Q: If a microscope has a numerical aperture ($$NA) of 1.25 $$and uses light of wavelength $$\lambda = 500 nm$$, what is the theoretical resolution limit?

$$R = \frac{500}{2 \times 1.25} = 200 nm$$

Question 1

Which property of a microscope determines its ability to distinguish two close objects as separate entities?

Accepted Answer

Resolution

Question 2

A student is using a compound brightfield microscope with a 10x eyepiece and a 40x objective lens. What is the total magnification achieved?

Accepted Answer

$$10 	imes 40 = 400$$

Question 3

Which type of microscopy is best suited for viewing internal structures of living cells without staining?

Accepted Answer

Phase-contrast microscopy

Question 4

Why can't viruses be seen with a typical light microscope?

Accepted Answer

Viruses are smaller than the resolution limit of light microscopes

Question 5

Which equation correctly represents the relationship between resolution ($$R$$), wavelength ($$\lambda$$), and numerical aperture ($$NA) in $$microscopy?

Accepted Answer

$$R = \frac{\lambda}{2NA}$$

Question 6

A researcher wants to study the surface features of a bacterial cell. Which microscopy technique should they use?

Accepted Answer

Scanning electron microscopy (SEM)

Question 7

What is the main advantage of fluorescence microscopy over brightfield microscopy?

Accepted Answer

It can specifically label and identify molecules or microbes using fluorescent dyes

Question 8

Which staining technique is used to differentiate bacteria based on the amount of peptidoglycan in their cell walls?

Accepted Answer

Gram stain

Question 9

A sample is stained with Auramine O and observed under a fluorescence microscope. What is the most likely organism being detected?

Accepted Answer

Mycobacterium tuberculosis

Question 10

Which of the following best describes the principle of refraction in microscopy?

Accepted Answer

Light changing direction as it enters a new medium

Question 11

A scientist needs to visualize the 3D structure of a bacterial cell with high resolution. Which microscopy technique should they use?

Accepted Answer

Confocal microscopy

Question 12

Which type of dye stains the background rather than the bacteria, making the cells appear clear against a dark background?

Accepted Answer

Negative dye

Question 13

What is the main purpose of an endospore stain in microbiology?

Accepted Answer

To identify bacteria capable of surviving harsh conditions

Question 14

Which microscopy technique requires the specimen to be either naturally fluorescent or labeled with a fluorophore?

Accepted Answer

Fluorescence microscopy

Question 15

A microbiologist wants to observe the movement of bacteria. Which stain would be most useful?

Accepted Answer

Flagella stain

Question 16

Which of the following is a differential stain used to identify acid-fast bacteria such as Mycobacterium tuberculosis?

Accepted Answer

Acid-fast stain

Question 17

If a microscope has a numerical aperture ($$NA) of 1.25 $$and uses light of wavelength $$\lambda = 500 nm$$, what is the theoretical resolution limit?

Accepted Answer

$$R = \frac{500}{2 	imes 1.25} = 200 nm$$

Question 18

Which of the following statements about electron microscopy is correct?

Accepted Answer

It can resolve structures much smaller than those seen with light microscopy

Question 19

Why is staining often necessary when using a brightfield microscope to observe bacteria?

Accepted Answer

Most bacteria are transparent and difficult to see without staining

Question 20

Which of the following best explains the concept of numerical aperture in microscopy?

Accepted Answer

The ability of a lens to gather light

Microscopy: Principles and Applications in Anatomy & Physiology

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