Question 1

Which type of flagellar arrangement is characterized by a single flagellum located at one end of the bacterium?

Accepted Answer

Monotrichous

Question 2

In the motility medium (MTM) with TTC, what does the appearance of a red color indicate?

Accepted Answer

The reduction of TTC to formazan by growing bacteria

Question 3

A student observes a tube of MTM with TTC that shows red color only along the stab line. What does this result indicate?

Accepted Answer

The organism is nonmotile

Question 4

Which of the following best describes the difference between Brownian motion and true motility?

Accepted Answer

Brownian motion is random movement due to water molecules, while true motility is self-propelled movement by the organism

Question 5

Why is it difficult to observe unstained bacteria in a wet mount preparation?

Accepted Answer

Their refractive index is similar to water, making them nearly transparent

Question 6

Which organism would you expect to show a diffuse red color throughout the MTM with TTC after incubation?

Accepted Answer

Pseudomonas aeruginosa

Question 7

A microbiology student inoculates a motility medium with an unknown bacterium. After incubation, the tube shows growth only along the stab line with no spreading. Which of the following is the most likely explanation?

Accepted Answer

The bacterium is nonmotile

Question 8

Which of the following best explains why Bacillus cereus should not be inoculated into MTM for motility testing?

Accepted Answer

It only grows on the surface due to its aerobic nature

Question 9

If a student observes a motility medium tube with a red color radiating outward from the stab line, what does this indicate about the organism?

Accepted Answer

It is motile

Question 10

Which of the following is the correct sequence of steps for preparing a wet mount to observe bacterial motility?

Accepted Answer

Place a drop of broth on a slide, cover with a coverslip, focus using the microscope

Question 11

Which of the following best describes the function of TTC in motility medium?

Accepted Answer

It is reduced by growing bacteria to form a red pigment, indicating bacterial growth

Question 12

A tube of motility medium is inoculated and incubated. After 24 hours, the medium remains clear with no red color. What is the most likely explanation?

Accepted Answer

No bacterial growth occurred

Question 13

Which of the following statements about the use of a microscope to observe bacterial motility in a wet mount is correct?

Accepted Answer

Adjusting the diaphragm improves contrast for observing unstained bacteria

Question 14

Which of the following equations best represents the reduction of TTC to formazan in the motility test?

Accepted Answer

$$\mathrm{TTC} + 2e^- + 2H^+ \rightarrow \mathrm{Formazan}$$

Question 15

A microbiologist is testing two organisms: one shows spreading red color in MTM, and the other shows only a red line along the stab. Which is the most likely identification?

Accepted Answer

Motile: Pseudomonas aeruginosa; Nonmotile: Staphylococcus aureus

Question 16

Which of the following best explains why only a small drop or 2 loopfuls of broth should be used when preparing a wet mount?

Accepted Answer

To avoid making the preparation too thick to observe individual bacteria

Question 17

Which of the following is NOT a correct flagellar arrangement?

Accepted Answer

Polytichous

Question 18

A student accidentally uses too much broth when preparing a wet mount. What is the most likely consequence?

Accepted Answer

The preparation will be too thick, making it difficult to focus and observe motility

Question 19

Which of the following best describes the appearance of a motile organism in MTM with TTC after incubation?

Accepted Answer

Red color radiating outward from the stab line

Question 20

Why is it important to discard used slides in stainless steel containers after viewing wet mounts?

Accepted Answer

To prevent contamination and ensure safe disposal of biohazardous material

Determining Bacterial Motility: Methods and Interpretation

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