Q: If a specimen is 2 μm in diameter and is viewed under a microscope with a total magnification of 1000x, what is the apparent diameter of the specimen?

$$2 \ \mu m \times 1000 = 2000 \ \mu m$$

Question 1

Which type of microscopy would be most appropriate for observing the surface details of a virus particle, and why?

Accepted Answer

Scanning electron microscopy (SEM), because it provides high-resolution images of specimen surfaces.

Question 2

A microbiologist wants to observe live, unstained bacteria to study their motility. Which microscopy technique should be used?

Accepted Answer

Darkfield microscopy

Question 3

What is the main advantage of using immersion oil with a 100X objective lens in light microscopy?

Accepted Answer

It reduces light refraction, increasing resolution.

Question 4

Which equation correctly describes the resolving power ($$d) of a $$microscope, where $$\lambda is $$the wavelength of light and $$NA is $$the numerical aperture?

Accepted Answer

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

Question 5

A researcher stains a bacterial sample with a fluorescent dye and observes it under a microscope using a UV light source. Which type of microscopy is being used?

Accepted Answer

Fluorescence microscopy

Question 6

Which of the following is a key difference between transmission electron microscopy (TEM) and scanning electron microscopy (SEM)?

Accepted Answer

TEM provides images of internal structures, while SEM provides images of surfaces.

Question 7

Why is it necessary to use heavy metal stains in transmission electron microscopy (TEM)?

Accepted Answer

To enhance the contrast by scattering electrons.

Question 8

Which microscopy technique would be best for reconstructing a three-dimensional image of a cell's internal structures?

Accepted Answer

Confocal microscopy

Question 9

A student observes a specimen that appears bright against a dark background without staining. Which microscopy technique is being used?

Accepted Answer

Darkfield microscopy

Question 10

Which of the following best explains why electron microscopes have higher resolving power than light microscopes?

Accepted Answer

Electrons have a much shorter wavelength than visible light.

Question 11

A scientist wants to observe the arrangement of proteins within a living cell in real time. Which microscopy technique would be most suitable?

Accepted Answer

Confocal microscopy with fluorescent protein tags

Question 12

Which part of the compound light microscope is responsible for focusing light onto the specimen?

Accepted Answer

Condenser lens

Question 13

If a specimen is 2 μm in diameter and is viewed under a microscope with a total magnification of 1000x, what is the apparent diameter of the specimen?

Accepted Answer

$$2 \ \mu m 	imes 1000 = 2000 \ \mu m$$

Question 14

Which of the following statements about phase-contrast microscopy is correct?

Accepted Answer

It is used to observe live, unstained cells by enhancing differences in refractive index.

Question 15

A sample is prepared for electron microscopy by coating it with gold. Which type of electron microscopy is this preparation most likely for?

Accepted Answer

Scanning electron microscopy (SEM)

Question 16

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

Accepted Answer

It controls the amount of light entering the condenser.

Question 17

Why is it important to use ultra-thin specimens in transmission electron microscopy (TEM)?

Accepted Answer

To allow electrons to pass through the specimen for imaging.

Question 18

Which microscopy technique would be most appropriate for visualizing the arrangement of chromosomes during cell division in three dimensions?

Accepted Answer

Confocal microscopy

Question 19

A microbiologist observes a specimen using a compound light microscope with a 10x ocular lens and a 40x objective lens. What is the total magnification?

Accepted Answer

$$10 	imes 40 = 400$$

Question 20

Which of the following is a limitation of light microscopy compared to electron microscopy?

Accepted Answer

Light microscopy has lower resolving power due to the longer wavelength of visible light.

Microscopy: Observing Microorganisms Through a Microscope

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