Question 1

Which of the following best describes the function of a bacterial capsule?

Accepted Answer

It protects the cell from phagocytosis and helps form biofilms.

Question 2

During endospore formation, which adaptation is MOST responsible for the resistance of endospores to harsh environmental conditions?

Accepted Answer

Presence of dipicolinic acid and calcium ions ($$Ca^{2+})$$

Question 3

A bacterium is observed to have flagella distributed all over its surface. What is the term for this arrangement?

Accepted Answer

Peritrichous

Question 4

Which statement correctly contrasts bacterial and archaeal flagella?

Accepted Answer

Bacterial flagella are composed of flagellin, while archaeal flagella (archaellum) are composed of different proteins and are assembled at the base.

Question 5

Which of the following is NOT a function of the extracellular polymeric substance (EPS) in biofilms?

Accepted Answer

Acts as a site for flagellar assembly

Question 6

A Gram-negative bacterium is observed to move in a series of 'runs' and 'tumbles.' What is the underlying mechanism for this movement?

Accepted Answer

Flagellar motor alternates between counterclockwise and clockwise rotation, causing smooth runs and abrupt tumbles.

Question 7

Which of the following best explains why endospores are considered the most resistant cellular structures?

Accepted Answer

They contain dipicolinic acid, $$Ca^{2+}$$, and small acid-soluble proteins (SASPs) that protect DNA.

Question 8

Which of the following surface structures is MOST associated with twitching motility?

Accepted Answer

Type IV pili

Question 9

A bacterium moves toward a chemical attractant using a biased random walk. What does this mean?

Accepted Answer

The bacterium alternates between runs and tumbles, with longer runs in the direction of increasing attractant concentration.

Question 10

Which of the following is TRUE regarding the assembly of bacterial flagella?

Accepted Answer

Flagellin subunits are transported through a central channel and added at the tip of the flagellum.

Question 11

Which of the following is a distinguishing feature of a bacterial slime layer compared to a capsule?

Accepted Answer

Slime layers are unorganized and loosely attached, while capsules are organized and tightly attached.

Question 12

Which of the following is NOT a step in bacterial endospore formation?

Accepted Answer

Assembly of flagella

Question 13

A patient is infected with Bacillus anthracis. Which property of this bacterium's endospores makes it particularly dangerous in bioterrorism scenarios?

Accepted Answer

Extreme resistance to heat, chemicals, and desiccation

Question 14

Which equation best represents the proton motive force ($$PMF) $$that powers bacterial flagellar rotation?

Accepted Answer

$$PMF = \Delta \Psi - (2.303 \frac{RT}{F} \Delta pH)$$

Question 15

Which of the following is a real-world consequence of capsule production in pathogenic bacteria?

Accepted Answer

Enhanced ability to evade host immune responses

Question 16

Which of the following statements about gliding motility is CORRECT?

Accepted Answer

It involves movement over solid surfaces using slime layers or specific proteins.

Question 17

Which bacterial structure is MOST immunogenic and used to distinguish serovars such as E. coli O157:H7?

Accepted Answer

Flagella (H antigen)

Question 18

A bacterium is exposed to a repellent. How does its motility change?

Accepted Answer

It increases the frequency of tumbles to change direction away from the repellent.

Question 19

Which of the following is TRUE regarding the difference between vegetative cells and endospores?

Accepted Answer

Vegetative cells have high water content and are metabolically active, while endospores have low water content and are metabolically dormant.

Question 20

Which of the following mechanisms allows bacteria to move over solid surfaces in the absence of flagella?

Accepted Answer

Gliding motility using slime layers or type IV pili

Cell Surface Structures and Motility in Microbiology

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