish between types of organisms. 
C)  differential medium differentiates pathogens from nonpathogens while selective medium grows only pathogens. 
D)  differential medium contains growth inhibitors while selective medium does not. 
A)  selective medium permits growth of more organisms than differential medium. 
B)  selective medium permits growth of a particular microbial type while differential medium is used to distinguish between types of organisms. 
C)  differential medium differentiates pathogens from nonpathogens while selective medium grows only pathogens. 
D)  differential medium contains growth inhibitors while selective medium does not.

Question 2

The ratio of the vapor pressure of the air in equilibrium with a substance to the vapor pressure of pure water is known as

Accepted Answer

A)  water activity. 
B)  vapor activity. 
C)  positive water balance. 
D)  osmosis. 
A)  water activity. 
B)  vapor activity. 
C)  positive water balance. 
D)  osmosis.

Question 3

Organisms living in boiling hot springs often grow rapidly and have short doubling times.

Accepted Answer

A) True 
 B)False

Question 4

The thermal death time is the time needed to kill all the bacteria in a particular culture at a certain temperature.

Accepted Answer

A) True 
 B)False

Question 5

The optimal pH for growth of an organism refers to its intracellular environment.

Accepted Answer

A) True 
 B)False

Question 6

Direct microscopic counting of cells is an accurate method for estimating the number of viable cells in a sample.

Accepted Answer

A) True 
 B)False

Question 7

The optimum growth temperature for an organism is typically closer to its minimum temperature rather than the maximum temperature.

Accepted Answer

A) True 
 B)False

Question 8

Most mesophilic organisms can grow in a temperature range of

Accepted Answer

A)  0-15°C. 
B)  10-20°C. 
C)  20-45°C. 
D)  50-65°C. 
A)  0-15°C. 
B)  10-20°C. 
C)  20-45°C. 
D)  50-65°C.

Question 9

Use the formulas N = N₀2ⁿ and g = t/n.
N = final cell number, N₀ = initial cell number,
n = number of generations, t = time, g = generation time.
Find the generation time if N = 2 × 10⁸, N₀ = 3 × 10⁶ and t = 3 hours.

Accepted Answer

The number of generations (n) must first

Question 10

When counting colonies on an agar plate

Accepted Answer

A)  it is assumed that each colony arose from division of one or a few cells. 
B)  only viable colonies are counted. 
C)  the medium must be suitable for colony growth. 
D)  All of these answer choices are true. 
A)  it is assumed that each colony arose from division of one or a few cells. 
B)  only viable colonies are counted. 
C)  the medium must be suitable for colony growth. 
D)  All of these answer choices are true.

Question 11

Explain the present understanding of molecular adaptations to the cytoplasmic membrane as found in psychrophiles.

Accepted Answer

Non-psychrophiles do not thrive in the c

Question 12

Mesophiles typically have longer fatty acid tails and more saturated carbon-carbon bonds in their cytoplasmic tails compared with thermophiles.

Accepted Answer

A) True 
 B)False

Question 13

Explain the difference between the division rate and the generation time.

Accepted Answer

Generation time (g) and division rate (v

Question 14

In both the lag and stationary phase, there is no net increase or decrease in viable cells.

Accepted Answer

A) True 
 B)False

Question 15

Autoclaving and pasteurization are two processes that are both very effective for sterilization.

Accepted Answer

A) True 
 B)False

Question 16

Explain the present understanding of molecular adaptations to the cytoplasmic membrane that are present in thermophiles.

Accepted Answer

In thermophiles and most hyperthermophil

Question 17

Which of the following is/are transferred to daughter cells during bacterial cell division?

Accepted Answer

A)  only genomic DNA, the blueprint for everything the cell needs 
B)  individual genes and enzymes to later be brought together to form the genome 
C)  only the chromosome and enzymes to immediately begin cellular metabolism 
D)  chromosome, proteins, and all other cellular constituents 
A)  only genomic DNA, the blueprint for everything the cell needs 
B)  individual genes and enzymes to later be brought together to form the genome 
C)  only the chromosome and enzymes to immediately begin cellular metabolism 
D)  chromosome, proteins, and all other cellular constituents

Question 18

The lag phase does NOT occur if an exponentially growing culture is transferred into a nutrient rich medium with the same components and growth conditions as the previous medium.

Accepted Answer

A) True 
 B)False

Question 19

A microbiology student in a research lab repeated an experiment described by others using the identical bacterial isolate, the same growth medium, and the same growth conditions. However, the student was unable to achieve the same O.D. at 600 nm. What is the LEAST likely cause for this discrepancy in measured turbidity?

Accepted Answer

A)  One experiment used 16 mm wide test tubes while the other used 18 mm wide test tubes. 
B)  One experiment subtracted the yellow color of the growth medium away from the final turbidity reported whereas the other used colorless water. 
C)  One experiment vigorously dispersed the bacterial pellicle with vortexing while the other did not. 
D)  The two experiments were carried out at vastly different elevations and did not consider the influence of pressure. 
A)  One experiment used 16 mm wide test tubes while the other used 18 mm wide test tubes. 
B)  One experiment subtracted the yellow color of the growth medium away from the final turbidity reported whereas the other used colorless water. 
C)  One experiment vigorously dispersed the bacterial pellicle with vortexing while the other did not. 
D)  The two experiments were carried out at vastly different elevations and did not consider the influence of pressure.

Question 20

A bacterium such as a snow alga that is able to grow in cold temperatures is called a psychrophile.

Accepted Answer

A) True 
 B)False

Exam 5: Microbial Growth and Its Control

Selective medium differs from differential medium because

The ratio of the vapor pressure of the air in equilibrium with a substance to the vapor pressure of pure water is known as

Organisms living in boiling hot springs often grow rapidly and have short doubling times.

The thermal death time is the time needed to kill all the bacteria in a particular culture at a certain temperature.

The optimal pH for growth of an organism refers to its intracellular environment.

Direct microscopic counting of cells is an accurate method for estimating the number of viable cells in a sample.

The optimum growth temperature for an organism is typically closer to its minimum temperature rather than the maximum temperature.

Most mesophilic organisms can grow in a temperature range of

Use the formulas N = N₀2ⁿ and g = t/n. N = final cell number, N₀ = initial cell number, n = number of generations, t = time, g = generation time. Find the generation time if N = 2 × 10⁸, N₀ = 3 × 10⁶ and t = 3 hours.

When counting colonies on an agar plate

Explain the present understanding of molecular adaptations to the cytoplasmic membrane as found in psychrophiles.

Mesophiles typically have longer fatty acid tails and more saturated carbon-carbon bonds in their cytoplasmic tails compared with thermophiles.

Explain the difference between the division rate and the generation time.

In both the lag and stationary phase, there is no net increase or decrease in viable cells.

Autoclaving and pasteurization are two processes that are both very effective for sterilization.

Explain the present understanding of molecular adaptations to the cytoplasmic membrane that are present in thermophiles.

Which of the following is/are transferred to daughter cells during bacterial cell division?

The lag phase does NOT occur if an exponentially growing culture is transferred into a nutrient rich medium with the same components and growth conditions as the previous medium.

A bacterium such as a snow alga that is able to grow in cold temperatures is called a psychrophile.

The Microbial World

Microbial Cell Structure and Function

Microbial Metabolism

Molecular Information Flow and Protein Processing

Microbial Regulatory Systems

Molecular Biology of Microbial Growth

Viruses and Their Replication

Microbial Systems Biology

Viral Genomics, Diversity, and Ecology

Genetics of Bacteria and Archaea

Biotechnology and Synthetic Biology

Microbial Evolution and Systematics

Metabolic Diversity of Microorganisms

Functional Diversity of Microorganisms

Diversity of Bacteria

Diversity of Archaea

Diversity of Microbial Eukarya

Taking the Measure of Microbial Systems

Microbial Ecosystems

Nutrient Cycles

Microbiology of the Built Environment

Microbial Symbioses

Microbial Symbioses with Humans

Microbial Infection and Pathogenesis

Innate Immunity: Broadly Specific Host Defenses

Adaptive Immunity: Highly Specific Host Defenses

Clinical Microbiology and Immunology

Epidemiology

Person-to-Person Bacterial and Viral Diseases

Vectorborne and Soilborne Bacterial and Viral Diseases

Waterborne and Foodborne Bacterial and Viral Diseases

Eukaryotic Pathogens: Fungi, Protozoans, and Helminths

Filters