Q: In a compound light microscope, what is the formula for total magnification?

Total magnification $$= \text{objective lens} \times \text{ocular lens}$$

Question 1

Which of the following best describes the difference between classification and identification of microorganisms?

Accepted Answer

Classification involves placing organisms in groups of related species, while identification involves matching characteristics of an unknown organism to lists of known organisms.

Question 2

A prokaryotic species is defined as:

Accepted Answer

A population of cells with similar characteristics.

Question 3

Which method would be most appropriate for identifying bacteria that lack cell walls?

Accepted Answer

Biochemical tests to determine enzyme presence.

Question 4

In a compound light microscope, what is the formula for total magnification?

Accepted Answer

Total magnification $$= 	ext{objective lens} 	imes 	ext{ocular lens}$$

Question 5

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

Accepted Answer

To prevent light from refracting and being lost, thus increasing resolution.

Question 6

Which of the following is NOT a type of light microscopy?

Accepted Answer

Transmission electron microscopy.

Question 7

A basic dye stains cells because:

Accepted Answer

The chromophore is a cation that binds to negatively charged cell components.

Question 8

Which staining technique would you use to differentiate between gram-positive and gram-negative bacteria?

Accepted Answer

Gram stain.

Question 9

What is the primary purpose of fixing a smear before staining?

Accepted Answer

To attach and kill the microorganisms, preserving their structure.

Question 10

Which of the following is a real-world application of the ELISA test?

Accepted Answer

Detecting specific bacterial antigens in a patient sample.

Question 11

A slide agglutination test is used to:

Accepted Answer

Differentiate between species and strains within species using antibodies.

Question 12

Which of the following statements about viral species is correct?

Accepted Answer

Viral species are not part of any domain and require a host cell for replication.

Question 13

Which technique is most useful for classifying a newly discovered microbe based on its genetic material?

Accepted Answer

DNA sequencing.

Question 14

What is the resolving power of a microscope that can distinguish between two points at least 0.4 nm apart?

Accepted Answer

0.4 nm.

Question 15

Which of the following is a chemoheterotrophic organism with chitin cell walls?

Accepted Answer

Fungi.

Question 16

A negative stain colors the background instead of the cell because:

Accepted Answer

The cell repels the acidic dye due to its negative charge.

Question 17

Which of the following is a multi-step identification method that uses a tube containing media for 15 biochemical tests?

Accepted Answer

EnteroPluri Test.

Question 18

Which of the following is true about the refractive index in microscopy?

Accepted Answer

It is a measure of the light-bending ability of a medium.

Question 19

Which of the following is a real-world scenario where ribotyping would be used?

Accepted Answer

Identifying bacterial species in a patient’s microbiome based on rRNA sequences.

Question 20

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

Accepted Answer

Total magnification $$= 40 	imes 10 = 400$$

Classification and Identification of Microorganisms & Microscopy in Microbiology

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