Question 1

Which metric unit is most commonly used to measure bacterial cell size in microscopy?

Accepted Answer

Micrometer ($$\mum)$$

Question 2

Which two factors primarily determine the resolving power of a microscope?

Accepted Answer

Wavelength of radiation and numerical aperture

Question 3

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

Accepted Answer

$$40 	imes 10 = 400$$

Question 4

Why does oil immersion increase the resolution of a light microscope?

Accepted Answer

Oil prevents light from being refracted away from the specimen

Question 5

Which microscopy technique is best for observing pale, unstained specimens against a dark background?

Accepted Answer

Dark-field microscopy

Question 6

What is the main advantage of phase contrast microscopy over bright-field microscopy?

Accepted Answer

It allows visualization of living, unstained cells

Question 7

In fluorescence microscopy, what is the role of fluorophores?

Accepted Answer

They absorb photon energy and emit light at a longer wavelength

Question 8

Which staining procedure would you use to differentiate between Gram-positive and Gram-negative bacteria?

Accepted Answer

Gram stain

Question 9

Why do Gram-positive bacteria retain the crystal violet stain and appear purple after Gram staining?

Accepted Answer

They have a thick peptidoglycan layer that traps the dye

Question 10

A sputum sample is stained and shows acid-fast bacilli. What does this indicate?

Accepted Answer

Presence of mycobacterial infection

Question 11

Which type of stain would you use to visualize bacterial capsules?

Accepted Answer

Negative stain

Question 12

What is the primary function of fixing cells to a slide before staining?

Accepted Answer

To preserve cell morphology and adhere cells to the slide

Question 13

Which of the following stains is a basic (cationic) dye commonly used in simple staining?

Accepted Answer

Crystal violet

Question 14

During the Schaeffer-Fulton endospore staining procedure, what is the role of heat?

Accepted Answer

It helps malachite green penetrate the tough spore wall

Question 15

Which microscopy technique would you use to obtain a highly detailed image of the internal structure of a virus?

Accepted Answer

Transmission Electron Microscopy (TEM)

Question 16

A sample is stained with methylene blue and observed under a microscope. What type of information can be obtained from this simple stain?

Accepted Answer

Cell shape, size, and arrangement

Question 17

Which of the following best describes the difference between SEM and TEM?

Accepted Answer

SEM provides 3D images of surfaces, TEM provides detailed internal images

Question 18

Why do acid-fast bacteria resist decolorization by acid alcohol during staining?

Accepted Answer

They have a thick, waxy layer of mycolic acid in their cell walls

Question 19

Which staining method would you use to visualize bacterial flagella?

Accepted Answer

Flagella stain

Question 20

A researcher wants to identify the presence of a specific protein on the surface of immune cells. Which microscopy and staining technique should they use?

Accepted Answer

Immunofluorescence microscopy with antibodies conjugated to a fluorophore

Microscopy, Staining, and Classification: Principles and Applications in Microbiology

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