Question 1

Which of the following best describes the primary purpose of taxonomy in microbiology?

Accepted Answer

To show the degree of similarity among organisms by classifying them into categories

Question 2

Why is 16S rRNA commonly used to determine evolutionary relationships among prokaryotes?

Accepted Answer

Because it is present in all living cells, has a similar function in all cells, and is well conserved

Question 3

Which statement correctly distinguishes prokaryotic species from eukaryotic species according to the taxonomic hierarchy?

Accepted Answer

Prokaryotic species are populations of cells with similar characteristics, while eukaryotic species are groups of closely related organisms that breed among themselves

Question 4

In the three-domain system proposed by Woese, which molecular technique is primarily used to determine phylogenetic relationships?

Accepted Answer

Sequencing of 16S rRNA in prokaryotes and 18S rRNA in eukaryotes

Question 5

A scientist discovers a new microorganism and wants to classify it. Which step should they take first according to standard methods of classification?

Accepted Answer

Place it in a group of related species based on its characteristics

Question 6

Which of the following is NOT a reason why rRNA is used for phylogenetic studies?

Accepted Answer

It is highly variable and changes rapidly

Question 7

Which domain includes organisms that have membrane-bound organelles and can form multicellular structures?

Accepted Answer

Eukarya

Question 8

A phylogenetic tree is constructed using genetic data. What does a branch point (node) on this tree represent?

Accepted Answer

A common ancestor from which descendant species diverged

Question 9

Which of the following best describes a 'strain' in prokaryotic taxonomy?

Accepted Answer

Genetically different cells within a clone

Question 10

If two bacterial cultures are derived from the same parent cell but show genetic differences, what are these called?

Accepted Answer

Strains

Question 11

Which of the following is a real-world application of phylogenetic analysis in microbiology?

Accepted Answer

Determining the evolutionary origin of antibiotic resistance genes in hospital-acquired infections

Question 12

Which equation would you use to calculate the genetic similarity between two organisms based on their rRNA sequences?

Accepted Answer

$$S = \frac{N_{identical}}{N_{total}}$$

Question 13

Which of the following statements about the three-domain system is correct?

Accepted Answer

Bacteria and Archaea are both prokaryotes

Question 14

A researcher is using phenotypic relationships to classify microorganisms. Which property is most likely being used?

Accepted Answer

Observable characteristics such as cell shape and metabolic activity

Question 15

Which process is described as matching the characteristics of an unknown organism to lists of known organisms?

Accepted Answer

Identification

Question 16

Which of the following is a direct result of mutations accumulated in genomes over time?

Accepted Answer

Record of evolutionary relationships used to construct phylogenetic trees

Question 17

Which of the following best explains why the All Species Inventory (2001–2025) is significant in microbiology?

Accepted Answer

It aims to identify all species of life on Earth, providing a comprehensive database for classification and evolutionary studies

Question 18

Which of the following is NOT a subdivision in the taxonomic hierarchy developed by Linnaeus?

Accepted Answer

Metabolic pathway

Question 19

A culture of bacteria grown in laboratory media is best described as:

Accepted Answer

A culture

Question 20

Which of the following kingdoms is NOT included in the domain Eukarya?

Accepted Answer

Bacteria

Microbial Classification and Phylogeny: Taxonomy, Domains, and Identification

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