Question 1

Which of the following best explains why the hanging drop technique is preferred over the wet mount for observing true motility in microorganisms?

Accepted Answer

It prevents the microorganisms from being compressed, allowing for more natural movement.

Question 2

A student observes random, erratic movement of small particles in a wet mount. Which phenomenon is most likely being observed, and what is its primary cause?

Accepted Answer

Brownian movement caused by collisions with water molecules.

Question 3

Why is petroleum jelly used when preparing a hanging drop slide?

Accepted Answer

To seal the coverslip and reduce evaporation of the drop.

Question 4

Which of the following is a disadvantage of using a wet mount compared to a hanging drop preparation?

Accepted Answer

Wet mounts are more likely to cause evaporation and compression of the sample.

Question 5

Which of the following statements about Brownian movement is correct?

Accepted Answer

It is random and results from collisions with fluid molecules.

Question 6

Why should oil immersion lenses NOT be used with the hanging drop technique?

Accepted Answer

Oil can disrupt or collapse the hanging drop, altering organism behavior.

Question 7

Which of the following best describes the effect of alcohol on motile microorganisms during microscopic observation?

Accepted Answer

Alcohol disrupts cell membranes, reducing or stopping motility.

Question 8

A microbiologist wants to observe the budding of yeast cells. Which magnification and technique would be most appropriate?

Accepted Answer

400× brightfield microscopy with a wet mount.

Question 9

Which of the following is a key difference between prokaryotic and eukaryotic cells?

Accepted Answer

Prokaryotes have a single, circular DNA molecule; eukaryotes have multiple, linear chromosomes.

Question 10

A sample contains both bacteria and protozoa. Which magnification would best allow you to observe both types of organisms in a wet mount?

Accepted Answer

400×

Question 11

Which of the following equations best describes the relationship between diffusion rate ($$D$$), temperature ($$T$$), and particle size ($$r) in $$Brownian motion, according to the Stokes-Einstein equation?

Accepted Answer

$$D = \frac{kT}{6\pi \eta r}$$

Question 12

Which of the following bacteria is most commonly associated with urinary tract infections, as shown in the provided diagram?

Accepted Answer

Escherichia coli

Question 13

A student prepares a wet mount but finds it difficult to see bacteria. What is the most likely reason?

Accepted Answer

Bacteria are nearly transparent and blend into the background.

Question 14

Which of the following steps is essential for preparing a hanging drop slide, as shown in the procedure diagram?

Accepted Answer

Applying a ring of petroleum jelly around the concavity of the depression slide.

Question 15

Which of the following is NOT a reason for using the hanging drop method to observe microorganisms?

Accepted Answer

To increase the contrast by staining the organisms.

Question 16

Which of the following organisms would require electron microscopy for visualization due to its size?

Accepted Answer

Viruses

Question 17

Which of the following best describes the effect of iodine on motile microorganisms?

Accepted Answer

Iodine denatures proteins, inactivating flagella and stopping motility.

Question 18

Which of the following is a common misconception when distinguishing between Brownian movement and true motility?

Accepted Answer

True motility involves directional movement, while Brownian movement is random.

Question 19

Which of the following is a correct step in the procedure for preparing a hanging drop slide, as shown in the diagram?

Accepted Answer

Place a loopful of bacterial culture in the center of the coverslip.

Question 20

Which of the following best explains why the hanging drop method provides a more accurate observation of microbial motility than the wet mount?

Accepted Answer

It prevents compression and allows movement in three dimensions.

Microscopy Techniques for Observing Living Microorganisms

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