Question 1

Which of the following best describes an obligate aerobe?

Accepted Answer

An organism that requires oxygen for growth and cannot survive without it.

Question 2

A culture of bacteria is grown in a medium and shows a rapid increase in cell number, followed by a plateau, and then a decline. Which phases of the bacterial growth curve are represented by these observations?

Accepted Answer

Log (exponential), stationary, and death phases.

Question 3

Which of the following equations correctly represents exponential (logarithmic) growth of bacteria?

Accepted Answer

$$N = N_0$ 	imes 2^n$$

Question 4

A microbiologist is culturing a bacterium that grows best at 37°C but can also grow at 25°C and 45°C. This organism is best classified as a:

Accepted Answer

Mesophile

Question 5

Which of the following best describes a chemoautotroph?

Accepted Answer

An organism that uses inorganic chemicals as an energy source and CO$$_2 as a $$carbon source.

Question 6

A bacterial culture is transferred to a new medium and shows no immediate increase in cell number. What is the most likely explanation for this observation?

Accepted Answer

The bacteria are in the lag phase, adapting to the new environment.

Question 7

Which of the following statements about fastidious organisms is correct?

Accepted Answer

They require specific and complex nutrients for growth.

Question 8

A patient presents with a wound infection caused by a bacterium that can only grow in the absence of oxygen. Which term best describes this organism?

Accepted Answer

Obligate anaerobe

Question 9

Which of the following best describes the process of catabolism?

Accepted Answer

The breakdown of complex molecules into simpler ones, releasing energy.

Question 10

A bacterium is isolated from a hot spring with a temperature of 80°C. Which term best describes this organism?

Accepted Answer

Hyperthermophile

Question 11

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

Accepted Answer

Uses light as an energy source and organic compounds as a carbon source.

Question 12

Which of the following best explains why cyanobacteria are important in the environment?

Accepted Answer

They are responsible for nitrogen fixation and oxygenic photosynthesis.

Question 13

A culture medium contains only glucose and ammonium salts as sources of carbon and nitrogen. Which type of organism would be able to grow in this medium?

Accepted Answer

Chemoorganotroph

Question 14

Which of the following is the correct sequence of phases in a typical bacterial growth curve?

Accepted Answer

Lag, log (exponential), stationary, death

Question 15

A microbiologist is studying a bacterium that can use either oxygen or nitrate as a terminal electron acceptor. Which term best describes this organism?

Accepted Answer

Facultative anaerobe

Question 16

Which of the following best describes the function of ATP in microbial metabolism?

Accepted Answer

It serves as the main energy currency, coupling catabolic and anabolic reactions.

Question 17

A bacterium is isolated from refrigerated food and grows optimally at 4°C. Which term best describes this organism?

Accepted Answer

Psychrophile

Question 18

Which of the following statements about metabolism is correct?

Accepted Answer

Metabolism includes both the synthesis and breakdown of molecules.

Question 19

A bacterial culture is in the stationary phase. Which of the following best explains what is happening in the culture?

Accepted Answer

The rate of cell division equals the rate of cell death.

Question 20

Which of the following best describes a thermophile?

Accepted Answer

An organism that grows best at high temperatures, typically between 45°C and 80°C.

Microbial Growth and Metabolism: Study Guide for Chapters 5 & 6

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