Q: Which formula correctly represents the resolving power of a microscope?

$$0.5 \times \frac{\text{wavelength}}{NA}$$

Question 1

Which of the following best describes the primary goal of laboratory containment procedures?

Accepted Answer

To protect personnel and the immediate laboratory environment from exposure to infectious agents.

Question 2

A researcher is working with Bacillus cereus in a teaching lab. Which biosafety level (BSL) is most appropriate for this organism?

Accepted Answer

BSL-1

Question 3

Which of the following organisms would require the highest biosafety level due to its inability to be treated easily and its lethal risk?

Accepted Answer

Lassa virus

Question 4

If the eyepiece of a compound light microscope is 10x and the objective lens is 40x, what is the total magnification?

Accepted Answer

$$10 	imes 40 = 400$$

Question 5

Which formula correctly represents the resolving power of a microscope?

Accepted Answer

$$0.5 	imes \frac{	ext{wavelength}}{NA}$$

Question 6

Why is immersion oil used with the 100x objective lens in light microscopy?

Accepted Answer

To prevent the diffraction of light by matching the refractive index of glass.

Question 7

Which of the following steps will NOT maximize the resolving power of a light microscope?

Accepted Answer

Stopping down the diaphragm too much.

Question 8

A student observes a slide of the letter 'e' under a compound light microscope. How will the image appear?

Accepted Answer

Magnified, upside down and reversed.

Question 9

Which type of microscope is best for observing living, unstained cells and why?

Accepted Answer

Phase contrast microscope, because it enhances contrast without killing cells.

Question 10

What happens to the working distance as magnification increases in a compound light microscope?

Accepted Answer

It decreases.

Question 11

A microbiologist wants to observe two points that are very close together. Which factor should be maximized to improve resolution?

Accepted Answer

Numerical aperture (NA)

Question 12

Which of the following best describes 'depth of field' in microscopy?

Accepted Answer

The range of depth that a specimen is in acceptable focus.

Question 13

Which biosafety level is appropriate for handling Yersinia pestis, considering its ability to cause disease and spread?

Accepted Answer

BSL-3

Question 14

A laboratory is working with a virus that poses a lethal risk and does not respond to vaccines or antimicrobial therapy. Which biosafety level is required?

Accepted Answer

BSL-4

Question 15

Which of the following is a secondary containment measure in a microbiology laboratory?

Accepted Answer

Protecting the environment external to the laboratory from exposure to infectious materials.

Question 16

If the wavelength of light used is $$0.5 \mu m$$ and the numerical aperture (NA) is $$1.25$$, what is the resolving power (distance between two points) of the microscope?

Accepted Answer

$$0.5 \div 1.25 = 0.4 \mu m$$

Question 17

Which of the following statements about refraction and numerical aperture (NA) is correct?

Accepted Answer

Refraction of light decreases NA, diminishing resolving power.

Question 18

Which refractive index is closest to that of immersion oil, and why is this important in microscopy?

Accepted Answer

Glass ($$n = 1.52$$), because it matches the refractive index of the lens and slide.

Question 19

A student is using a compound light microscope and wants to maximize resolution. Which combination of settings should they use?

Accepted Answer

Use a blue filter, raise the condenser, and open the diaphragm.

Basic Microscopy and Laboratory Safety: Microbiology Study Notes

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