Question 1

Which component of the prokaryotic flagellum acts as the rotary motor, enabling bacterial movement by utilizing the proton motive force?

Accepted Answer

Basal body

Question 2

A bacterium is exposed to a gradient of an attractant. Which sequence of flagellar rotation and movement best describes its behavior as it moves toward the attractant?

Accepted Answer

Predominantly CCW rotation, resulting in longer runs toward the attractant

Question 3

Which structure is primarily responsible for the transfer of genetic material between bacterial cells during conjugation?

Accepted Answer

Sex pilus

Question 4

Which of the following best describes the difference in peptidoglycan structure between Gram-positive and Gram-negative bacteria?

Accepted Answer

Gram-positive bacteria have a thick peptidoglycan layer with teichoic acids, while Gram-negative bacteria have a thin peptidoglycan layer located between the inner and outer membranes

Question 5

Which component of the lipopolysaccharide (LPS) layer is responsible for the toxic effects observed in Gram-negative bacterial infections?

Accepted Answer

Lipid A

Question 6

A scientist is studying the periplasmic space of a Gram-negative bacterium. Which of the following would NOT be found in the periplasm?

Accepted Answer

Ribosomes

Question 7

Which statement correctly distinguishes the nucleoid of a prokaryotic cell from a eukaryotic nucleus?

Accepted Answer

The nucleoid is an irregular region containing circular DNA without a surrounding membrane

Question 8

Which equation best represents the composition of a prokaryotic ribosome?

Accepted Answer

$$70S = 50S + 30S$$

Question 9

A bacterium stores polyphosphate, sulfur, and glycogen in its cytoplasm. What is the primary advantage of these storage granules?

Accepted Answer

They provide reserves of nutrients and energy for survival during scarcity

Question 10

Which of the following statements about endospores is TRUE?

Accepted Answer

Endospores are dormant, highly resistant structures formed for survival

Question 11

Why are Gram-negative cell walls considered more protective than Gram-positive cell walls, despite having a thinner peptidoglycan layer?

Accepted Answer

The outer membrane and LPS layer in Gram-negative bacteria act as barriers to antibiotics and harmful substances

Question 12

Motile, chemotactic bacteria are considered sensory and memory cells because:

Accepted Answer

They detect chemical gradients and compare past and present concentrations to guide movement

Question 13

Which equation correctly represents the composition of a eukaryotic ribosome?

Accepted Answer

$$80S = 60S + 40S$$

Question 14

Why are endospores not considered reproductive or multiplication structures?

Accepted Answer

Endospore formation does not increase cell number; one cell forms one spore, which later becomes one cell

Question 15

Which condition can destroy endospores, despite their extreme resistance?

Accepted Answer

Autoclaving at $$121\ ^\circ \mathrm{C}$$, 15 psi, for 15 minutes

Question 16

What are the names of the two processes: (a) formation of a spore from a vegetative cell, and (b) formation of a vegetative cell from a spore?

Accepted Answer

(a) Sporulation, (b) Germination

Question 17

How did the presence of endospores contribute to the early controversy over spontaneous generation of microbes?

Accepted Answer

Endospores caused microbes to appear after boiling, falsely supporting spontaneous generation

Question 18

A Gram-negative bacterium is exposed to an antibiotic that targets peptidoglycan. Which cell envelope feature may help it resist the antibiotic?

Accepted Answer

Outer membrane with LPS and porins

Question 19

Which of the following is NOT a substance commonly stored in bacterial inclusion bodies?

Accepted Answer

DNA

Question 20

Which protein forms the filament of the prokaryotic flagellum?

Accepted Answer

Flagellin

Microbiology Study Guide: Prokaryotic Cell Structure, Function, and Adaptation

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