Mastering Micro Exam 3
Reverse transcriptase is a(n) A) RNA-dependent DNA polymerase B) DNA-dependent RNA polymerase C) RNA-dependent RNA polymerase D) DNA-dependent DNA polymerase
A) RNA-dependent DNA polymerase
What is transferred during bacterial conjugation? A) a bacterial plasmid B) a bacterial chromosome C) RNA D) a conjugation pilus
A) a bacterial plasmid
Chemical reactions involving _____ have been proposed as energy-yielding reactions for primitive organisms. A) Fe, O2, and H2 B) S and H2 C) S, O2, and H2 D) S and O2
B) S and H2
Genes that change over evolutionary time as organisms diverge are called orthologs. Organisms with identical or very similar orthologous genes belong to the same __________. A) genotype B) phylotype C) phenotype D) ribotype
B) phylotype
When genetic code is degenerate. Which of the following answers describes an example of the degenerate nature of the code? A) AUU codes for Ile in a wide variety of species B) the sequence "AUGCCGAUU" is read as three codons, AUG, then CCG, then AUU C) AUU, AUC, and AUA all code for Ile D) there are not pauses or commas in the code
C) AUU, AUC, and AUA all code for Ile
The major source of carbon was ______ for early cells and the major fuel for energy was _______ for early cells. A) O2; CO2 B) CO2; N2 C) CO2; H2 D) N2; H2
C) CO2; H2
The diversity of microorganisms in culture collections is representative of the diversity in microorganisms found in nature. TRUE or FALSE
False
The earliest nucleic acid was probably a simple DNA molecule. TRUE or FALSE
False
_________ and _______ transducing phages are distinguished form one another based on their selectivity of which regions are transferred
Generalized / Specialized
How is a mutation distinguished from the broader concept of "DNA damage"?
Mutations are always heritable
The 16S rRNA sequence is an approximately 1,500 bp linear strand of single stranded RNA. TRUE or FALSE
False
___________ genes are those that have been inherited by different species from a common ancestor.
Homologous
References concentration of viruses
Titer
Oxygen did not accumulate in the early atmosphere until it reacted with reduced materials, especially _______, in the oceans. A) ferrous iron B) hydrogen C) elemental sulfur D) nitrate
A) ferrous iron
Which fluorescent molecule enables visualization of living organisms? A) GFP B) acridine orange C) DAPI D) SYBR Green
A) GFP
Viruses rely on the host cell machinery to make new viruses, but they sometimes provide their own enzymes (such as reverse transcriptase, which is an RNA-dependent DNA polymerase). Which of the following types of enzymes would a virus need to provide in order to replicate within a cell? In other words, which of these enzymes would not normally be found in a cell unless a virus provided it? A) RNA replicase (RNA-dendent RNA polymerases) for RNA viruses B) DNA-dependent DNA polymerases for DNA viruses C) DNA-dendent RNA polymerases for DNA viruses D) DNA-dependent RNA polymerases for RNA viruses
A) RNA replicase (RNA-dendent RNA polymerases) for RNA viruses
Which of the following groups contains some representatives with genomes that are so small that they may have as few as two genes? A) RNA viruses B) bacteria C) DNA viruses D) eukaryotes
A) RNA viruses
When determining the number of bacterial virus particles in a suspension, why is the number obtained always less than the actual viral titer? A) because all of the virus particles do not infect with 100% efficiency B) because the cells used for culturing the virus may become resistant to the virus C) because it can be difficult to accurately count all of the plaques produced by infection D) because there may not be enough cells for each viral particle to infect
A) because all of the virus particles do not infect with 100% efficiency
A new chemotherapeutic agent is developed that alters the structure of all thymines in DNA. These thymines are then misread during the production of mRNA. Which of the following could NOT result from this type of mutation? A) frameshift mutation B) missense mutation C) silent mutation D) nonsense mutation
A) frameshift mutation
Which process listed below does NOT require homologous recombination to maintain the new genetic material in the recipient cell? A) gene transfer through a genetic transfer agent B) transformation of a linear piece of DNA C) transduction by a dsDNA phage Mu D) conjugation of linear piece of DNA
A) gene transfer through a genetic transfer agent
The designations Phe-, Leu-, and Ser+ refer to an organism's A) phenotype B) mutation type C) genotype D) plasmid type
A) phenotype
What most occur before new viruses are released from host cell?
Attachment, Assembly, Injection
A NASA ecologist wants to design an instrument to send to Mars on the next space probe to determine whether living organisms ever carried out carbon fixation on that planet. Suggest an assay that she could use on Martian soil samples. A) 34S/35S stable isotope analysis B) 13C/12C stable isotope analysis C) NanoSIMS D) MAR-FISH
B) 13C/12C stable isotope analyiss
Which of the following attaches the target gene to a desired location? A) plasmids B) DNA ligase C) chromosomal DNA D) restriction enzymes
B) DNA ligase
The most widely used molecule in sequence-based evolutionary analyses are _____ genes. A) ATPase B) SSU rRNA C) tRNA D) electron transport
B) SSU rRNA
There is a small lake on campus that students like to use for recreational activities. A study has begun on the microbial community in the lake at different times of the year. In order to quickly determine the approximate number of reproducing bacteria in a sample, it would best to use __________. A) a fluorescent nucleic acid stain B) a fluorescent viability stain C) green fluorescent protein reporter genes D) a gram stain
B) a fluorescent viability stain
Which of the following populations would be most likely to demonstrate genetic drift? A) a large population of bacteria is grown over an extended period in a continuous culture B) a researcher transfers bacteria into fresh medium but accidentally collects only a very small quantity of bacteria in the process C) someone takes an extended course of antibiotics, leaving a relatively small number of surviving bacteria D) a research performs a Gram strain to separate gram-positive and gram-negative bacteria; he places the gram-positive bacteria in one test tube and the gram-negative bacteria in the other
B) a researcher transfers bacteria into fresh medium but accidentally collects only a very small quantity of bacteria in the process
Which technique would be used to estimate the concentration of naturally occurring Escherichia coli in a wastewater sample? A) cell tagging using GFP method B) laser tweezer method C) most probable number (MPN) method D) agar dilution tube method
C) most probable number (MPN) method
A change in the base sequence of DNA that is passed on to daughter cells is __________. A) lethal B) a mistake C) of no consequence D) a mutation
D) a mutation
A "point mutation" refers to mutations involving A) a base-pair substitution B) the gain of a base pair (micro insertion) C) the deletion of a base pair (micro deletion) D) a substitution, deletion, or addition of one base-pair
D) a substitution, deletion, or addition of one base-pair
Scientists believe life may have begun as an RNA world because _________. A) RNA is essential to processes found in all cells B) RNA can bind small molecules C) RNA can have catalytic activity D) all of the listed responses are correct
D) all of the listed responses are correct
When describing the viral genome, which terms could be used? A) ds RNA B) ss DNA C) ds DNA D) all of the listed responses are correct
D) all of the listed responses are correct
An organism that cannot synthesize methionine is called ______. A) a mutant B) a prototroph C) an autotroph D) an auxotroph
D) an auxotroph
The term "phage" is generally reserved for the viruses that infect A) plants B) multiple species C) animals D) bacteria
D) bacteria
The element(s) that have proven useful for stable isotope studies are A) carbon D) nitrogen C) sulfur D) carbon, nitrogen, and sulfur
D) carbon, nitrogen, and sulfur
The killing of cells by UV irradiation involves A) formation of purine dimers B) absorption at 260 nm by proteins only C) absorption at 260 nm by RNA only D) formation of pyrimidine dimers
D) formation of pyridine dimers
Transformation is a useful technique for making genetically modified bacteria in the laboratory. There have been efforts to transform Archaea, but it has been more difficult than transforming Bacteria. One reason that it has been difficult is that Archaea lack a peptidoglycan cell wall. Why does that affect the ability of researchers to develop techniques to transform them? A) relatively few viruses have been identified that infect Archaea B) many archaea are extremophiles and require conditions that are difficult to create in the lab C) it is difficult to create auxotroph stains of Archaea D) genes for resistance to penicillin and related antibiotics can't be used as selectable markers
D) genes for resistance to penicillin and related antibiotics can't be used as selectable markers
All unicellular organisms belong to the same domain of life. TRUE or FALSE
False
At present there are four phyla in the domain Bacteria. TRUE or FALSE
False
In specialized transduction, virtually any genetic marker can be transferred form donor to recipient. TRUE or FALSE
False
Laboratory-based genetic systems have been difficult to develop for Archaea, because they do NOT naturally undergo conjugation or transduction. TRUE or FALSE
False
Lysogeny is unique to bacteriophages; similar relationships have not been found among the animal viruses. TRUE or FALSE
False
Once a putative pure culture has been obtained from the environment, it is no longer necessary to check its purity. TRUE or FALSE
False
Penetration requires that the entire virus is inserted within the host. TRUE or FALSE
False
Penicillin selection is a positive selection for the isolation of mutants with growth factor requirements. TRUE or FALSE
False
Sequencing technology and molecular phylogenetic analyses have had very little impact on our understanding of the evolution and diversity of life on Earth. TRUE or FALSE
False
What is the virus that has killed the most people?
Influenza A
An effective way of growing an animal virus
Primary Cell Culture
The first self-replicating systems likely contained what molecules as a central component?
RNA
A lytic infection results in death of a host cell. TRUE or FALSE
True
In natural samples it is often difficult to differentiate live cells from dead cells or cells from nonliving matter. TRUE or FALSE
True
Intercalating agents, like acridine orange and ethidium bromide, lead to mutagenesis by pushing DNA base pairs apart, which can lead to insertions or deletions. TRUE or FALSE
True
Oxygen was a driving factor in the formation of eukaryotic cells. TRUE or FALSE
True
Several fluorogenic dyes can be used simultaneously in a sample as long as they each emit light at a different measurable wavelength. TRUE or FALSE
True
The establishment of DNA as the genome of the cell may have resulted from the need to store genetic information in amore stable for than RNA. TRUE or FALSE
True
During the 1970s, _____________ pioneered the use of SSU rRNA gene sequencing to be used for distinguishing among taxa.
Carl Woese
A key concept in evolution is that all mutations are A) either deleterious or beneficial B) neutral C) deleterious D) random
D) random
Some viruses have plus sense RNA genomes. Which of the following could describe one of the viruses? A) a virus that contains RNA with the same nucleotide sequence as the functional mRNA that its host cell will translate to produce viral proteins B) a virus that has single-stranded DNA with the same nucleotide sequence as the function mRNA that its host cell will translate to produce viral products C) a virus that has single-stranded DNA with the complementary nucleotide sequence to the functional mRNA that its host cell will translate to produce viral products D) a virus that contains RNA with the complementary nucleotide sequence to the functional mRNA that its host cell will translate to produce viral products
A) a virus that contains RNA with the same nucleotide sequence as the functional mRNA that its host cell will translate to produce viral proteins
Why would it be highly advantageous to a cell to form a mutualism with a prokaryote capable of aerobic cellular respiration? A) aerobic cellular respiration involves an electron transport chain with oxygen as the terminal electron; this produces large amounts of ATP as the electron transport chain produces the greatest amount of ATP in cellular respiration B) a prokaryote capable of aerobic cellular respiration is capable of producing organic materials, such as sugars, using lit energy C) having a symbiotic prokaryote increases the genetic diversity of the cell D) a symbitotic prokaryote increases the nutritional diversity of the organism, greatly increasing possible food sources
A) aerobic cellular respiration involves an electron transport chain with oxygen as the terminal electron; this produces large amounts of ATP as the electron transport chain produces the greatest amount of ATP in cellular respiration
What are the minimal components needed for a virion? A) capsid and genome B) capsid C) genome and envelope D) capsid, genome, envelope
A) capsid and genome
You are studying 12 new isolates from the human skin. The isolates have 16S rRNA sequences that are 97% similar and share important phenotypic traits. Their genomes have 55% of their genes in common. The isolates would most likely be A) classified as individual species of the same genus B) split into different families C) classified as the same species if they can mate via conjugation D) classified as individual strains of the same species
A) classified as individual species of the same genus
Which statement about conjugation is false? A) conjugation is a process of bacterial reproduction B) after conjugation, each cell involved has a copy of the shared DNA C) E. coli is the model for bacterial conjugation
A) conjugation is a process of bacterial reproduction
A transducing phage A) contains fragments of the host chromosome instead of the viral genome B) has a viral coat made of host proteins C) is a lysogenic bacteriophage D) cannot infect new host cells
A) contains fragments of the host chromosome instead of the viral genome
Microinsertions and micro deletions often result in _________ mutations. A) frameshift B) advantageous C) silent D) auxotrophic
A) frameshift
For microbial biodiversity studies, it is common to identify the ________ rather than the ________ as a measure of biodiversity. A) genes / organisms themselves B) cell types / genes C) organisms themselves / genes D) cell types / organisms themselves
A) genes / organisms themselves
What characteristics make a gene a good candidate for determining the evolutionary relationship between organisms? A) highly conserved and universally distributed B) universally distributed C) transferred horizontally between species D) highly conserved
A) highly conserved and universally distributed
A silent mutation is named so because ____________. A) it has no effect on the overall amino acid sequence B) it results from the deletion of DNA, thus silencing the gene C) it causes a frameshift, thus altering protein structure D) it results in a premature termination of the amino acid sequence
A) it has no effect on the overall amino acid sequence
The term axenic is used to describe a(n) A) pure culture B) anoxygenic culture C) anaerobic culture D) nutritionally deficient culture
A) pure culture
Phylogenetic stains, such as those used in FISH, hybridize with A) ribosomal RNA B) mitochondrial DNA C) RNA polymerase D) nuclear DNA
A) ribosomal RNA
Metagenomics involves the analysis of a microbial community by __________. A) sampling and sequencing all of the genes in an environment B) generating a phylogenetic tree based on all of the versions of a gene in an environment C) generation a complete sequence of the genomes of all of the organisms in an environment D) sequencing all of the community RNA in an environment
A) sampling and sequencing all of the genes in an environment
When a transducing phage interacts with a new host cell, A) the DNA fro the previous host can recombine with the new host chromosome B) it will cause the new cell to produce more transducing phage C) the new host cell will be lysed
A) the DNA fro the previous host can recombine with the new host chromosome
When dealing with stable isotopes, enzymes tend to favor A) the lighter isotope B) either the lighter or the heavier isotope, depending on environmental conditions C) the heavier isotope D) the isotopes in about equal proportions
A) the lighter isotope
A single base substitution happens to cause a nonsense mutation early in the gene for a protein. What will be the result? A) the protein will be truncated so much that it is unlikely to function normally B) the protein will be truncated a great deal, but it is likely to function normally C) the protein will be truncated a small amount, but it is unlikely to function normally D) the protein will be truncated a small amount, but it is likely to function normally
A) the protein will be truncated so much that it is unlikely to function normally
In a culture of bacteria, there are some individuals that are unable to synthesize histidine. What is the best and most likely description of how these individuals differ from the other bacteria in the culture? A) they differ in their genotype and in their phenotype B) they differ in their genotype but not in their phenotype C) they differ in their phenotype but not in their genotype D) they don't differ in genotype or phenotype
A) they differ in their genotype and in their phenotype
Frameshift mutations can be very severe. What is one reason why they are often so serious? A) when a frameshift mutation occurs it causes changes in many bases downstream and can affect many of the amino acids in the protein B) frameshift mutations always occur in the regulatory region, so they cause a gene to be turned off and then the protein is not produced at all C) when a frameshift mutation occurs, it causes transition mutations to occur; these are particularly severe D) when a frameshift mutation occurs, it causes changes in many bases upstream and can affect many of the amino acids in the protein
A) when a frameshift mutation occurs it causes changes in many bases downstream and can affect many of the amino acids in the protein
What is the benefit, for a virus, to be temperate or lysogenic virus? A) a single infection event can produce hundreds of new viral particles B) a single infection event can produce millions of new viral particles instead of hundreds of viral particles C) a single infection even can allow other host cells to be infected by the same virus D) a single infection event can allow the virus to live in the host cell indefinitely
B) a single infection event can produce millions of new viral particles instead of hundreds of viral particles
Winogradsky columns are used primarily for enrichment of A) anaerobic cultures, although occasionally aerobes do appear B) aerobes, anaerobes, and phototrophs C) aerobic cultures, although occasionally anaerobes do appear D) phototrophs, although occasionally heterotrophs do appear
B) aerobes, anaerobes, and phototrophs
The introductory passage suggests that selection on mutation rate—from rapidly mutating ssRNA viruses to slower dsDNA viruses—may have been a critical step in the evolution of more stable DNA-based genomes, and subsequently first cells. However, if viruses were able to infect the vast majority of host cells, evolution would have stalled. According to the chapter, what is one way that cells have evolved to avoid viral infection? A) a mutation in the host blocks ribosomal translation, so the host cannot produce the capsid proteins necessary to carry viral DNA B) an attachment receptor on the host cell surface that is recognized by the virus is mutated, making the host resistant to infection C) cells undergo a phenomenon called circular permutation, where the same set of genes is arranged differently in each individual, so the virus is unable to integrate itself D) The host develops restriction endonucleases to cleave foreign viral RNA after it is injected into the cell
B) an attachment receptor on the host cell surface that is recognized by the virus is mutated, making the host resistant to infection
Analyses of sulfur isotopes have been used as evidence against life on the Moon, because the sulfides in lunar rocks have A) exactly equal amounts of 34S and 32S B) an isotope composition similiar to igneous rocks C) an isotope composition similar to marine mud, which is depleted in 34S D) an isotope composition similiar to marine sulfate, which is enriched in 34S
B) an isotope composition similiar to igneous rocks
Mutations contribute to the vast diversity of viruses. What viral genetic type has the most stable genome and the lowest mutation rate? A) single-stranded RNA virus B) single-stranded DNA virus C) double-stranded DNA virus D) double-stranded RNA virus
C) double-stranded DNA virus
What must occur for bacterial conjugation to take place? A) the cells must transfer RNA B) each cell must contain a plasmid C) the cells must come into contact with each other D) one of the cells must be E. coli
C) the cells must come into contact with each toher
Phylogenetic trees for bacteria are constructed by which of the following? A) examining morphological, nutritional, and biochemical similarities to determine which individuals appear to be the most similar B) analyzing molecular similarities and then using computer algorithms or optimally criteria to construct phylogenetic trees showing hypothesized evolutionary relationships C) examining the amount of horizontal gene transfer; those organisms that exchange the largest amounts of genetic material in this manner are the most closely related D) placing organisms with the most similar characteristics together; these organisms show convergent evolution and therefore belong together in the phylogeny
B) analyzing molecular similarities and then using computer algorithms or optimally criteria to construct phylogenetic trees showing hypothesized evolutionary relationships
You would like to determine the rate of production of carbon dioxide in a specific microbial habitat. How could you do this without growing the microorganisms in the lab? A) by using radioisotope-labeled carbon dioxide B) by using a microsensor C) by using radiolabeled methane D) by using radiolabeled DNA
B) by using a microsensor
Competent cells are cells that A) are killed by heat B) can take up DNA from their surrounding environment and integrate it into their own chromosomes by recombination C) have the ability to produce capsules D) are also considered "rough-strain" based on colony phenotype
B) can take up DNA from their surrounding environment and integrate it into their own chromosomes by recombination
How do complex transposons differ from simple transposons? A) complex transposons code for transposes; simple transposons do not B) complex transposons code for additional genetic elements, such as antibiotic resistance genes; simple transposons only code for the transposes gene essential for the transposon itself C) complex transposons are found in multiple locations in the target DNA; simple transposons are found only in one location
B) complex transposons code for additional genetic elements, such as antibiotic resistance genes; simple transposons only code for the transposes gene essential for the transposon itself
Metatranscriptomics and metaproteomics are favored over metagenomics when ________ is of more interest than ________. A) phylogeny / gene presence B) function or gene expression / gene presence C) gene presence / function or gene expression D) gene presence / phylogeny
B) function or gene expression / gene presence
Microarrays are useful for assessing A) the presence of specific rRNA sequences B) gene expression and the presence of specific rRNA sequences C) gene expression D) enzymatic activity
B) gene expression and the presence of specific rRNA sequences
Culture-independent approaches avoid issues associated with A) next generation sequencing B) growing organisms in the lab C) detecting very rare phylotypes D) conflating phylogenetic and functional diversity
B) growing organisms in the lab
Based on your knowledge of cellular and viral processes, which of the following would be (an) appropriate target(s) for antiviral drugs? A) aminoacyl-tRNA synthetases and ribosomes B) integrases C) aminoacyl-tRNA synthetases D) ribosomes
B) integrases
If a bacterium carrying a plasmid that confers resistance to ampicillin is placed into medium without ampicillin, it may A) transfer resistance to other cultures in the laboratory B) lose the plasmid because there is no selection for ampicillin resistance C) undergo a reversion mutation D) gain resistance to other antibiotics
B) lose the plasmid because there is no selection for ampicillin resistance
Both deletions and insertions occur during the evolution of microbial genomes. Insertions bring in new genes that may be useful for the cell, but deletions A) are uncommon because they are usually lethal B) may increase fitness of a microorganism by eliminating unneeded genes C) always result in a severe loss of fitness for the microorganism D) always result in a severe loss of fitness but keep microbial genomes compact
B) may increase fitness of a microorganism by eliminating unneeded genes
Which taxonomic tool would scientists use if they wanted to determine if an outbreak of food poisoning was caused by a particular strain of a pathogen? A) DNA:DNA hybridization B) multilocus sequence typing C) fatty acid methyl ester analysis D) fluorsence in situ hybridization
B) multilocus sequence typing
The mutagens 2-aminopurine and 5-bromouracil are examples of A) chemicals reacting with DNA B) nucleotide base analogs C) alkylating agents D) none of the answers are correct
B) nucleotide base analogs
Evolution is driven by A) selection pressure B) selection pressure applied to random mutation C) random mutation D) novel metabolic pathways
B) selection pressure applied to random mutation
Consider a mutation in which the change is from UAC to UAU. Both codons specify the amino acid tyrosine. Which type of point mutation is this? A) nonsense mutation B) silent mutation C) frameshift mutation D) missense mutation
B) silent mutation
Microorganisms were probably restricted to the oceans and subsurface environments until A) aquatic life brought them onto land B) the ozone layer was made C) phototorophy evolved D) chemoorganotrophy developed
B) the ozone layer was made
How do restriction enzymes cut DNA sequences? A) they have the ability to cut DNA randomly B) they cut DNA at sites, called recognition sites, that have specific nucleotide sequences C) they cut DNA at sequences that have lots of adenine bases
B) they cut DNA at sites, called recognition sites, that have specific nucleotide sequences
Increasing genetic variability by the uptake of DNA form the environment is _________. A) transduction B) transformation C) a mutation D) conjugation
B) transformation
Enrichment cultures are often effective for isolating bacteria from complex communities in natural samples because they __________. A) select for certain bacteria B) select against certain bacteria C) select for and against certain bacteria D) do not select for or against any bacteria; they help every organism to grow
C) select for and against certain bacteria
Mice that are injected with only the R strain of Streptococcus pneumoniae A) become sick for prolonged periods of time B) are killed, because R strain cells are deadly C) stay healthy, because their immune systems can kill this strain easily
C) stay healthy, because their immune systems can kill this strain easily
Molecular sequencing suggests that mitochondria arose from a group of prokaryotic organisms within the A) cyanobacteria B) Crenarchaeota C) Proteobacteria D) iron-oxidizing bacteria
C) Proteobacteria
Which finding is most surprising from Griffith's experiments? A) S strain cells kill the mice B) R strain cells fail to produce a capsule C) S strain cells are isolated from the blood of mice infected with heat-killed S strains and live R strains D) S strains are able to escape phagocytosis
C) S strain cells are isolated from the blood of mice infected with heat-killed S strains and live R strains
ALL viral particles A) exhibit cell lysis under a particular condition B) are smaller than bacterial cells C) are metabolically inert D) contain an envelope to prevent its degradation outside of a host
C) are metabolically inert
The earliest RNA probably functioned in A) neither catalysis or self-replication B) catalysis C) both catalysis and self-replication D) self-replication
C) both catalysis and self-replication
Which type of transposons would contain a gene for transposase? A) Neither simple nor complex transposons; the transposase enzyme is coded independently by the cell B) complex transposons C) both simple and complex transposons D) simple transposons
C) both simple and complex transposons
Lysogen probably carries a strong selective advantage for the host cell because it A) prevents cell lysis B) confers resistance to infection by many virus types and prevent cell lysis C) confers resistance to infection by viruses of the same viruses D) confers resistance to infection by viruses of a different type (or strain)
C) confers resistance to infection by viruses of the same viruses
Bacterial conjugation is often referred to as bacterial sex. Why is this term inaccurate? A) sex is a phenomenon only seen in animals B) it does not require two cells to occur C) conjugation does not result in the formation of new offspring D) bacteria are neither male nor female
C) conjugation does not result in the formation of new offspring
What has occurred when organisms share a trait that was NOT inherited from a common ancestor? A) perpendicular evolution B) parallel evolution C) convergent evolution D) divergent evolution
C) convergent evolution
Some viruses, especially animal viruses, have an envelope surrounding their nucleocapsid. This envelope may have viral proteins embedded in it. Why are the viral proteins more readily recognized and targeted by the immune system than the envelope? A) only proteins can stimulate the immune system, so the phospholipids and glycoproteins of the envelope are not immunogenic B) the envelope is not capable of stimulating an immune response because of its makeup C) enveloped viruses are often coated with animal cell membrane as they leave the cell; this membrane is a major component of the viral envelope; the viral proteins are more readily recognized by the immune system, as they are more distinct from the materials normally found in and on the cells; however, the envelope can contain several types of viral components as well D) viral proteins are highly immunogenic in order to facilitate uptake by host cells, while the envelope is not important in uptake by host cells
C) enveloped viruses are often coated with animal cell membrane as they leave the cell; this membrane is a major component of the viral envelope; the viral proteins are more readily recognized by the immune system, as they are more distinct from the materials normally found in and on the cells; however, the envelope can contain several types of viral components as well
A change in allele frequencies in a set of organisms over time is called ________. A) mutation B) selection C) evolution D) fitness
C) evolution
Which molecular method allows for the detection of a specific organism within a diverse microbial community? A) enrichment techniques B) viability staining C) fluorescent in situ hybridization D) fluorescent DNA staining using DAPI
C) fluorescent in situ hybridization
The biggest limitation of traditional light microscopy and electron microscopy methods is that they are unable to reveal A) cellular components of small microbes because of the limits of magnification B) physical microbial interactions as found in nature C) genetic and functional diversity of microorganisms in the habitat under study D) absolute cell concentration
C) genetic and functional diversity of microorganisms in the habitat under study
The pan genome of a microbial species is constantly changing because of A) bottleneck events B) substitution and bottleneck events C) horizontal gene transfer D) substitutions
C) horizontal gene transfer
The science of microbial ecology deals with A) how microbial communities interact with each other and their environment B) microbial activity and biodiversity C) how the activity and biodiversity of microbial communities affect microbial interactions with each other and the environment D) microbial gene regulation mechanisms in response to environmental change
C) how the activity and biodiversity of microbial communities affect microbial interactions with each other and the environment
Viral replication is A) dependent on the host cell's DNA, RNA, enzymes, and metabolism B) independent of both the host cell's DNA and the host cell's enzymes and metabolism C) independent of the host cell's DNA but dependent on the host cell's enzymes and metabolism D) dependent on the host cell's DNA and RNA
C) independent of the host cell's DNA but dependent on the host cell's enzymes and metabolism
The phylogenetic analysis of complex microbial communities often targets small subunit (SSU) ribosomal RNA genes. This is because rRNA is found in all organisms and __________. A) is easier to extract from samples B) has more genes than mRNA C) is highly conserved over evolutionary time D) is made by cells only at certain times
C) is highly conserved over evolutionary time
Which approach would help to identify biologically produced sulfur in a sediment sample? A) microautoradiography B) microelectrodes C) isotopic fractionation D) enrichment
C) isotopic fractionation
Which statement is TRUE? A) viruses do not contain their own nucleic acid polymerases B) all viruses contain their own nucleic acid polymerases C) many viruses contain their own nucleic acid polymerases D) the origins of the nucleic acid polyermases used by viruses and eukaryotic
C) many viruses contain their own nucleic acid polymerases
Select the option that lists the steps necessary for PCR microbial community analysis in the correct order. A) microbial sample collection; sorting by electrophoresis; analysis; DNA extraction; PCR of target genes B) microbial sample collection; PCR of target genes; DNA extraction; sorting by electrophoresis; analysis C) microbial sample collection; DNA extraction; PCR of target genes; sorting by electrophoresis; analysis D) PCR of target genes; microbial sample collection; DNA extraction; sorting by electrophoresis; analysis
C) microbial sample collection; DNA extraction; PCR of target genes; sorting by electrophoresis; analysis
The best choice for estimating the viable cell number of a water sample would be the _______. A) streak plating method B) spectrophotometric method C) most probable number method D) agar dilution tube method
C) most probable number method
What is the process that will amplify DNA from a single cell isolated from a natural microbial community? A) polymerase chain reaction B) polymerase chain amplification C) multiple displacement amplification D) you cannot amplify the DNA from a single cell isolated from an environmental sample
C) multiple displacement amplification
While studying protein synthesis in the lab, you experimentally induce a mutation in a bacterium's DNA. You assess the proteins in the mutated bacterium and find that one of them is significantly shorter than its wild-type counterpart. Based on this information, what type of mutation did you induce? A) silent mutation B) deletion mutation C) nonsense mutation D) missense mutation
C) nonsense mutation
Microarrays that have been designed to screen samples for specific groups of bacteria are called _______. A) biochips B) microchips C) phylochips D) phytochips
C) phylochips
The evolutionary history of a group of organisms is called its _____ and it is inferred from ________. A) phylogeny / phenotype B) taxonomy / phenotype C) phylogeny / nucleotide sequence data D) taxonomy / morphology
C) phylogeny / nucleotide sequence data
Viruses infecting _______ are typically the easiest to grow in the laboratory. A) plants B) fungi C) prokaryotes D) animals
C) prokaryotes
Systematic analysis now commonly includes ________ to identify, characterize, and determine relationships between new strains of bacterial species. A) staining B) microscopy C) pigments D) whole genome analysis
D) whole genome analysis
Which of the following would result in a frameshift mutation? A) the addition of three nucleotides between two existing codon B) the deletion of one nucleotide from one codon and two nucleotides from the adjacent codon C) the deletion of two nucleotides in a codon D) the deletion of three nucleotides in a codon
C) the deletion of two nucleotides in a codon
Plaque assays are often used to estimate the number of virions in a sample of a particular volume (the titer). The count is given as plaque-forming units. Which of the following is NOT generally a concern that must be considered in evaluating the results of plaque assays? A) the plaques must be at a density that can be counted on the plate; high and low densities may result in inaccurate counts B) the plaques must be clearly visible in order to be counted accurately; this technique cannot be used with viruses that do not cause clear cellular damage C) the largest problem is that single viruses may create multiple plaques, resulting in overestimates of the number of viruses present D) the largest problem is that the count may underestimate the total number of viral particles, as not all visions may be able to cause infection
C) the largest problem is that single viruses may create multiple plaques, resulting in overestimates of the number of viruses present
The genes for 16S rRNA are used to determine genetic relatedness because ________. A) these genes are only found in eukaryotes B) these genes have changed a great deal over time C) these genes are of adequate length to show deep relationships D) these genes have different functions in different cells
C) these genes are of adequate length to show deep relationships
In general, how might recombinant DNA technology be used to prevent a genetic disorder caused by a mutation in a single gene? A) to remove an undesirable gene B) to replace a defective gene with a working gene C) to insert a desirable gene, remove an undesirable gene, or replace a defective functioning gene D) to insert a desirable gene
C) to insert a desirable gene, remove an undesirable gene, or replace a defective functioning gene
What is unique about transduction compared to normal bacteriophage infection? A) the bacteriophage takes fragments of the cell with it during transduction B) the bacteriophage does not erupt from an infected cell during transduction C) transduction transfers DNA from the chromosome of one cell to another
C) transduction transfers DNA from the chromosome of one cell to another
Horizontal gene transfer A) occurs within the bacterial species B) only affects the evolution of plasmids C) is so rare over evolutionary history that it is not considered when examining microbial evolution D) complicates the construction of phylogenetic trees and the interpretation of specific traits in relation to evolution
D) complicates the construction of phylogenetic trees and the interpretation of specific traits in relation to evolution
The methodology of microbial ecology includes A) gene, transcript, and protein characterization B) enrichment and isolation of specific microbes C) cell-staining methods D) enrichment and isolation of specific microbes, cell-staining, and gene, transcript, and protein characterization
D) enrichment and isolation of specific microbes, cell-staining, and gene, transcript, and protein characterization
Which of the following statements is FALSE concerning enrichment bias? A) enrichment bias resulted in the underestimation of prokaryotic diversity B) dilution of the inoculum may help to avoid enrichment bias in some cases C) enrichment bias is impossible to overcome in some oligotrophic environments D) enrichment bias favors organisms that grow quickly
D) enrichment bias favors organisms that grow quickly
What technique(s) can be used to characterize the phylogenetic composition of a microbial community without culturing any of the members? A) green fluorescent protein tagging B) radioisotope experiments C) stable isotope techniques D) fluorescent in situ hybridization
D) fluorescent in situ hybridization
How is generalized transduction different from specialized transduction? A) generalized transduction is initiated by a lysogenic bacteriophage; specialized transduction is initiated by a lytic phage B) only one specific host gene is transferred in both specialized transduction and generalized transduction C) specialized transduction uses animal viruses instead of bacteriophage D) generalized transduction is initiated during lytic cycle of a virulent bacteriophage specialized transduction is initiated during the lysogenic cycle of a temperate bacteriophage
D) generalized transduction is initiated during lytic cycle of a virulent bacteriophage specialized transduction is initiated during the lysogenic cycle of a temperate bacteriophage
Why would a recombinant DNA molecule be inserted into a host cell? A) plasmids cannot be isolated outside of a host cell B) it can protect the recombinant DNA C) restriction enzymes can only be used inside of a cell D) it can be copied, transcribed, and translated into a desired protein
D) it can be copied, transcribed, and translated into a desired protein
Why does the structure of plant and bacterial cells illustrate the reason for having few enveloped viruses that infect these cells? A) plant and bacterial cells contain cell walls that prevent viral infection B) plant and bacterial cells contain cell walls that prevent viruses from being released from the cell C) plant and bacterial cells contain cell walls that prevent attachment of viruses D) plant and bacterial cells contain cell walls that limit the virus from budding out and obtaining the envelope
D) plant and bacterial cells contain cell walls that limit the virus from budding out and obtaining the envelope
When solutions of host cells and infectious visions are mixed and spread on an agar plate, _________ from where viruses lyse the host cells. A) prophages B) insertion sequences C) colonies D) plaques
D) plaques
A mutation that readily reverses to restore the original parental type would most likely be due to a(n) A) frameshift mutation B) deletion C) insertion D) point mutation
D) point mutation
Which of the following best explains the endosymbiont hypothesis? A) prokaryotes capable of digestion took up residence in larger prokaryotes, forming obligate mutualisms; the prokaryotes capable of digestion evolved into lysosomes. B) prokaryotes capable of cellular respiration and prokaryotes capable of photosynthesis took up residence in larger prokaryotes, forming obligate mutualisms; the prokaryotes capable of cellular respiration evolved into chloroplasts and the prokaryotes capable of photosynthesis evolved into mitochondria. C) prokaryotes capable of cellular respiration began to associate with prokaryotes capable of photosynthesis; they fused together to form eukaryotic cells. D) prokaryotes capable of cellular respiration and prokaryotes capable of photosynthesis took up residence in larger prokaryotes, forming obligate mutualisms; the prokaryotes capable of cellular respiration evolved into mitochondria and the prokaryotes capable of photosynthesis evolved into chloroplasts.
D) prokaryotes capable of cellular respiration and prokaryotes capable of photosynthesis took up residence in larger prokaryotes, forming obligate mutualisms; the prokaryotes capable of cellular respiration evolved into mitochondria and the prokaryotes capable of photosynthesis evolved into chloroplasts.
What most likely explains the recovery of live S strain cells from a mouse injected with heat-killed S strain mixed with live R strain cells? A) the S strain fused with the R strain, making it resistant B) the R strain cells picked up the capsules from the S strain cells C) the S strain was revived by the presence of the host's immune system D) the R strain picked up the S strain DNA, enabling it to produce a capsule
D) the R strain picked up the S strain DNA, enabling it to produce a capsule
What characteristic of the S strain allows it to evade the immune system of the mice? A) they are naturally competent B) they are resistant to heat C) they are genetically engineered to be resistant to killing D) the cells have a capsule
D) the cells have a capsule
Which statement most closely expresses our present understanding? A) the chloroplast and the cyanobacteria are not closely (or specifically) related B) the chloroplast is an ancestor of the cyanobacteria C) the cyanobacteria are descendants of the chloroplast D) the chloroplast arose from the incorporation of a cyanobacterial-like organism
D) the chloroplast arose from the incorporation of a cyanobacterial-like organism
How do viability stains usually distinguish between living cells and dead cells? A) the dye's fluorescence is quenched by dead cells B) the chemical stain is taken up by living cells and once metabolized becomes fluorescent C) the chemical fluoresces only when bound to ribosomes that are actively synthesizing proteins D) the dye specifically targets intact cytoplasmic membranes
D) the dye specifically targets intact cytoplasmic membranes
Which of the following is NOT a way in which viruses are different from living organisms? A) viruses have DNA or RNA, not both B) viruses are acellular and all living things are made up of cells C) viruses depend on their host to synthesize the essential components of new viruses (eg., genetic material and proteins), while living organisms are capable of synthesizing these components even if they require a host for food, shelter, or other necessities D) viruses are obligate parasites and no living organisms are obligate parasites
D) viruses are obligate parasites and no living organisms are obligate parasites
Which of the following is true about viral infection? A) viruses can infect any cell in a particular species; it does not matter which tissue they infect as long as the species (or group of similar species) is correct B) viruses have what is needed to infect a host cell; they do not need anything specific from the host cell in order to cause infection and therefore can infect a wide range of cells C) viruses can infect any cells within a large group, but they are not more specific than that; for example, there are plant viruses that can affect many types of plants, bacteriophages that affect many types of bacteria, and animal viruses that affect a range of viruses D) viruses are very specific in which cells they infect; for a virus to be taken up by a cell, it must find a cell with appropriate receptors on the surface; it cannot be taken up by cells without the appropriate receptors
DD) viruses are very specific in which cells they infect; for a virus to be taken up by a cell, it must find a cell with appropriate receptors on the surface; it cannot be taken up by cells without the appropriate receptors
The MPN technique is rarely applied in the food industry because any microbial presence in food is unsafe. TRUE or FALSE
False