Q: Which of the following is the correct conversion from 2 millimeters (mm) to micrometers ($$ \mu m $$)? $$1 \text{ mm} = 1000 \ \mu m$$

$$2 \text{ mm} = 2000 \ \mu m$$

Question 1

Which of the following is the correct conversion from 2 millimeters (mm) to micrometers ($$ \mu m $$)?

$$1 	ext{ mm} = 1000 \ \mu m$$

Accepted Answer

$$2 	ext{ mm} = 2000 \ \mu m$$

Question 2

If a microscope has an objective lens with a magnification of $$40	imes$$ and an ocular lens with a magnification of $$10	imes$$, what is the total magnification?

$$	ext{Total Magnification} = 	ext{Objective Magnification} 	imes 	ext{Ocular Magnification}$$

Accepted Answer

$$400	imes$$

Question 3

Which factor does NOT directly affect the resolving power of a light microscope?

$$	ext{Resolving Power} = \frac{0.61 \lambda}{n \sin 	heta}$$

Accepted Answer

Magnification of the ocular lens

Question 4

Which of the following best describes the main difference between scanning electron microscopy (SEM) and transmission electron microscopy (TEM)?

Accepted Answer

SEM provides 3D surface images, while TEM provides detailed internal structures.

Question 5

A student is using a light microscope and wants to increase the resolving power. Which adjustment would be most effective?

$$	ext{Resolving Power} = \frac{0.61 \lambda}{n \sin 	heta}$$

Accepted Answer

Use a shorter wavelength of light

Question 6

Which staining technique is most appropriate for differentiating between Gram-positive and Gram-negative bacteria?

Accepted Answer

Gram stain

Question 7

During Gram staining, what is the primary reason Gram-positive bacteria retain the crystal violet stain?

$$	ext{Thick peptidoglycan layer in cell wall}$$

Accepted Answer

They have a thick peptidoglycan layer that traps the stain.

Question 8

Which of the following best explains why acid-fast staining is used in clinical microbiology?

Accepted Answer

To identify bacteria with waxy cell walls, such as Mycobacterium species

Question 9

A clinical sample is stained and observed to have red cells after acid-fast staining. What is the most likely identity of these cells?

Accepted Answer

Mycobacterium tuberculosis

Question 10

Which of the following is NOT a purpose of using a negative stain in microbiology?

Accepted Answer

To differentiate between Gram-positive and Gram-negative bacteria

Question 11

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

Accepted Answer

Crystal violet, iodine, alcohol, safranin

Question 12

Which of the following best describes binomial nomenclature?

Accepted Answer

A two-part scientific naming system using genus and species

Question 13

Which of the following is NOT one of the five major ways microorganisms can be classified?

Accepted Answer

By their Gram stain reaction

Question 14

A dichotomous key is most useful for which of the following tasks?

Accepted Answer

Identifying unknown microorganisms based on observable traits

Question 15

Which of the following statements about scientific naming is FALSE?

Accepted Answer

The species name is always capitalized.

Question 16

A microbiologist is using a dichotomous key to identify a bacterial isolate. The first step asks if the organism is Gram-positive or Gram-negative. What is the next logical step if the organism is Gram-negative?

Accepted Answer

Test for lactose fermentation

Question 17

Which of the following best explains why oil immersion is used with the 100x objective lens in light microscopy?

$$	ext{Oil increases the numerical aperture by reducing light refraction}$$

Accepted Answer

Oil increases the numerical aperture by reducing light refraction.

Question 18

Which of the following is a correct application of the acid-fast stain in a clinical setting?

Accepted Answer

Diagnosing tuberculosis in a sputum sample

Question 19

A scientist is comparing two microscopes: one with a numerical aperture (NA) of 1.25 and another with an NA of 0.65. If both use light of wavelength $$500 	ext{ nm}$$, which microscope has the better resolving power?

$$	ext{Resolving Power} = \frac{0.61 \lambda}{n \sin 	heta}$$

Accepted Answer

The microscope with NA 1.25

Question 20

Which of the following is a key difference between simple and differential staining techniques?

Accepted Answer

Simple staining uses one dye, while differential staining uses multiple dyes to distinguish cell types.

Microscopy, Staining, and Classification: Study Guide Notes (Chapter 4)

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