Q: A culture of E. coli doubles every 20 minutes. If you start with 1,000 cells, how many cells will there be after 1 hour? Use the formula $$N = N_0$ \times 2$$^{n}$$, where n$ is the number of generations.

$$N = 1,000 \times 2$$^{3}$$ = 8,000$$

Question 1

Which microbial growth phase in a closed batch culture is characterized by the highest rate of genome replication?

Accepted Answer

Log (Exponential) phase

Question 2

A microbiologist wants to culture a bacterium that grows best at 37°C and is commonly found in human hosts. Which temperature category does this bacterium belong to?

Accepted Answer

Mesophile

Question 3

Which of the following statements about binary fission is correct?

Accepted Answer

It results in two genetically identical cells.

Question 4

A bacterium is classified as a halophile. Which environment would best support its growth?

Accepted Answer

A salt-saturated pond

Question 5

Which of the following is TRUE regarding endospores?

Accepted Answer

They are metabolically inactive and can withstand harsh conditions.

Question 6

A microbiologist uses a medium containing yeast extract and tryptone to culture bacteria. What type of medium is this?

Accepted Answer

Complex medium

Question 7

Which method would best allow a researcher to visually distinguish between two bacterial species based on colony color?

Accepted Answer

Differential media

Question 8

A culture of E. coli doubles every 20 minutes. If you start with 1,000 cells, how many cells will there be after 1 hour? Use the formula $$N = N_0$ 	imes 2$$^{n}$$, where n$ is the number of generations.

Accepted Answer

$$N = 1,000 	imes 2$$^{3}$$ = 8,000$$

Question 9

Which physical method is most effective for sterilizing heat-sensitive liquid media?

Accepted Answer

Membrane filtration

Question 10

A bacterium grows only in the presence of oxygen and dies in its absence. How is it classified?

Accepted Answer

Obligate aerobe

Question 11

Which microbial control strategy is defined as eliminating all forms of microbial life, including endospores?

Accepted Answer

Sterilization

Question 12

A researcher wants to measure the metabolic activity of a bacterial culture as an indirect method of estimating cell numbers. Which of the following would NOT be an appropriate indirect method?

Accepted Answer

Plate count

Question 13

Which of the following best describes a biofilm?

Accepted Answer

A community of microbes attached to a surface and encased in a matrix

Question 14

Which type of germicide would you use to disinfect surgical instruments that must be free of all microbes, including endospores?

Accepted Answer

High-level germicide

Question 15

A microbe is classified as a phototroph. What is its primary energy source?

Accepted Answer

Light

Question 16

Which of the following is TRUE about selective media?

Accepted Answer

It favors the growth of specific microbes while inhibiting others.

Question 17

A bacterium grows in both the presence and absence of oxygen, but prefers oxygen for optimal growth. How is it classified?

Accepted Answer

Facultative anaerobe

Question 18

Which of the following best describes the function of a HEPA filter?

Accepted Answer

Removes microbes from air

Question 19

A scientist is culturing Streptomyces, which reproduces by spore formation. Which statement is correct regarding its reproduction?

Accepted Answer

It forms metabolically inactive spores that can survive harsh conditions.

Question 20

A bacterial culture is grown in a batch system. After a period of rapid cell division, nutrients become depleted and waste accumulates. Which phase is the culture entering?

Accepted Answer

Stationary phase

Fundamentals of Microbial Growth: Study Guide

Study Guide - Practice Questions

Study Guide - Flashcards