Microbiology Quiz: Taxonomy And Binomial Nomenclature
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Taxonomy And Binomial NomenclatureQuestion 1 of 20

The modern three-domain system of classification, proposed by Carl Woese, is primarily based on which type of evidence that revealed a fundamental division among living organisms?

Differences in cell wall composition, specifically the presence or absence of peptidoglycan.
Metabolic diversity, such as the ability to perform photosynthesis or chemosynthesis.
Comparative morphology observed through electron microscopy.
Analysis of conserved ribosomal RNA (rRNA) gene sequences.
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Microbiology Quiz

Microbiology Quiz: Taxonomy And Binomial Nomenclature

Practice Taxonomy And Binomial Nomenclature in Microbiology with focused quiz questions that help you check what you know, review explanations, and build confidence with test-style prompts.

What this quiz covers

This quiz focuses on Taxonomy And Binomial Nomenclature, giving you a quick way to practice the rules, question types, and explanations that matter most for Microbiology.

How to use this quiz

Try each quiz question before looking at the correct answer. Use the explanations to review missed ideas, then come back to similar questions until the pattern feels familiar.

All questions

Question 1

The modern three-domain system of classification, proposed by Carl Woese, is primarily based on which type of evidence that revealed a fundamental division among living organisms?

  1. Differences in cell wall composition, specifically the presence or absence of peptidoglycan.
  2. Metabolic diversity, such as the ability to perform photosynthesis or chemosynthesis.
  3. Comparative morphology observed through electron microscopy.
  4. Analysis of conserved ribosomal RNA (rRNA) gene sequences. (correct answer)
Explanation: When you encounter questions about classification systems in microbiology, focus on the foundational evidence that revolutionized our understanding of evolutionary relationships. Carl Woese's three-domain system represents one of the most significant advances in biological classification. The correct answer is D because Woese's groundbreaking work was based specifically on comparing ribosomal RNA (rRNA) gene sequences, particularly the 16S rRNA gene. These sequences are highly conserved across all life forms but contain enough variation to reveal evolutionary relationships. When Woese analyzed these sequences in the 1970s, he discovered that what were previously called "archaebacteria" were as genetically distinct from true bacteria as both groups were from eukaryotes. This molecular evidence revealed three fundamental domains: Bacteria, Archaea, and Eukarya. Option A is incorrect because cell wall differences, while important for bacterial classification, don't provide the broad evolutionary perspective needed for domain-level classification. Many archaea lack peptidoglycan but have other cell wall components. Option B is wrong because metabolic diversity exists within domains rather than defining them—you can find similar metabolic processes across different domains. Option C is incorrect because morphological similarities can be misleading due to convergent evolution, and electron microscopy alone cannot reveal the deep evolutionary relationships that molecular analysis provides. Remember that modern classification increasingly relies on molecular evidence rather than observable characteristics. When studying microbial classification, prioritize understanding how genetic analysis, especially rRNA sequencing, has reshaped our view of life's diversity and evolutionary history.

Question 2

A microbiologist is working to name, group, and determine the identity of a newly isolated bacterium. The microbiologist performs the following tasks:

  1. Conducts a series of biochemical tests to determine the organism's metabolic characteristics, comparing them to known species.

  2. Arranges the new isolate into a hierarchical system with other known bacteria based on shared evolutionary ancestry.

  3. Assigns the name Pseudomonas aqua to the new isolate according to the rules of the International Code of Nomenclature of Prokaryotes.

Which task corresponds to the practice of classification?

  1. Task 1
  2. Task 2 (correct answer)
  3. Task 3
  4. Tasks 1 and 3
Explanation: This question distinguishes between three key activities in taxonomy. Task 1 (using tests to determine what an organism is) is identification. Task 3 (assigning a formal name) is nomenclature. Task 2 (arranging organisms into groups based on relationships) is the definition of classification. Therefore, Task 2 is the correct answer.

Question 3

The full scientific name of the bacterium that causes Lyme disease is cited as Borrelia burgdorferi Johnson et al., 1984. What information does the 'Johnson et al., 1984' part of the name provide?

  1. It indicates the geographic location where the species was first isolated.
  2. It names the patient from whom the first strain was cultured and the year.
  3. It identifies the author(s) who first published a valid description of the species and the year of publication. (correct answer)
  4. It specifies the type strain designated for this species and the year it was deposited in a culture collection.
Explanation: In formal taxonomic nomenclature, the name(s) and year that follow the binomial name constitute the authority citation. This citation credits the author(s) who first validly published the name and description of that species and specifies the year of that publication. It is not related to geographic location, patient names, or the type strain designation details.

Question 4

What is the primary role of a 'type strain' in bacterial taxonomy?

  1. It is the most medically significant or pathogenic strain of a species.
  2. It represents the most common or abundant strain of a species found in nature.
  3. It is the strain that is commercially used to produce antibiotics or other industrial products.
  4. It serves as the permanent name-bearing reference specimen for a particular species. (correct answer)
Explanation: When you encounter questions about bacterial taxonomy, remember that this field requires standardized reference points to maintain consistency across laboratories and research worldwide. Just like museums need type specimens for species identification, microbiology needs reference strains. A type strain serves as the permanent name-bearing reference specimen for a bacterial species. It's the official "gold standard" that researchers use when comparing newly isolated bacteria to determine if they belong to an existing species or represent something entirely new. These strains are deposited in internationally recognized culture collections and must be used in any formal taxonomic descriptions or revisions. When scientists publish a new species, they must designate a type strain that other researchers can access and study. Option A is incorrect because type strains aren't selected based on pathogenicity or medical importance. Many type strains are actually non-pathogenic laboratory strains. Option B misses the mark because type strains aren't chosen for being common in nature – they're selected for their availability, stability in culture, and ability to represent the species' characteristics. Option C confuses type strains with industrial production strains, which are selected specifically for manufacturing purposes and may be highly modified versions that wouldn't serve as good taxonomic references. For microbiology exams, remember that "type" in bacterial taxonomy always relates to nomenclature and classification standards, not clinical significance or natural abundance. Focus on the concept of reference standards when you see questions about type strains, type species, or taxonomic hierarchy.

Question 5

DNA-DNA hybridization is performed on two bacterial isolates, Strain A and Strain B. The results show 65% hybridization between their genomes. Based on current taxonomic standards for prokaryotes, what is the most appropriate conclusion?

  1. Strain A and Strain B are different strains of the same species.
  2. Strain A and Strain B belong to different families.
  3. Strain A and Strain B are identical strains and belong to the same species.
  4. Strain A and Strain B are different species but belong to the same genus. (correct answer)
Explanation: DNA-DNA hybridization is a fundamental technique in bacterial taxonomy that measures genetic relatedness by determining how much complementary DNA from two organisms will bind together under controlled conditions. The percentage of hybridization directly correlates with evolutionary distance and taxonomic classification. In prokaryotic taxonomy, specific hybridization thresholds define taxonomic boundaries. Strains showing ≥70% DNA-DNA hybridization are considered the same species, while those showing <70% hybridization represent different species. The 65% hybridization between Strain A and Strain B falls below this critical species threshold, indicating they are different species. However, since they still share substantial genetic similarity (65% is relatively high), they likely diverged recently and belong to the same genus. Choice A is incorrect because 65% hybridization falls below the 70% threshold required for same-species classification. Choice C is wrong on multiple levels—65% hybridization indicates neither identical strains nor the same species; identical strains would show nearly 100% hybridization. Choice B incorrectly suggests these organisms belong to different families, which would require much lower hybridization values (typically <30-40%). Choice D correctly identifies that 65% hybridization indicates different species (below 70%) within the same genus (above the much lower family-level threshold). Study tip: Remember the 70% rule for prokaryotic species designation in DNA-DNA hybridization. Below 70% = different species; above 70% = same species. This is a standard benchmark you'll encounter repeatedly in microbiology taxonomy questions.

Question 6

A microbiologist isolates a new organism from a hydrothermal vent. Analysis reveals it lacks a nucleus, has a cell wall with no peptidoglycan, and possesses unique ether-linked membrane lipids. 16S rRNA sequencing shows it is substantially different from all known bacteria. To which domain should this organism be assigned?

  1. Archaea, because of its unique cell wall and membrane composition. (correct answer)
  2. Bacteria, because it is a prokaryote.
  3. Eukarya, because it was found in an extreme environment.
  4. Plantae, because it lacks a nucleus and has a cell wall.
Explanation: When you encounter questions about classifying newly discovered microorganisms, focus on the key distinguishing characteristics that separate the three domains of life: Bacteria, Archaea, and Eukarya. This organism exhibits the classic hallmarks of Archaea. The combination of lacking a nucleus (prokaryotic), having no peptidoglycan in its cell wall, and possessing unique ether-linked membrane lipids are defining features of the archaeal domain. The 16S rRNA sequencing data showing substantial differences from bacteria further confirms this classification, as Archaea have distinct ribosomal RNA sequences that separate them from Bacteria despite both being prokaryotic. Choice A correctly identifies these diagnostic features. Choice B falls into the common misconception that all prokaryotes are bacteria—this ignores the fundamental discovery that prokaryotes actually comprise two distinct domains (Bacteria and Archaea) with very different biochemistry. Choice C incorrectly assumes that extreme environments indicate eukaryotic organisms, when in fact Archaea are the masters of extreme environments like hydrothermal vents. Choice D makes no biological sense, as Plantae is a kingdom within Eukarya, not a domain, and plants are eukaryotic with nuclei. Remember that domain classification relies on molecular and biochemical evidence, not just cellular structure. When you see questions about organism classification, look for these key archaeal markers: ether-linked lipids, absence of peptidoglycan, and distinctive rRNA sequences. These molecular signatures trump simple prokaryotic vs. eukaryotic distinctions.

Question 7

A researcher determines the G+C content of two different bacterial genomes. Genome 1 has a G+C content of 35%, while Genome 2 has a G+C content of 65%. What is the most definitive conclusion that can be drawn from this data alone?

  1. The two bacteria belong to the same species but are different strains.
  2. The two bacteria are not closely related. (correct answer)
  3. The two bacteria are members of the same genus.
  4. One bacterium is a pathogen and the other is not.
Explanation: The percentage of guanine plus cytosine (G+C content) in a genome is a stable characteristic of a species. Organisms that are closely related typically have similar G+C content (usually within a few percent). A large difference, such as 30% in this case, is strong evidence that the organisms are not closely related and do not belong to the same species or likely even the same genus. However, similar G+C content does not guarantee a close relationship, as different organisms can coincidentally have similar values. Therefore, the only strong conclusion is that they are not closely related.

Question 8

A researcher states that coli is the species of the bacterium Escherichia coli. Why is this statement taxonomically incorrect?

  1. The term coli is the genus, and Escherichia is the specific epithet.
  2. Species designations in prokaryotes are based on serotype, such as O157:H7, not names.
  3. The term coli is a subspecies designation, not a species.
  4. The species is designated by the full binomial name, Escherichia coli. (correct answer)
Explanation: Understanding bacterial taxonomy requires mastering the binomial nomenclature system, where organisms are identified by a two-part scientific name consisting of genus and species working together as a unit. The researcher's statement misunderstands how species are defined in taxonomy. In binomial nomenclature, the species is never represented by just the second part of the name alone. The species of Escherichia coli is designated by the complete binomial name "Escherichia coli" - both words together form the species designation. You cannot separate "coli" and call it "the species" any more than you could say "Smith" is someone's complete name when their full name is "John Smith." Looking at why the other options are incorrect: Option A reverses the correct taxonomy - Escherichia is actually the genus (like a surname), while coli is the specific epithet (like a first name). Option B confuses serotyping with species designation. While serotypes like O157:H7 are important for identifying strains within a species, they don't replace the binomial species name system used for all organisms. Option C incorrectly suggests coli represents a subspecies, but subspecies require a third name added after the binomial (like Escherichia coli subsp. something). Remember this key principle: in binomial nomenclature, the species is always the complete two-part name, never just the specific epithet alone. When you see taxonomy questions, always consider both parts of the binomial name as an inseparable unit that together identifies the species.

Question 9

The International Code of Nomenclature of Prokaryotes (ICNP) governs the naming of bacteria and archaea. A scientist proposes the name Inflammatus ruber for a new red-pigmented bacterium that causes inflammation. However, the name is rejected. Which of the following is a plausible reason for rejection based on the ICNP?

  1. The name is a tautonym, where the genus and specific epithet are identical.
  2. The name was not derived from Latin or Greek, as required by the code.
  3. The description was not published in the International Journal of Systematic and Evolutionary Microbiology. (correct answer)
  4. The name describes a characteristic of the disease caused by the organism, which is forbidden.
Explanation: For a new prokaryotic name to be validly published, its description must be published in the International Journal of Systematic and Evolutionary Microbiology (IJSEM), or a description published elsewhere must be announced in the IJSEM. This is a strict rule of the ICNP. The name is not a tautonym (A). The names Inflammatus (from 'inflammation') and ruber ('red') are Latin, so (B) is incorrect. Names can describe diseases, locations, people, or characteristics, so (D) is incorrect.

Question 10

The original name for Escherichia coli was Bacterium coli. A formal citation for the organism is Escherichia coli (Migula, 1895) Castellani and Chalmers, 1919. What is the significance of the parentheses around 'Migula, 1895'?

  1. The species was transferred to a different genus than the one in which it was originally described. (correct answer)
  2. Migula's original description was found to be incomplete and was later amended.
  3. Castellani and Chalmers disputed Migula's findings and proposed an alternative classification.
  4. The name Bacterium coli was deemed illegitimate, requiring a new author citation.
Explanation: When you encounter formal taxonomic citations in microbiology, you're looking at the scientific "paper trail" of how an organism has been classified over time. The format tells you exactly who described the species and when, plus any changes that occurred later. The parentheses around "Migula, 1895" indicate that Migula was the original author who first described this species, but the organism has since been moved to a different genus than where he originally placed it. Migula described it as Bacterium coli in 1895, but Castellani and Chalmers later transferred it to the genus Escherichia in 1919. This is why their names appear outside the parentheses - they made the taxonomic transfer that gave us the current name Escherichia coli. Answer A correctly identifies this genus transfer. Answer B is incorrect because parentheses don't indicate incomplete descriptions - they specifically signal taxonomic transfers. Answer C misinterprets the citation format; the authors aren't disputing findings but following proper nomenclature rules when making taxonomic changes. Answer D is wrong because illegitimate names would be handled differently in formal nomenclature, not through parenthetical citations. The key study tip: In bacterial nomenclature, parentheses around the original author's name and date always mean the species was moved from its original genus to a new one. This is extremely common in microbiology as our understanding of bacterial relationships evolves through molecular techniques.

Question 11

DNA-DNA hybridization is performed on two bacterial isolates, Strain A and Strain B. The results show 65% hybridization between their genomes. Based on current taxonomic standards for prokaryotes, what is the most appropriate conclusion?

  1. Strain A and Strain B are different strains of the same species.
  2. Strain A and Strain B belong to different families.
  3. Strain A and Strain B are identical strains and belong to the same species.
  4. Strain A and Strain B are different species but belong to the same genus. (correct answer)
Explanation: DNA-DNA hybridization is a fundamental technique in bacterial taxonomy that measures genetic relatedness by determining how much complementary DNA from two organisms will bind together under controlled conditions. The percentage of hybridization directly correlates with evolutionary distance and taxonomic classification. In prokaryotic taxonomy, specific hybridization thresholds define taxonomic boundaries. Strains showing ≥70% DNA-DNA hybridization are considered the same species, while those showing <70% hybridization represent different species. The 65% hybridization between Strain A and Strain B falls below this critical species threshold, indicating they are different species. However, since they still share substantial genetic similarity (65% is relatively high), they likely diverged recently and belong to the same genus. Choice A is incorrect because 65% hybridization falls below the 70% threshold required for same-species classification. Choice C is wrong on multiple levels—65% hybridization indicates neither identical strains nor the same species; identical strains would show nearly 100% hybridization. Choice B incorrectly suggests these organisms belong to different families, which would require much lower hybridization values (typically <30-40%). Choice D correctly identifies that 65% hybridization indicates different species (below 70%) within the same genus (above the much lower family-level threshold). Study tip: Remember the 70% rule for prokaryotic species designation in DNA-DNA hybridization. Below 70% = different species; above 70% = same species. This is a standard benchmark you'll encounter repeatedly in microbiology taxonomy questions.

Question 12

A researcher determines the G+C content of two different bacterial genomes. Genome 1 has a G+C content of 35%, while Genome 2 has a G+C content of 65%. What is the most definitive conclusion that can be drawn from this data alone?

  1. The two bacteria belong to the same species but are different strains.
  2. The two bacteria are not closely related. (correct answer)
  3. The two bacteria are members of the same genus.
  4. One bacterium is a pathogen and the other is not.
Explanation: The percentage of guanine plus cytosine (G+C content) in a genome is a stable characteristic of a species. Organisms that are closely related typically have similar G+C content (usually within a few percent). A large difference, such as 30% in this case, is strong evidence that the organisms are not closely related and do not belong to the same species or likely even the same genus. However, similar G+C content does not guarantee a close relationship, as different organisms can coincidentally have similar values. Therefore, the only strong conclusion is that they are not closely related.

Question 13

A researcher isolates a bacterium and its 16S rRNA gene sequence shows 99.5% similarity to the type strain of Bacillus subtilis. However, DNA-DNA hybridization between the isolate and the type strain shows only 55% similarity. How should this isolate be classified?

  1. As a new strain of Bacillus subtilis.
  2. As a new species within the genus Bacillus. (correct answer)
  3. As a member of a new genus closely related to Bacillus.
  4. As a member of Bacillus subtilis, because 16S rRNA similarity is the definitive test.
Explanation: This scenario presents conflicting data that tests understanding of taxonomic standards. While 16S rRNA sequence similarity is excellent for determining genus-level and higher relationships (>97% often suggests same species), the gold standard for species delineation is DNA-DNA hybridization (DDH) or Average Nucleotide Identity (ANI). The DDH value of 55% is well below the 70% threshold required to classify the isolate in the same species. Therefore, despite the high 16S rRNA similarity, it must be classified as a separate species within the same genus, Bacillus.

Question 14

A microbiologist isolates a new organism from a hydrothermal vent. Analysis reveals it lacks a nucleus, has a cell wall with no peptidoglycan, and possesses unique ether-linked membrane lipids. 16S rRNA sequencing shows it is substantially different from all known bacteria. To which domain should this organism be assigned?

  1. Archaea, because of its unique cell wall and membrane composition. (correct answer)
  2. Bacteria, because it is a prokaryote.
  3. Eukarya, because it was found in an extreme environment.
  4. Plantae, because it lacks a nucleus and has a cell wall.
Explanation: When you encounter questions about classifying newly discovered microorganisms, focus on the key distinguishing characteristics that separate the three domains of life: Bacteria, Archaea, and Eukarya. This organism exhibits the classic hallmarks of Archaea. The combination of lacking a nucleus (prokaryotic), having no peptidoglycan in its cell wall, and possessing unique ether-linked membrane lipids are defining features of the archaeal domain. The 16S rRNA sequencing data showing substantial differences from bacteria further confirms this classification, as Archaea have distinct ribosomal RNA sequences that separate them from Bacteria despite both being prokaryotic. Choice A correctly identifies these diagnostic features. Choice B falls into the common misconception that all prokaryotes are bacteria—this ignores the fundamental discovery that prokaryotes actually comprise two distinct domains (Bacteria and Archaea) with very different biochemistry. Choice C incorrectly assumes that extreme environments indicate eukaryotic organisms, when in fact Archaea are the masters of extreme environments like hydrothermal vents. Choice D makes no biological sense, as Plantae is a kingdom within Eukarya, not a domain, and plants are eukaryotic with nuclei. Remember that domain classification relies on molecular and biochemical evidence, not just cellular structure. When you see questions about organism classification, look for these key archaeal markers: ether-linked lipids, absence of peptidoglycan, and distinctive rRNA sequences. These molecular signatures trump simple prokaryotic vs. eukaryotic distinctions.

Question 15

A microbiologist is working to name, group, and determine the identity of a newly isolated bacterium. The microbiologist performs the following tasks:

  1. Conducts a series of biochemical tests to determine the organism's metabolic characteristics, comparing them to known species.

  2. Arranges the new isolate into a hierarchical system with other known bacteria based on shared evolutionary ancestry.

  3. Assigns the name Pseudomonas aqua to the new isolate according to the rules of the International Code of Nomenclature of Prokaryotes.

Which task corresponds to the practice of classification?

  1. Task 1
  2. Task 2 (correct answer)
  3. Task 3
  4. Tasks 1 and 3
Explanation: This question distinguishes between three key activities in taxonomy. Task 1 (using tests to determine what an organism is) is identification. Task 3 (assigning a formal name) is nomenclature. Task 2 (arranging organisms into groups based on relationships) is the definition of classification. Therefore, Task 2 is the correct answer.

Question 16

The original name for Escherichia coli was Bacterium coli. A formal citation for the organism is Escherichia coli (Migula, 1895) Castellani and Chalmers, 1919. What is the significance of the parentheses around 'Migula, 1895'?

  1. The species was transferred to a different genus than the one in which it was originally described. (correct answer)
  2. Migula's original description was found to be incomplete and was later amended.
  3. Castellani and Chalmers disputed Migula's findings and proposed an alternative classification.
  4. The name Bacterium coli was deemed illegitimate, requiring a new author citation.
Explanation: When you encounter formal taxonomic citations in microbiology, you're looking at the scientific "paper trail" of how an organism has been classified over time. The format tells you exactly who described the species and when, plus any changes that occurred later. The parentheses around "Migula, 1895" indicate that Migula was the original author who first described this species, but the organism has since been moved to a different genus than where he originally placed it. Migula described it as Bacterium coli in 1895, but Castellani and Chalmers later transferred it to the genus Escherichia in 1919. This is why their names appear outside the parentheses - they made the taxonomic transfer that gave us the current name Escherichia coli. Answer A correctly identifies this genus transfer. Answer B is incorrect because parentheses don't indicate incomplete descriptions - they specifically signal taxonomic transfers. Answer C misinterprets the citation format; the authors aren't disputing findings but following proper nomenclature rules when making taxonomic changes. Answer D is wrong because illegitimate names would be handled differently in formal nomenclature, not through parenthetical citations. The key study tip: In bacterial nomenclature, parentheses around the original author's name and date always mean the species was moved from its original genus to a new one. This is extremely common in microbiology as our understanding of bacterial relationships evolves through molecular techniques.

Question 17

The International Code of Nomenclature of Prokaryotes (ICNP) governs the naming of bacteria and archaea. A scientist proposes the name Inflammatus ruber for a new red-pigmented bacterium that causes inflammation. However, the name is rejected. Which of the following is a plausible reason for rejection based on the ICNP?

  1. The name is a tautonym, where the genus and specific epithet are identical.
  2. The name was not derived from Latin or Greek, as required by the code.
  3. The description was not published in the International Journal of Systematic and Evolutionary Microbiology. (correct answer)
  4. The name describes a characteristic of the disease caused by the organism, which is forbidden.
Explanation: For a new prokaryotic name to be validly published, its description must be published in the International Journal of Systematic and Evolutionary Microbiology (IJSEM), or a description published elsewhere must be announced in the IJSEM. This is a strict rule of the ICNP. The name is not a tautonym (A). The names Inflammatus (from 'inflammation') and ruber ('red') are Latin, so (B) is incorrect. Names can describe diseases, locations, people, or characteristics, so (D) is incorrect.

Question 18

A researcher isolates a bacterium and its 16S rRNA gene sequence shows 99.5% similarity to the type strain of Bacillus subtilis. However, DNA-DNA hybridization between the isolate and the type strain shows only 55% similarity. How should this isolate be classified?

  1. As a new strain of Bacillus subtilis.
  2. As a new species within the genus Bacillus. (correct answer)
  3. As a member of a new genus closely related to Bacillus.
  4. As a member of Bacillus subtilis, because 16S rRNA similarity is the definitive test.
Explanation: This scenario presents conflicting data that tests understanding of taxonomic standards. While 16S rRNA sequence similarity is excellent for determining genus-level and higher relationships (>97% often suggests same species), the gold standard for species delineation is DNA-DNA hybridization (DDH) or Average Nucleotide Identity (ANI). The DDH value of 55% is well below the 70% threshold required to classify the isolate in the same species. Therefore, despite the high 16S rRNA similarity, it must be classified as a separate species within the same genus, Bacillus.

Question 19

Two newly discovered bacteria are found to belong to the same Order. Based on the hierarchical nature of Linnaean taxonomy, which of the following statements must also be true?

  1. They must belong to the same Family.
  2. They must belong to the same Class. (correct answer)
  3. They must belong to the same Genus.
  4. They must be the same Species.
Explanation: The Linnaean hierarchy is nested, meaning that broader categories contain the more specific ones. The hierarchy is Domain > Kingdom > Phylum > Class > Order > Family > Genus > Species. If two organisms are in the same Order, they must also be in the same higher, more inclusive taxa, which are Class, Phylum, Kingdom, and Domain. They do not necessarily have to be in the same lower, more specific taxa like Family, Genus, or Species.

Question 20

The full scientific name of the bacterium that causes Lyme disease is cited as Borrelia burgdorferi Johnson et al., 1984. What information does the 'Johnson et al., 1984' part of the name provide?

  1. It indicates the geographic location where the species was first isolated.
  2. It names the patient from whom the first strain was cultured and the year.
  3. It identifies the author(s) who first published a valid description of the species and the year of publication. (correct answer)
  4. It specifies the type strain designated for this species and the year it was deposited in a culture collection.
Explanation: In formal taxonomic nomenclature, the name(s) and year that follow the binomial name constitute the authority citation. This citation credits the author(s) who first validly published the name and description of that species and specifies the year of that publication. It is not related to geographic location, patient names, or the type strain designation details.