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

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 correct 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

Providing energy for flagellar rotation

Question 6

A Gram-negative bacterium moves toward a nutrient source using 'run and tumble' behavior. What is the underlying mechanism for this movement?

Accepted Answer

Flagellar motor rotates counterclockwise during runs and clockwise during 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 surface structure is most directly involved in twitching motility across solid surfaces?

Accepted Answer

Type IV pili

Question 9

A bacterium is exposed to a repellent. How does its 'biased random walk' change?

Accepted Answer

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

Question 10

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

Accepted Answer

Capsules are neatly organized and firmly attached to the cell wall.

Question 11

Which process is most directly responsible for the assembly of flagellin subunits in bacterial flagella?

Accepted Answer

Flagellin is transported through a channel and added at the tip of the flagellum.

Question 12

Which of the following is TRUE regarding the energy source for bacterial flagellar rotation?

Accepted Answer

It is powered by the proton motive force ($$\Delta p) $$across the cytoplasmic membrane.

Question 13

Which of the following statements about endospore formation is correct?

Accepted Answer

Endospore formation involves the activation of over 200 genes and results in a dormant, highly resistant cell.

Question 14

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

Accepted Answer

Flagella (H antigen)

Question 15

A patient is infected with Bacillus anthracis. Which adaptation allows this bacterium to survive extreme conditions and remain infectious for years?

Accepted Answer

Formation of endospores containing dipicolinic acid and SASPs

Question 16

Which of the following is a key difference between gliding motility and flagellar motility in bacteria?

Accepted Answer

Gliding motility is independent of flagella and often involves surface proteins or slime layers.

Question 17

Which of the following best describes the role of small acid-soluble proteins (SASPs) in endospores?

Accepted Answer

They protect spore DNA from damage by UV light and chemicals.

Question 18

A bacterium exhibits monotrichous flagellation. What does this mean?

Accepted Answer

It has a single flagellum at one end of the cell.

Question 19

Which of the following is a correct sequence of events during bacterial chemotaxis toward an attractant?

Accepted Answer

Chemoreceptors detect attractant $$\rightarrow$$ flagellar motor rotates counterclockwise $$\rightarrow$$ longer runs

Question 20

Which of the following is NOT a characteristic of bacterial endospores compared to vegetative cells?

Accepted Answer

Endospores have high metabolic activity and rapid growth.

Cell Surface Structures and Motility in Microbiology

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