Question 1

Which of the following units is most appropriate for measuring the size of a typical bacterial cell?

Accepted Answer

Micrometer ($$1\ \mu m)$$

Question 2

A compound light microscope has an objective lens with 40x magnification and an ocular lens with 10x magnification. What is the total magnification?

Accepted Answer

$$40 	imes 10 = 400$$

Question 3

Which microscopy technique would be most suitable for observing live, unstained, and thin microorganisms such as spirochetes?

Accepted Answer

Darkfield microscopy

Question 4

What is the main advantage of using immersion oil with a high-power objective lens?

Accepted Answer

It reduces light refraction and increases resolution.

Question 5

Which of the following best describes the path of light in a compound microscope?

Accepted Answer

Light source → condenser lens → specimen → objective lens → body tube → ocular lens → eye

Question 6

Which microscopy technique uses two beams of light and prisms to produce brightly colored, three-dimensional images?

Accepted Answer

Differential interference contrast (DIC) microscopy

Question 7

A researcher wants to visualize the location of a specific protein within a bacterial cell using antibodies. Which microscopy technique should they use?

Accepted Answer

Fluorescence microscopy with immunofluorescence

Question 8

Which of the following statements about electron microscopy is TRUE?

Accepted Answer

Electron microscopes can resolve structures as small as 0.2 nm.

Question 9

Which type of microscopy would be best for studying the surface structure of a virus particle in three dimensions?

Accepted Answer

Scanning electron microscopy (SEM)

Question 10

Which of the following stains would be most appropriate for distinguishing between Mycobacterium tuberculosis and Staphylococcus aureus in a clinical sample?

Accepted Answer

Acid-fast stain

Question 11

What is the primary difference between a basic dye and an acidic dye in bacterial staining?

Accepted Answer

Basic dyes have a positively charged chromophore; acidic dyes have a negatively charged chromophore.

Question 12

During the Gram stain procedure, what color will a Gram-negative cell appear after the decolorizing step but before the counterstain?

Accepted Answer

Colorless

Question 13

Which of the following best explains why a mordant is sometimes used in staining procedures?

Accepted Answer

To increase the affinity of the stain for the specimen

Question 14

A scientist wants to observe the movement of proteins within a living cell in real time, up to 1 mm deep. Which microscopy technique should they use?

Accepted Answer

Two-photon microscopy

Question 15

Which of the following is a key advantage of scanning probe microscopy (such as STM or AFM) over electron microscopy?

Accepted Answer

It can be used to view live specimens in their natural state.

Question 16

Which of the following best describes negative staining?

Accepted Answer

Staining the background with an acidic dye

Question 17

Which of the following is the correct order of steps in the Gram stain procedure?

Accepted Answer

Crystal violet → Gram’s iodine → Alcohol/acetone → Safranin

Question 18

Which special stain would be most appropriate for visualizing the presence of a bacterial capsule?

Accepted Answer

Capsule stain

Question 19

A sample is stained with carbolfuchsin, decolorized with acid-alcohol, and counterstained with methylene blue. Acid-fast bacteria will appear:

Accepted Answer

Red

Question 20

Which microscopy technique is most suitable for mapping the atomic and molecular shapes of a specimen without modifying it?

Accepted Answer

Scanning probe microscopy

Microscopy in Microbiology: Principles, Types, and Applications

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