$$g = \frac{120\ \text{minutes}}{6\ \text{generations}} = 20\ \text{minutes}$$

Question 1

Which of the following statements best explains why viruses are considered exceptions to the classic definition of a microorganism?

Accepted Answer

Viruses are not considered living because they lack key characteristics of life.

Question 2

A scientist isolates a microorganism from a saline lake with a pH of 10. Which adaptations would you expect this organism to possess?

Accepted Answer

Diether lipids and Na+/H+ antiporters.

Question 3

Which of the following is a major advantage of small cell size in prokaryotes?

Accepted Answer

Small cells support greater nutrient exchange per unit cell volume, leading to faster growth rates.

Question 4

Which of the following best describes the structure of a bacterial cell wall?

Accepted Answer

It is made of peptidoglycan, a polymer of peptide-linked chains of amino sugars.

Question 5

A Gram-negative bacterium is most likely to possess which of the following envelope components?

Accepted Answer

An outer membrane containing lipopolysaccharide (LPS).

Question 6

Which specialized bacterial structure is responsible for motility and chemotaxis?

Accepted Answer

Flagella

Question 7

A mutant strain of bacteria can swim but no longer moves toward a food source. Which cellular structure is most likely affected?

Accepted Answer

Chemoreceptor

Question 8

Which equation correctly represents the calculation for the growth rate constant ($$k) in $$bacterial cultures?

Accepted Answer

$$k = \frac{n}{t}$$

Question 9

If a culture of E. coli grows for 2 hours and produces 6 generations, what is the generation time ($$g) in $$minutes?

Accepted Answer

$$g = \frac{120\ 	ext{minutes}}{6\ 	ext{generations}} = 20\ 	ext{minutes}$$

Question 10

Which of the following media types would best allow you to distinguish between two bacterial species based on their ability to ferment lactose?

Accepted Answer

Differential medium

Question 11

Which method of bacterial quantification does NOT differentiate between living and dead cells?

Accepted Answer

Optical density

Question 12

Which adaptation would you expect in a bacterium living in a cold environment?

Accepted Answer

Cis-unsaturated fatty acids

Question 13

Which of the following is a function of the bacterial capsule?

Accepted Answer

Prevents phagocytosis by host immune cells.

Question 14

Which of the following is an example of a physical agent used to control microbial growth?

Accepted Answer

Pasteurization

Question 15

Which extremophile would most likely be found in a hot spring with temperatures above 90°C?

Accepted Answer

Hyperthermophile

Question 16

Which of the following differentiated states is metabolically dormant?

Accepted Answer

Spore

Question 17

A bacterium is found to grow best at pH 2. Which adaptation is most likely present?

Accepted Answer

Tetraether lipids and proton extrusion mechanisms.

Question 18

Which of the following mutations in the toxin/antitoxin system would prevent bacteria from dying from programmed cell death?

Accepted Answer

Deletion of mazF from the genome

Question 19

Which of the following is a reason why most bacteria are unculturable in the laboratory?

Accepted Answer

They require specific growth factors not provided in standard media.

Microbiology: Foundations, Cell Structure, Growth, and Environmental Influences

Study Guide - Practice Questions