Generation time = $$\frac{\text{Growth time (in minutes)}}{\text{Number of generations}}$$

Question 1

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

Accepted Answer

An asexual process where a single cell divides into two identical cells

Question 2

A batch culture of E. coli is grown for 80 minutes. If the generation time is 20 minutes, how many generations have occurred?

Accepted Answer

Generation number = $$\frac{80}{20} = 4$$

Question 3

Which phase of bacterial growth is characterized by cells adjusting to their environment and not actively dividing?

Accepted Answer

Lag phase

Question 4

In a closed batch system, what happens during the stationary phase?

Accepted Answer

Population growth rate levels off as the number of cells dividing equals the number dying

Question 5

Which of the following microbes would most likely be found in a hot spring with temperatures above 80°C?

Accepted Answer

Extreme thermophiles

Question 6

A microbe that thrives in environments with a pH of 2 and uses proton pumps to maintain a neutral cytoplasmic pH is classified as:

Accepted Answer

Acidophile

Question 7

Which equation correctly calculates the generation time for bacteria?

Accepted Answer

Generation time = $$\frac{	ext{Growth time (in minutes)}}{	ext{Number of generations}}$$

Question 8

Which of the following is NOT a characteristic of biofilms?

Accepted Answer

Biofilms are difficult to treat and can form on indwelling devices

Question 9

Which type of media would you use to isolate a fastidious organism that requires multiple growth factors?

Accepted Answer

Complex media

Question 10

A bacterium that can grow in both the presence and absence of oxygen, switching between aerobic respiration and fermentation, is classified as:

Accepted Answer

Facultative anaerobe

Question 11

Which enzyme is responsible for converting superoxide ions to hydrogen peroxide in aerobic microbes?

Accepted Answer

Superoxide dismutase

Question 12

Halophiles are microbes that thrive in environments with:

Accepted Answer

High salt concentrations

Question 13

Which of the following best describes a chemoautotroph?

Accepted Answer

Uses chemical compounds for energy and inorganic carbon (CO2) for growth

Question 14

Which type of media is formulated to visually distinguish one microbe from another based on colony characteristics?

Accepted Answer

Differential media

Question 15

Why are hyperthermophiles that grow at temperatures above 100°C seemingly limited to oceanic depths?

Accepted Answer

Because oceanic depths have high pressure, preventing water from boiling at 100°C

Question 16

Which of the following is a real-world application of selective media?

Accepted Answer

Suppressing unwanted microbes and encouraging desired microbes in a urine sample

Question 17

A microbe that requires an external source of organic carbon for growth is classified as:

Accepted Answer

Heterotroph

Question 18

Which of the following is a plausible reason why primitive civilizations used food preservation techniques that rely on osmotic pressure?

Accepted Answer

High osmotic pressure inhibits microbial growth by causing plasmolysis

Question 19

Which of the following is a correct formula for calculating the total number of cells after n generations, starting from a single cell?

Accepted Answer

Total cells = $$2^n$$

Question 20

Which of the following is a method used to cultivate anaerobic bacteria?

Accepted Answer

Adding thioglycolate to media to convert $$O_2 to $$water

Microbial Growth and Cultivation: Physical and Chemical Requirements

Study Guide - Practice Questions