Download Microbiology Problem Drill – 08: Classification of Microorganisms

Microbiology Problem Drill – 08: Classification of Microorganisms
Question No. 1 of 10
Instruction: (1) Read the problem statement and answer choices carefully (2) Work the problems on paper as needed (3)
Pick the answer (4) Go back to review the core concept tutorial as needed.
Question 1. In the binomial system of naming which term is always written in lowercase?
(A) Kingdom
(B) Domain
(C) Genus
(D) Specific epithet
Question
A. Incorrect!
In the binomial naming convention the “Kingdom” is not part of the name.
B. Incorrect!
In the binomial naming convention the “Domain” is not part of the name.
C. Incorrect!
In the binomial naming convention genus is the first part of the name.
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D. Correct!
Yes the second word in the binomial naming system is referred to as the specific epithet.
This question is a test of vocabulary.
Modern classification uses a two word naming convention called binomial nomenclature.
The first word identifies the genus.
Second word sometimes describes a characteristic of the organism and is called specific epithet.
A scientific name is a combination of the genus + specific epithet.
Question
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Question No. 2 of 10
Instruction: (1) Read the problem statement and answer choices carefully (2) Work the problems on paper as needed (3)
Pick the answer (4) Go back to review the core concept tutorial as needed.
Question 2. Which of the following statements is not a function of the science of Taxonomy?
(A)
(B)
(C)
(D)
Bring order out of apparent random information.
Make predictions from conclusions based on organization.
Identify and name new and unknown organisms.
Establish the genotype of an organism.
Question
A. Incorrect!
One of the functions of the field of Taxonomy is to organize information.
B. Incorrect!
One of the functions of the field of Taxonomy is to draw conclusions from the information once it is
organized in comprehensible units.
C. Incorrect!
The identification and naming of new organisms is a very important part of Taxonomy.
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D. Correct!
The establishment of an organism’s genotype is a function of the “Genome Sequencing” scientist.
Taxonomists sequence DNA’s and proteins to be able to classify them not as an end in it self.
Answers A, B and C are all goals of the field of Taxonomy. Answer D uses the information from gene
and protein sequencing however that is the objective of Taxonomy.
Question
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Question No. 3 of 10
Instruction: (1) Read the problem statement and answer choices carefully (2) Work the problems on paper as needed (3)
Pick the answer (4) Go back to review the core concept tutorial as needed.
Question 3. Why is Latin used as taxonomic nomenclature?
(A)
(B)
(C)
(D)
Because Latin is the foundation for all science language.
Because Latin was the language of the founder of Taxonomy.
Since Latin is no longer spoken it is not changing.
Latin uses a familiar alphabet.
Question
A. Incorrect!
This answer is somewhat deceptive. Latin is the foundation of written science in general. However that
is not the reason it continues to be used. Why did Latin take this prominent position?
B. Incorrect!
Linnaeus (born in Sweden) is credited with founding the system we use today to classify organisms. His
native language was Swedish.
C. Correct!
Latin is no longer evolving because it is not spoken. This means that there will be no changes in the
language that impacts the naming convention.
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D. Incorrect!
Latin does use the common alphabet.
Latin is the basis for scientific names. Latin is used because it is no longer a spoken language and so is
not longer evolving and changing. Latin is considered a “dead language” and is static.
The first letter of the genus name is uppercase and the first letter of the specific epithet is lowercase.
Latin based scientific names are precise science and can be used to draw conclusions. Unlike common
names which can be miss leading. For instance a seahorse is neither a fish nor a horse.
Question
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Question No. 4 of 10
Instruction: (1) Read the problem statement and answer choices carefully (2) Work the problems on paper as needed (3)
Pick the answer (4) Go back to review the core concept tutorial as needed.
Question 4. The purpose of DNA sequencing of ribosomal RNA with respect to taxonomy is _____?
(A)
(B)
(C)
(D)
Used to place microbes in an evolutionary time frame.
A measure in the change of an essential trait between microbes.
To bring a systematic and measurable parameter to microbe classification.
All of the above
Question
A. Incorrect!
This answer is partially correct but not the best response.
B. Incorrect!
This answer is partially correct but not the best response.
C. Incorrect!
This answer is partially correct but not the best response.
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D. Correct!
This is the best answer. All of the responses A-C are only partially correct.
rRNA sequencing provides a phylogenetic measure of similarities and changes between organisms. The
closer two organisms are the fewer changes are in the sequence. Conversely the further apart two
organisms are on the taxonomic tree the greater the changes in DNA sequence exist.
Question
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Question No. 5 of 10
Instruction: (1) Read the problem statement and answer choices carefully (2) Work the problems on paper as needed (3)
Pick the answer (4) Go back to review the core concept tutorial as needed.
Question 5. By understanding the binomial naming convention the name Streptococcus pneumoniae tells
us _______?
(A)
(B)
(C)
(D)
That
That
That
That
this
this
this
this
is a Gram-positive organism.
microbe may cause pneumonia.
microbe is rod shaped.
microbe is a bacterium.
Question
A. Incorrect!
The name alone does not indicate if this organism is Gram positive or Gram negative.
B. Correct!
The second word term, the specific epithet, is often used to indicate the disease that this organism
causes.
C. Incorrect!
The word coccus or cocci would indicate that this organism is round in its shape.
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D. Incorrect!
From the name alone it is not possible to tell if this is a bacterium.
The name Streptococcus pneumoniae is a scientific name for a common bacterium that causes
pneumonia and can be very serious in the young and old and it also causes middle ear infections.
Latin based scientific names can provide a significant amount of information. Even in the absence of any
additional information you know a lot about this organism.
Question
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Question No. 6 of 10
Instruction: (1) Read the problem statement and answer choices carefully (2) Work the problems on paper as needed (3)
Pick the answer (4) Go back to review the core concept tutorial as needed.
Question 6. A cladogram is _____.
(A)
(B)
(C)
(D)
The same as a pedigree.
The study of evolutionary relatedness.
Statistical inferences.
A graph that shows the relationship (including genetic) between microbes.
Question
A. Incorrect!
Pedigree is similar but does not depict “clades”. Pedigrees usually show direct parentage.
B. Incorrect!
This is phylogenetics which treats a species as a group of lineage-connected individuals over time.
C. Incorrect!
Statistical inferences (also known as Bayesian inferences) is a mathematical method that is applied to
data to determine the probability of the hypothesis being correct.
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D. Correct!
A cladogram is a diagram that showing relationships between organisms.
other types of relationships.
These can include genetic or
A cladogram is a diagram that shows the relationships between organisms. Order of branching is
significant.
An example of a clade: vertebrates make up a clade; tetrapods (vertebrates that have four limbs)
form their own clade within the vertebrate clade. In the example of vertebrates the “primitive clade is
Vertebrate” and the “derived” or “advanced” clade would be the tetrapods.
Question
Example cladogram fungus Trichoderma. In these two cases you can see that the difference is based on
DNA sequence changes. At the base of each image is a key that shows how many changes are in a
given step length.
Image: http://ars.usda.gov/images/docs/10920_11114/Phylogeny.jpg
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Question No. 7 of 10
Instruction: (1) Read the problem statement and answer choices carefully (2) Work the problems on paper as needed (3)
Pick the answer (4) Go back to review the core concept tutorial as needed.
Question 7. The two domain system: Prokaryote and Eukaryote was changed to the three domain
system: Bacteria, Archaea and Eukarya. What was the main basis for this change in Domain
assignment?
Question
(A)
(B)
(C)
(D)
The sequencing of the 16S rRNA gene.
The discovery that bacteria live in extreme environments.
The differences in cell membranes between bacteria and Archaea.
All of the above.
A. Incorrect!
This information was important in establishing the differences between bacteria and Archaea but was not
the sole fact for creation of a new division.
B. Incorrect!
This discovery was important however there is some overlap in niches of bacteria and Archaea so this
alone is not correct.
C. Incorrect!
There are differences in some membrane linkages and components such as imbedded proteins.
However significant differences are seen within bacteria as well, e.g. Gram Negative versus Gram
Positive.
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D. Correct!
All of the observations made on the differences between bacteria and extremeophiles were necessary to
determine that the requirement for a new division of Archaea.
The three-domain system was created by Carl Woese in the 1970’s. Based on many observations
including the most significant which was the sequence of the 16S rRNA gene. He split the Prokaryota
domain into Eubacteria and Archaebacteria. Their genetic sequences indicated that each of these
Domains arose separately from an ancestor. The Domains were renamed: Bacteria, Archaea and
Eukarya.
While the majority of taxonomists concur with this new assignment of domains it is not universally
accepted.
Kingdoms fall within three Domains: Bacteria, Archaea and Eucarya
Question
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Question No. 8 of 10
Instruction: (1) Read the problem statement and answer choices carefully (2) Work the problems on paper as needed (3)
Pick the answer (4) Go back to review the core concept tutorial as needed.
Question 8. Which of the statements below best describe why ribosomal RNA is considered a
“chronometer of change”?
(A)
(B)
(C)
(D)
It is easy to sequence.
The genetic changes correspond to a measurable time frame.
It is only in organisms of branching interest.
Can perform many and different biochemical roles depending on the class it is in.
Question
A. Incorrect!
The ease or lack of ease in sequencing a gene is not related to how good a genetic marker it is for a
specific trait.
B. Correct!
Genetic change that is consistent over time is important if it is to be used as a measure. Random
changes over time would not make it a good measure.
C. Incorrect!
One of the important properties of a good chronometer is that it be widely distributed over all divisions.
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D. Incorrect!
In order to be useful measure the target protein, or enzyme must perform the same or nearly the same
function in all cells. If this were not the case it is possible that changes are based on selective
advantages generated by the difference in function.
Ribosomal RNA is considered a good chronometer of change because: it is widely distributed, has the
same functions in all organisms and the rate of change corresponds to measurable time.
Question
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Question No. 9 of 10
Instruction: (1) Read the problem statement and answer choices carefully (2) Work the problems on paper as needed (3)
Pick the answer (4) Go back to review the core concept tutorial as needed.
Question 9. RNA polymerase is an enzyme that makes tRNA, mRNA and rRNA from DNA.
Which of the following statements is most accurate?
(A)
(B)
(C)
(D)
Question
Bacteria and Archaea both have one RNA polymerase and they are nearly the same.
Bacteria and Archaea both have one RNA polymerase but they are not the same.
Eukarya has three RNA polymerases, one from each of bacteria, eukarya and its own novel one.
RNA polymerase is a change “chronometer”. Eukarya, bacteria and Archaea have nearly the
same RNA polymerases.
A. Incorrect!
The first half of the statement is true. Archaea and Bacteria both have one RNA polymerase. But they
are not the same. That of Archaea is more closely related to Eukarya.
B. Correct!
Both Archaea and bacteria have one RNA polymerase with the same function. But genetically they are
very different from each other.
C. Incorrect!
There is a similarity between the one RNA polymerase that Arachaea has and that of eukarya but that is
the only correct aspect of this statement.
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D. Incorrect!
RNA polymerase is used to measure the change over time. However the structure does not need to be
identical rather the function needs to be similar, which is the case with the RNA polymerases in all three
divisions.
RNA polymerase is an enzyme that is absolutely essential for the survival of the organism. And the
function is maintained between organisms in the different Division. Because of the essential nature of
the RNA polymerase tracking any changes in its structure or function is a useful tool to tracking
evolutionary processes.
Question
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Question No. 10 of 10
Instruction: (1) Read the problem statement and answer choices carefully (2) Work the problems on paper as needed (3)
Pick the answer (4) Go back to review the core concept tutorial as needed.
Question 10. Definition of species in asexually reproducing organisms.
(A)
(B)
(C)
(D)
(E)
Produce viable and fertile offspring.
Organisms having >97% identical sequences and 70% DNA:DNA homology.
Microbes that inhabit and function virtually identically.
Belong on the same branch of a phylogenetic tree.
None of the above
Question
A. Incorrect!
This is the definition for “sexually” reproducing organisms.
B. Correct!
In asexual organisms it can be difficult to define species. However those individuals having more then
97% identical gene sequences and a DNA to DNA hybridization homology of 70% are considered to be of
the same species.
C. Incorrect!
Organisms with a great deal of genetic diversity can inhabit the identical or nearly identical niches yet be
substantially different on the genetic level.
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D. Incorrect!
The branches on the trees are further broken down into more refined groups. As such you may have
more then one species on any given branch.
In asexual organisms it can be difficult to define species because the definition was originally coined to
apply to only sexually reproducing species. That is a species in sexually reproducing organisms are said
to belong to the same species if their offspring are viable and fertile.
In organisms that are asexual individuals having more then 97% identical gene sequences and a DNA to
DNA hybridization homology of 70% are considered to be of the same species.
Question
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