Question 1

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

Accepted Answer

It protects the cell from phagocytosis and helps in biofilm formation.

Question 2

Which arrangement of flagella is characterized by flagella distributed all over the surface of the cell?

Accepted Answer

Peritrichous

Question 3

During bacterial chemotaxis, what is the primary difference between a 'run' and a 'tumble'?

Accepted Answer

'Run' is a smooth forward motion; 'tumble' is a random change in direction due to flagellar bundle disruption.

Question 4

Which of the following adaptations makes bacterial endospores highly resistant to harsh environmental conditions?

Accepted Answer

Dipicolinic acid, calcium ions, and small acid-soluble proteins (SASPs)

Question 5

A bacterium is observed to move in a corkscrew-like fashion. Which structure is most likely responsible for this type of motility?

Accepted Answer

Periplasmic flagella (endoflagella) in spirochetes

Question 6

Which statement correctly compares bacterial and archaeal flagella?

Accepted Answer

Bacterial flagella are made of flagellin and assembled at the tip, while archaeal flagella (archaella) are assembled at the base and are structurally similar to type IV pili.

Question 7

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

Accepted Answer

Acts as a unique bacterial signature for immune recognition

Question 8

A Gram-negative bacterium is observed to have a single flagellum at each pole. What is the term for this flagellar arrangement?

Accepted Answer

Amphitrichous

Question 9

Which of the following best explains how the bacterial flagellum is powered?

Accepted Answer

By the proton motive force across the cytoplasmic membrane

Question 10

Which of the following is a key difference between a capsule and a slime layer?

Accepted Answer

Capsules are neatly organized and firmly attached; slime layers are unorganized and loosely attached.

Question 11

Which of the following events occurs during sporulation in Bacillus species?

Accepted Answer

Synthesis of dipicolinic acid and accumulation of calcium ions

Question 12

A patient is infected with a bacterium that forms biofilms on medical devices. Which surface structure is most likely involved in initial attachment to the device?

Accepted Answer

Capsule (glycocalyx)

Question 13

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

Accepted Answer

Gliding motility involving surface proteins or type IV pili

Question 14

Which of the following is a correct statement about the bacterial endospore compared to the vegetative cell?

Accepted Answer

Endospores are highly resistant to heat, chemicals, and radiation.

Question 15

Which protein is the main structural component of the bacterial flagellum?

Accepted Answer

Flagellin

Question 16

A bacterium exhibits 'biased random walk' in the presence of a chemical attractant. What does this mean?

Accepted Answer

The bacterium increases the length of runs when moving toward the attractant, resulting in a net movement toward higher concentrations.

Question 17

Which of the following equations best represents the proton motive force ($$\Delta p) $$that powers the bacterial flagellum?

Accepted Answer

$$\Delta p = \Delta \Psi - \frac{2.3RT}{F} \Delta pH$$

Question 18

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 19

Which of the following statements about type IV pili is correct?

Accepted Answer

They are involved in gliding and twitching motility by extending and retracting.

Question 20

A laboratory strain of E. coli is observed to have a mutation in its chemoreceptor proteins. What is the most likely effect on its motility?

Accepted Answer

It will lose the ability to sense attractants and repellents, resulting in random movement.

Cell Surface Structures and Motility in Microbiology

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