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