Question 1

A bacterial cell measures 10 µm in length. How long is this cell in nanometers ($$nm$$)?

Accepted Answer

$$10,000 nm$$

Question 2

Which of the following best describes the term 'resolution' in microscopy?

Accepted Answer

The ability to distinguish two points as separate objects

Question 3

Why do electron microscopes have greater resolution than light microscopes?

Accepted Answer

Electrons have much shorter wavelengths than visible light

Question 4

A compound light microscope has an ocular lens of $$10	imes$$ and an objective lens of $$40	imes. $$What is the total magnification?

Accepted Answer

$$400	imes$$

Question 5

Which microscope would be most appropriate to view the surface details of a virus particle?

Accepted Answer

Scanning Electron Microscope (SEM)

Question 6

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

Accepted Answer

It increases the refractive index, allowing more light to enter the lens

Question 7

Which staining technique would you use to identify Mycobacterium tuberculosis in a clinical sample?

Accepted Answer

Acid-fast stain

Question 8

After performing a Gram stain, what color will Gram-negative bacteria appear under the microscope?

Accepted Answer

Red or pink

Question 9

Which of the following best explains why a negative stain does not color the cell?

Accepted Answer

The negatively charged dye is repelled by the negatively charged cell surface

Question 10

Which of the following is a key difference between brightfield and darkfield microscopy?

Accepted Answer

Brightfield shows dark objects on a bright background; darkfield shows bright objects on a dark background

Question 11

Which of the following best describes the purpose of a mordant in staining procedures?

Accepted Answer

To enhance the binding of the stain to the cell or structure

Question 12

A student observes a specimen using a light microscope with a resolution of $$0.2\ \mu m. $$What does this mean?

Accepted Answer

Two points at least $$0.2\ \mu m$$ apart can be distinguished as separate

Question 13

Which of the following stains is used to visualize bacterial capsules?

Accepted Answer

Negative stain

Question 14

Which of the following is a correct sequence for the Gram stain procedure?

Accepted Answer

Crystal violet, iodine, alcohol, safranin

Question 15

Which of the following best explains why the Gram stain is so useful in microbiology?

Accepted Answer

It differentiates bacteria based on cell wall structure

Question 16

Which of the following statements about electron microscopy is TRUE?

Accepted Answer

TEM provides detailed images of internal cell structures, while SEM provides 3D images of surfaces

Question 17

Which of the following is a reason why too much light can reduce contrast in a light microscope?

Accepted Answer

Excess light washes out differences between specimen and background

Question 18

Which two genera of bacteria are known for forming endospores, which can be visualized using the endospore stain?

Accepted Answer

Bacillus and Clostridium

Question 19

A clinical lab is tasked with identifying Treponema pallidum in a patient sample. Which microscopy technique and stain would be most appropriate?

Accepted Answer

Darkfield microscopy with immunofluorescence

Question 20

Which of the following best describes the relationship between wavelength ($$\lambda) $$and resolution in microscopy?

Accepted Answer

Shorter $$\lambda$$ results in better resolution

Observing Microorganisms Through a Microscope: Principles, Techniques, and Applications

Study Guide - Practice Questions