Question 1

Which process is primarily responsible for the increase in bacterial population size in a batch culture?

Accepted Answer

Binary fission

Question 2

During binary fission, which protein forms a ring at the site of division and is essential for septum formation?

Accepted Answer

FtsZ

Question 3

A cafeteria worker inoculates a quiche with 4 E. coli cells. By the time you purchase the quiche, there are 128 cells. How many generations did the cells go through? Use $$Nt = No 	imes 2^n.$$

Accepted Answer

7

Question 4

Which phase of the bacterial growth curve is characterized by a balance between cell division and cell death?

Accepted Answer

Stationary phase

Question 5

In a continuous culture system (chemostat), what remains constant?

Accepted Answer

Cell number

Question 6

Which environmental factor does NOT directly affect bacterial growth rate?

Accepted Answer

Light intensity

Question 7

Psychrophiles are adapted to survive at low temperatures. Which molecular adaptation is most characteristic of psychrophiles?

Accepted Answer

More unsaturated fatty acids in membranes

Question 8

Thermophiles have proteins with more interdomain bonds. What is the primary advantage of this adaptation?

Accepted Answer

Resistance to denaturation at high temperatures

Question 9

Which equation correctly calculates the number of generations ($$n) $$given initial ($$N_0) $$and final ($$N_t) $$cell numbers?

Accepted Answer

$$n = \frac{\log_{10} N_t - \log_{10} N_0$}{0.301}$$

Question 10

A culture is inoculated with $$5 	imes 10^6$ cells/mL and after 5 hours contains 5.4$$ 	imes $$10^9$$ cells/mL. What is the generation time ($$g) if$$ $$n = 10$$ generations occurred?

Accepted Answer

$$g = \frac{5}{10} = 0.5$$ hours

Question 11

Which type of bacteria would most likely be found in the hot springs of Yellowstone National Park?

Accepted Answer

Hyperthermophiles

Question 12

What is the primary mechanism by which bacteria minimize osmotic stress in hypertonic environments?

Accepted Answer

Synthesizing or importing compatible solutes

Question 13

Which enzyme is NOT involved in detoxifying reactive oxygen species in bacteria?

Accepted Answer

DNA polymerase

Question 14

Facultative anaerobes can survive in both the presence and absence of oxygen. Which metabolic pathway do they use when oxygen is available?

Accepted Answer

Oxidative phosphorylation

Question 15

Biofilms are resistant to antibiotics and environmental stresses. Which component of biofilms contributes most to this resistance?

Accepted Answer

Extracellular polymeric substance (EPS)

Question 16

Quorum sensing in bacteria is best described as:

Accepted Answer

A mechanism for bacteria to assess population density

Question 17

Which type of bacteria is most likely to cause food spoilage in refrigerated meat and dairy products?

Accepted Answer

Psychrotrophs

Question 18

Which equation describes the exponential growth of bacteria undergoing binary fission?

Accepted Answer

$$N_t = N_0$ 	imes 2^n$$

Question 19

Which environmental condition is most likely to favor the growth of acidophiles?

Accepted Answer

Volcanic soil

Microbial Growth: Mechanisms, Environmental Influences, and Laboratory Cultivation

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