Q: Which equation correctly represents the total magnification of a compound light microscope?

$Total\ Magnification = Objective \times Ocular$

Question 1

Which of the following microorganisms can be visualized using a light microscope (LM) but NOT with the unaided eye?

Accepted Answer

Bacteria

Question 2

A clinical sample is suspected to contain SARS-CoV-2 viral spikes. Which microscopy technique would be most appropriate to visualize these surface features?

Accepted Answer

Scanning electron microscopy (SEM)

Question 3

Which staining technique is most useful for determining the appropriate antibiotic therapy for a bacterial infection?

Accepted Answer

Gram stain

Question 4

A microbiologist wants to observe the internal ultrastructure of mitochondria in a kidney biopsy. Which microscope should be used?

Accepted Answer

Transmission electron microscope (TEM)

Question 5

Which equation correctly represents the total magnification of a compound light microscope?

Accepted Answer

$Total\ Magnification = Objective 	imes Ocular$

Question 6

Why does oil immersion improve resolution in light microscopy?

Accepted Answer

It reduces refraction of light between the specimen and the lens.

Question 7

Which bacterial structure is too thin to be seen with a light microscope unless stained, but is revealed in detail by electron microscopy?

Accepted Answer

Flagella

Question 8

A sample contains both Staphylococcus aureus (Gram+) and Escherichia coli (Gram–). After Gram staining, what colors would you expect to see under the microscope?

Accepted Answer

S. aureus is purple, E. coli is pink

Question 9

Which of the following best explains why viruses cannot be visualized with a light microscope?

Accepted Answer

Viruses are typically smaller than the resolving power of light microscopes

Question 10

A researcher is studying biofilm formation on catheters. Which microscopy method would provide 3D reconstruction of the biofilm?

Accepted Answer

Confocal microscopy

Question 11

Which of the following is a differential stain used to diagnose Mycobacterium tuberculosis?

Accepted Answer

Acid-fast stain

Question 12

Which of the following best describes the arrangement of Streptococcus pyogenes as seen under a light microscope?

Accepted Answer

Chains

Question 13

A student observes twitching motility in a bacterial sample using electron microscopy. Which structure is responsible for this movement?

Accepted Answer

Pili

Question 14

Which of the following statements about prokaryotic cells is TRUE?

Accepted Answer

Their DNA is located in a nucleoid region.

Question 15

Which clinical scenario would most likely require the use of a negative stain?

Accepted Answer

Identifying the presence of a capsule in Streptococcus pneumoniae

Question 16

Which of the following best describes the function of the cytoskeleton in eukaryotic cells?

Accepted Answer

Maintains cell shape and serves as tracks for transporting vesicles

Question 17

A microbiologist is comparing the resolution of two microscopes. Microscope A uses visible light ($\lambda = 500\ nm$), and Microscope B uses electrons ($\lambda = 0.005\ nm$). Which microscope will provide greater resolution and why?

Accepted Answer

Microscope B, because shorter wavelength increases resolution

Question 18

Which of the following is TRUE regarding Gram-negative bacteria?

Accepted Answer

They possess an outer membrane containing lipopolysaccharide (LPS).

Question 19

Which microscopy method is best for observing living organisms and their internal structures without staining?

Accepted Answer

Phase-contrast microscopy

Question 20

A scientist needs to distinguish between Staphylococcus aureus (clusters) and Streptococcus pyogenes (chains) in a clinical sample. Which feature should they focus on under the light microscope?

Accepted Answer

Arrangement of cells

Microscopy and Cell Structure in General Microbiology

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