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 sporulation, which adaptation makes endospores highly resistant to harsh environmental conditions?

Accepted Answer

Accumulation of dipicolinic acid and Ca$$^{2+}$$ ions.

Question 3

Which arrangement of flagella is described as having flagella distributed all over the surface of the cell?

Accepted Answer

Peritrichous

Question 4

What is the main structural difference between Gram-negative and Gram-positive bacterial flagella?

Accepted Answer

Gram-negative flagella have an additional outer membrane ring.

Question 5

Which statement correctly compares archaeal and bacterial flagella?

Accepted Answer

Archaeal flagella are composed of different proteins and are structurally distinct from bacterial flagella.

Question 6

A bacterium exhibits 'run and tumble' motility. What causes a 'tumble'?

Accepted Answer

Flagellar bundle comes apart as the motor rotates clockwise.

Question 7

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

Accepted Answer

Serves as the main site for flagellar assembly.

Question 8

Which protein forms the filament of bacterial flagella?

Accepted Answer

Flagellin

Question 9

What is the primary energy source for the rotation of bacterial flagella?

Accepted Answer

Proton motive force ($$\Delta p)$$

Question 10

Which mechanism allows bacteria to move over solid surfaces independently of flagella?

Accepted Answer

Twitching motility via type IV pili

Question 11

A patient is infected with Bacillus anthracis. Which property of its endospores contributes most to its persistence in the environment?

Accepted Answer

Resistance to heat, chemicals, and desiccation

Question 12

Which of the following best explains how bacteria perform chemotaxis toward an attractant?

Accepted Answer

They bias their random walk by increasing the length of runs when moving up the attractant gradient.

Question 13

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.

Question 14

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

Accepted Answer

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

Question 15

Which bacterial structure is most likely to contribute to virulence by preventing phagocytosis?

Accepted Answer

Capsule

Question 16

A bacterium is observed to move like a corkscrew through viscous environments. Which structure is responsible for this type of motility?

Accepted Answer

Periplasmic flagella (axial filaments) in spirochetes

Question 17

Which of the following statements about endospores is correct?

Accepted Answer

Endospores contain small acid-soluble proteins (SASPs) that protect DNA.

Question 18

Which of the following is a real-world consequence of bacterial biofilm formation?

Accepted Answer

Enhanced resistance to environmental stress and host immune responses.

Question 19

A researcher is studying a bacterium that moves by gliding. Which of the following is most likely involved in this process?

Accepted Answer

Type IV pili and gliding-specific proteins

Question 20

Which equation best represents the proton motive force ($$\Delta p) $$that powers bacterial flagella?

Accepted Answer

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

Cell Surface Structures and Motility in Microbiology

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