Question 1

Which of the following statements best explains why Archaea are classified separately from Bacteria?

Accepted Answer

Archaea have unique membrane lipids and lack peptidoglycan in their cell walls.

Question 2

A clinical laboratory is trying to identify a bacterial pathogen. They perform a Gram stain and observe purple, spherical cells. Which of the following is the most likely classification for this organism?

Accepted Answer

Gram-positive coccus

Question 3

Which of the following methods would be most appropriate for distinguishing between two closely related bacterial strains that cannot be differentiated by morphology or biochemical tests?

Accepted Answer

DNA-DNA hybridization

Question 4

A patient is suspected of having tuberculosis. Which staining technique would be most useful for confirming the presence of Mycobacterium tuberculosis in a sputum sample?

Accepted Answer

Acid-fast stain

Question 5

Which of the following best describes the principle behind the ELISA test?

Accepted Answer

Antigen-antibody interactions resulting in a color change

Question 6

A bacterium is isolated from a patient and is found to be rod-shaped, Gram-negative, and capable of fermenting lactose. According to the dichotomous key, which genus is most likely?

Accepted Answer

Escherichia

Question 7

Which of the following is a unique feature of the cell membrane lipids in Archaea compared to Bacteria?

Accepted Answer

Archaea have branched carbon chains attached by ether linkages.

Question 8

Which of the following is NOT a method used in the classification of microorganisms?

Accepted Answer

Photosynthetic pigment analysis

Question 9

A scientist uses a DNA microarray to identify a bacterial pathogen. What is the main advantage of this technique?

Accepted Answer

It allows for rapid identification of multiple genes or sequences simultaneously.

Question 10

Which of the following bacteria is correctly matched with its disease and classification?

Accepted Answer

Streptococcus pyogenes – causes strep throat – Gram-positive

Question 11

Which of the following best describes the process of DNA-DNA hybridization for determining evolutionary relationships?

Accepted Answer

Mixing DNA from two organisms, heating to separate strands, cooling to allow hybridization, and measuring the degree of hybridization.

Question 12

Which of the following is a characteristic unique to the Domain Archaea?

Accepted Answer

Ability to live in extreme environments such as high temperature or salinity

Question 13

A rapid identification system for enteric bacteria, such as the EnteroPluri test, is based on which principle?

Accepted Answer

Simultaneous biochemical testing in multiple compartments

Question 14

Which of the following is a medically important genus of Alphaproteobacteria known for nitrogen fixation in legumes?

Accepted Answer

Rhizobium

Question 15

Which of the following best explains why phage typing is useful in epidemiology?

Accepted Answer

It distinguishes bacterial strains based on susceptibility to specific bacteriophages.

Question 16

Which of the following is a correct order of taxonomic hierarchy from broadest to most specific?

Accepted Answer

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species

Question 17

Which of the following is a distinguishing feature of Gram-negative bacteria compared to Gram-positive bacteria?

Accepted Answer

Presence of an outer membrane containing lipopolysaccharides

Question 18

Which of the following is a practical application of fatty acid methyl ester (FAME) analysis in microbiology?

Accepted Answer

Identifying bacteria based on their unique fatty acid profiles

Question 19

Which of the following statements about serology is correct?

Accepted Answer

Serology uses antigen-antibody interactions to identify microorganisms.

Classification of Microorganisms & Prokaryotic Diversity: Study Notes

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