Question 1

Which of the following forms of oxygen is/are generally toxic to living organisms?

Accepted Answer

A) superoxide anion 
B) hydrogen peroxide 
C) hydroxyl radical 
D) superoxide,hydrogen peroxide,and hydroxyl radicals are all toxic 
A) superoxide anion 
B) hydrogen peroxide 
C) hydroxyl radical 
D) superoxide,hydrogen peroxide,and hydroxyl radicals are all toxic

Question 2

Justify why clinical medicine has an interest in understanding bacterial cell division at the molecular level.

Accepted Answer

Answers will vary,but one principle of t

Question 3

Cell density in a chemostat is controlled by

Accepted Answer

A) the concentration of the limiting nutrient. 
B) the dilution factor. 
C) the size of the initial inoculum. 
D) the concentration of the limiting nutrient,the dilution factor,and the size of the initial inoculum. 
A) the concentration of the limiting nutrient. 
B) the dilution factor. 
C) the size of the initial inoculum. 
D) the concentration of the limiting nutrient,the dilution factor,and the size of the initial inoculum.

Question 4

Would you expect a xerophilic organism to be halotolerant? Why or why not?

Accepted Answer

Yes,xerophiles are typically halotoleran

Question 5

Identifying bactoprenol inside the rare bacteria that lack peptidoglycan would be unexpected considering its role in membrane biosynthesis.

Accepted Answer

A) True 
 B)False

Question 6

By using a stain targeting living cells only,microscopy would be a better approach to enumerate the number of living cells in a soil sample compared to viability counts of serially diluted soil.

Accepted Answer

A) True 
 B)False

Question 7

One reason food is refrigerated to control microbial growth is because irreversible cell damage is more likely to occur at low rather than high temperatures.

Accepted Answer

A) True 
 B)False

Question 8

Many aromatic compounds used for growth substrates by bacteria are broken down during high heat autoclaving.Which is the BEST way to sterilize these aqueous solutions?

Accepted Answer

A) ethylene oxide gas treatment 
B) gamma irradiation 
C) 0)2 μm filter sterilization 
D) ultraviolet radiation 
A) ethylene oxide gas treatment 
B) gamma irradiation 
C) 0)2 μm filter sterilization 
D) ultraviolet radiation

Question 9

In a chemostat,growth rate and growth yield can be controlled independently.

Accepted Answer

A) True 
 B)False

Question 10

The number of colonies obtained in a plate count does NOT depend on the

Accepted Answer

A) inoculum volume. 
B) size of the colonies. 
C) type of culture medium. 
D) incubation time. 
A) inoculum volume. 
B) size of the colonies. 
C) type of culture medium. 
D) incubation time.

Question 11

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

Accepted Answer

Generation time (g)and division rate (v)

Question 12

Due to the relationship between the rate of enzyme catalysis and temperature,organisms living in boiling hot springs are also rapid growers with fast doubling times.

Accepted Answer

A) True 
 B)False

Question 13

The optimum temperature is usually closer to the minimum temperature than the maximum temperature.

Accepted Answer

A) True 
 B)False

Question 14

Sterility of a laminar flow hood is accomplished by filter-sterilized air passed through the hood quickly enough that non-sterile air does not flow into the work area.

Accepted Answer

A) True 
 B)False

Question 15

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 16

Direct microscope counting of stained cells is an accurate method for calculating the exact number of cells in a sample.

Accepted Answer

A) True 
 B)False

Question 17

When water activity is low,an organism must

Accepted Answer

A) increase its internal solute concentration. 
B) increase its external solute concentration. 
C) decrease its internal solute concentration. 
D) decrease its external solute concentration. 
A) increase its internal solute concentration. 
B) increase its external solute concentration. 
C) decrease its internal solute concentration. 
D) decrease its external solute concentration.

Question 18

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

Accepted Answer

Non-psychrophiles do not thrive in the c

Question 19

The rates of exponential growth (in the exponential phase)vary greatly according to the bacterial species as well as the bioavailable nutrients.

Accepted Answer

A) True 
 B)False

Question 20

What is the function of bactoprenol?

Accepted Answer

A) It is a hydrophobic alcohol that transports peptidoglycan precursors across the cytoplasmic membrane. 
B) It is responsible for forming the peptide cross-links between muramic acid residues in adjacent glycan chains. 
C) It triggers the recruitment of FtsZ and the initiation of the divisome. 
D) It supplies the energy necessary for transpeptidation to occur. 
A) It is a hydrophobic alcohol that transports peptidoglycan precursors across the cytoplasmic membrane. 
B) It is responsible for forming the peptide cross-links between muramic acid residues in adjacent glycan chains. 
C) It triggers the recruitment of FtsZ and the initiation of the divisome. 
D) It supplies the energy necessary for transpeptidation to occur.

Exam 5: Microbial Growth and Control

Which of the following forms of oxygen is/are generally toxic to living organisms?

Justify why clinical medicine has an interest in understanding bacterial cell division at the molecular level.

Cell density in a chemostat is controlled by

Would you expect a xerophilic organism to be halotolerant? Why or why not?

Identifying bactoprenol inside the rare bacteria that lack peptidoglycan would be unexpected considering its role in membrane biosynthesis.

By using a stain targeting living cells only,microscopy would be a better approach to enumerate the number of living cells in a soil sample compared to viability counts of serially diluted soil.

One reason food is refrigerated to control microbial growth is because irreversible cell damage is more likely to occur at low rather than high temperatures.

Many aromatic compounds used for growth substrates by bacteria are broken down during high heat autoclaving.Which is the BEST way to sterilize these aqueous solutions?

In a chemostat,growth rate and growth yield can be controlled independently.

The number of colonies obtained in a plate count does NOT depend on the

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

Due to the relationship between the rate of enzyme catalysis and temperature,organisms living in boiling hot springs are also rapid growers with fast doubling times.

The optimum temperature is usually closer to the minimum temperature than the maximum temperature.

Sterility of a laminar flow hood is accomplished by filter-sterilized air passed through the hood quickly enough that non-sterile air does not flow into the work area.

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.

Direct microscope counting of stained cells is an accurate method for calculating the exact number of cells in a sample.

When water activity is low,an organism must

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

The rates of exponential growth (in the exponential phase)vary greatly according to the bacterial species as well as the bioavailable nutrients.

What is the function of bactoprenol?

Microorganisms and Microbiology

Microbial Cell Structure and Function

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