Question 1

Which of the following best describes a chemoautotroph?

Accepted Answer

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

Question 2

A bacterium that can grow in the presence or absence of oxygen, but grows better with oxygen, is classified as which of the following?

Accepted Answer

Facultative anaerobe

Question 3

Which of the following equations correctly represents the calculation for the number of cells in a bacterial population after $$n$$ generations, starting from $$N_0$$ cells?

Accepted Answer

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

Question 4

Which of the following best explains why nitrogen is essential for bacterial growth?

Accepted Answer

It is a major component of nucleic acids and proteins.

Question 5

A culture medium that contains only known amounts of pure chemicals is best described as:

Accepted Answer

Defined medium

Question 6

Which of the following is a direct method for measuring microbial growth?

Accepted Answer

Counting colonies on an agar plate (CFU method)

Question 7

A patient with a compromised immune system is at risk for infection from which type of microorganism?

Accepted Answer

Opportunistic pathogen

Question 8

Which of the following best describes the stationary phase of bacterial growth?

Accepted Answer

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

Question 9

Which of the following relationships is an example of commensalism?

Accepted Answer

One organism benefits, the other is unaffected.

Question 10

A bacterium that grows best at 4°C but can also grow at 20°C is classified as a:

Accepted Answer

Psychrophile

Question 11

Which of the following best describes the function of a selective medium?

Accepted Answer

It inhibits the growth of some organisms while allowing others to grow.

Question 12

Which of the following is a correct statement about quorum sensing in biofilms?

Accepted Answer

It involves the production and detection of signaling molecules to coordinate gene expression.

Question 13

Which of the following best describes the effect of hypertonic environments on bacterial cells?

Accepted Answer

Cells will lose water and undergo plasmolysis.

Question 14

A microbiologist wants to isolate a pure culture from a mixed sample. Which technique is most appropriate?

Accepted Answer

Streak plate method

Question 15

Which of the following is a reason why oxygen can be toxic to some microorganisms?

Accepted Answer

Oxygen can form reactive oxygen species that damage cellular components.

Question 16

Which of the following best describes the difference between arithmetic and logarithmic growth?

Accepted Answer

Arithmetic growth is linear, while logarithmic growth is exponential.

Question 17

A culture starts with 100 cells. After 5 generations, how many cells will there be? Use the formula $$N = N_0$ 	imes 2^n.$$

Accepted Answer

320

Question 18

Which of the following is NOT a typical limiting factor for bacterial growth in a laboratory culture?

Accepted Answer

Presence of eukaryotic cells

Question 19

Which of the following best describes a differential medium?

Accepted Answer

A medium that contains substances that cause some bacteria to take on an appearance that distinguishes them from others.

Question 20

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

Accepted Answer

Lag phase, log phase, stationary phase, death phase

Microbial Classification, Growth, and Laboratory Techniques: Study Guide

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