Question 1

Which of the following best describes the main difference between swimming and gliding motility in prokaryotes?

Accepted Answer

Swimming motility is powered by flagella rotation, while gliding motility involves movement along surfaces without the use of flagella.

Question 2

Which component of the bacterial flagellum is responsible for generating torque to rotate the flagellum?

Accepted Answer

The Mot proteins (stator)

Question 3

In Gram-negative bacteria, which sequence correctly lists the order of rings from the outside to the inside of the cell envelope in the flagellar basal body?

Accepted Answer

L ring, P ring, MS ring, C ring

Question 4

Which energy source drives the rotation of bacterial flagella?

Accepted Answer

Proton motive force

Question 5

A researcher observes a bacterium that moves in a smooth forward motion, then abruptly stops and jiggles before moving off in a new direction. What is this behavior called, and what is its biological significance?

Accepted Answer

Run and tumble; it allows the bacterium to randomly explore its environment and bias movement toward attractants.

Question 6

Which of the following best explains how peritrichously flagellated bacteria sense and respond to chemical gradients during chemotaxis?

Accepted Answer

They sense temporal changes in chemical concentration and adjust their run and tumble frequency accordingly.

Question 7

Which of the following is NOT a mechanism of gliding motility in bacteria?

Accepted Answer

Rotation of flagella in a liquid medium

Question 8

A mutant bacterium is unable to synthesize the Mot proteins. Which of the following would most likely be observed?

Accepted Answer

The bacterium would be unable to rotate its flagella and thus could not swim.

Question 9

Which of the following best describes the energy source for archaellar rotation in Archaea?

Accepted Answer

ATP hydrolysis

Question 10

A researcher wants to measure chemotaxis in a bacterial culture. Which experimental setup would best allow quantification of chemotactic response?

Accepted Answer

Inserting a capillary tube containing an attractant into a medium of motile bacteria and measuring the number of bacteria entering the tube.

Question 11

Which of the following statements about phototaxis is correct?

Accepted Answer

Phototaxis allows phototrophic organisms to optimize their position for harvesting light for photosynthesis.

Question 12

Which of the following best describes scotophobotaxis?

Accepted Answer

A behavioral response where cells tumble upon entering darkness and reverse direction to return to the light.

Question 13

Which of the following arrangements describes a bacterium with tufts of flagella at both poles?

Accepted Answer

Amphitrichous

Question 14

Which of the following is a correct statement about the synthesis of bacterial flagella?

Accepted Answer

The MS ring is assembled first and inserted into the cytoplasmic membrane.

Question 15

Which of the following best explains why flagellin amino acid sequences are highly conserved across bacterial species?

Accepted Answer

Flagellar motility is an ancient and essential function for many bacteria.

Question 16

A bacterium is observed to move toward a region of higher water concentration in a dry environment. Which type of taxis is this?

Accepted Answer

Hydrotaxis

Question 17

Which of the following is a key difference between bacterial flagella and archaeal archaella?

Accepted Answer

Bacterial flagella are composed of flagellin, while archaella are composed of several different proteins with little homology to flagellin.

Question 18

Which of the following best describes the function of chemoreceptors in bacterial chemotaxis?

Accepted Answer

They sense attractants or repellents and initiate a signaling cascade that affects flagellar rotation.

Question 19

A bacterium is placed in an environment with a gradient of increasing ionic strength. Which type of taxis would allow it to move toward or away from this gradient?

Accepted Answer

Osmotaxis

Question 20

Which of the following statements about twitching motility is correct?

Accepted Answer

Twitching motility involves the extension and retraction of type IV pili, powered by ATP hydrolysis.

Cell Locomotion and Chemotaxis in Prokaryotes

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