Question 1

Which of the following best describes a chemolithoautotroph?

Accepted Answer

An organism that uses inorganic compounds as its energy source and carbon dioxide as its carbon source

Question 2

A bacterium is found to grow optimally at 37°C, but can survive between 12°C and 45°C. To which temperature class does it most likely belong?

Accepted Answer

Mesophile

Question 3

Which of the following statements about the redox tower is correct?

Accepted Answer

The bigger the difference in redox potential between electron donor and acceptor, the more energy can be harvested as ATP.

Question 4

Which of the following is a correct equation for calculating bacterial generation time ($$g) if $$you know the initial number of cells ($$N_0$$), the final number of cells ($$N$$), and the time elapsed ($$t$$)?

Accepted Answer

$$g = \frac{t}{n}$$,\ where\ n = \frac{\log_{10} N - \log_{10} $$N_0$$}{0.301}$

Question 5

Which of the following best explains why Mycobacterium tuberculosis forms visible colonies on agar only after about 2 weeks?

Accepted Answer

It has a very slow doubling time, taking about 800 minutes to divide.

Question 6

Which of the following is NOT a macroelement required by most microorganisms?

Accepted Answer

Copper

Question 7

A bacterium that uses light as its energy source and organic compounds as its carbon source is classified as a:

Accepted Answer

Photoheterotroph

Question 8

During catabolism, which of the following is true regarding the fate of large polymeric molecules?

Accepted Answer

They are broken down into smaller molecules, which are then further degraded to release energy.

Question 9

Which of the following best describes the function of extracellular protease activity in bacteria?

Accepted Answer

It enables bacteria to break down proteins in the environment for nutrient acquisition.

Question 10

Which of the following is a correct statement about autotrophs?

Accepted Answer

They use carbon dioxide as their sole or principal carbon source.

Question 11

A culture of Clostridium perfringens is incubated at 43°C. If the initial cell number is $$1 	imes 10^3$ and the doubling time is 10 minutes, how many cells will there be after 1 hour, assuming exponential growth?

Accepted Answer

$$6.4 	imes 10^5$

Question 12

Which of the following best describes the relationship between temperature and microbial growth rate?

Accepted Answer

Growth rate displays a bell-shaped response to temperature, with an optimum closer to the minimum than the maximum.

Question 13

Which of the following is a trace element required by some enzymes for activity?

Accepted Answer

Copper

Question 14

Which of the following best describes the process of binary fission in bacteria?

Accepted Answer

It is characterized by the formation of a septum and division into two daughter cells.

Question 15

Which of the following is a correct description of a chemoorganoheterotroph?

Accepted Answer

Uses organic compounds as both energy and carbon source

Question 16

Which of the following is a likely consequence if a bacterium is grown at a temperature above its maximum cardinal temperature?

Accepted Answer

The bacterium will die or cease to grow due to denaturation of proteins.

Question 17

Which of the following best explains why oxygen concentration is a key factor influencing microbial growth?

Accepted Answer

Oxygen can be toxic to some microbes, while essential for others.

Question 18

Which of the following is a correct example of a photoautotroph?

Accepted Answer

Cyanobacteria

Question 19

Which of the following best describes the role of the proton motive force in microbial metabolism?

Accepted Answer

It is used to synthesize ATP from ADP and inorganic phosphate.

Question 20

A bacterium is able to oxidize H$$_2S $$for energy and uses CO$$_2 as $$its carbon source. Which metabolic classification does it belong to?

Accepted Answer

Chemolithoautotroph

Microbial Physiology, Nutrition, and Growth: Key Concepts and Mechanisms

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