Mastering Micro Exam 2

In a body of freshwater, the transition between the warmer upper layers and the colder lower layers of water is called the __________. Hints epilimnion thermocline planktonic hypolimnion

thermocline

When is the repressor protein transcribed? It is always transcribed. Only in the absence of tryptophan Only in the presence of tryptopha

It is always transcribed.

In the lac operon, which of the following conditions would allow the structural genes to be transcribed? Hints Glucose is present and lactose is absent. Lactose and glucose are present. Lactose and glucose are absent. Lactose is present and glucose is absent.

Lactose is present and glucose is absent.

The genome sequence of an organism can provide information about the organism's __________. Hints function, size, and evolutionary history genes, size, and function function, evolutionary history, and morphology genes, function, and evolutionary history

genes, function, and evolutionary history

According to ecological theory, each organism has one place where it will be most successful, called the __________. Hints fundamental niche guild microenvironment realized niche

realized niche

Ecologically, which transformation is most important in degrading chlorinated xenobiotics? Hints dechlorination chlorination reductive dechlorination oxidative chlorination

reductive dechlorination

Fungi are __________. Hints chemolithotrophs photosynthetic chemoorganotrophs obtain nutrients through ingestion

chemoorganotrophs

Sequence 16S rRNA amplification

1. isolate DNA 2. amplify 16S gene by PCR 3. run on agarose gel; check for correct size 4. sequence 5. align sequences, generate tree

A soil clump has an oxic (oxygen containing) zone containing aerobic and facultatively aerobic organotrophs, and an anoxic zone containing fermentative bacteria, sulfate reducers, and denitrifyers. This soil clump has at least __________ different habitats, __________ different communities and __________ different guilds. Hints 5, 2, 5 5, 5, 20 2, 2, 20 2, 2, 5

2, 2, 5

Using quorum sensing, how do bacteria know when there are sufficient numbers present to express a specific gene? Hints A high concentration of autoinducer outside the cell triggers the two-component system to turn on transcription of the specific gene. A low concentration of an autoinducer in the cell triggers the two-component system to turn on transcription of the specific gene. A low concentration of an autoinducer outside the cell triggers the two-component system to turn on transcription of the specific gene. A high concentration of autoinducer inside the cell triggers the two-component system to turn on transcription of the specific gene.

A high concentration of autoinducer inside the cell triggers the two-component system to turn on transcription of the specific gene.

The genetic code has many important characteristics. For example, a specific codon always means the same thing in a particular species. Codons mean the same thing in most species (even though there are some exceptions). In some cases, a particular amino acid can be specified by more than one codon (the genetic code is degenerate). Which of the following answers describes an example of the degenerate nature of the code? Hints AUU codes for Ile in a wide variety of species There are no pauses or commas in the code. The sequence "AUGCCGAUU" is read as three codons, AUG, then CCG, then AUU. AUU, AUC, and AUA all code for Ile

AUU, AUC, and AUA all code for Ile

Which of the following is a characteristic of an F+ cell? Presence of a fertility factor Ability to mate with an F- cell Ability to synthesize sex pili, presence of a fertility factor, and ability to mate with an F- cell. Ability to synthesize sex pili

Ability to synthesize sex pili, presence of a fertility factor, and ability to mate with an F- cell.

What structure can the viral genome take? Hints ds-RNA ss-DNA ds-DNA All of the listed responses are correct.

All of the listed responses are correct.

What is the inducer molecule in the lac operon? Repressor proteins Allolactose Glucose Lactose Galactose

Allolactose

In which stage does formation of mature viruses occur? Attachment Assembly Biosynthesis Release Penetration

Assembly

Why is it generally more difficult to effectively treat systemic fungal infections than to treat bacterial infections? Hints Fungi can more rapidly develop resistance to medications than bacteria can. Because fungi are eukaryotes, their cells are more similar to human cells and it is harder to target the fungal cells without causing harm to the human cells. Fungal infections are often on the surface of the body (e.g., ringworm) while bacterial infections are often within the body and more easily treated with oral medication. Because antibiotics are produced by fungi, they are less effective against fungi.

Because fungi are eukaryotes, their cells are more similar to human cells and it is harder to target the fungal cells without causing harm to the human cells.

Which of the following might result in a frameshift mutation? Nitrous acid 5-bromouracil Benzopyrene

Benzopyrene

The host DNA is usually degraded during which stage? Assembly Penetration Biosynthesis Attachment Release

Biosynthesis

Decomposition of organic carbon ultimately results in the formation of __________. Hints CO2 plus CH4 in aerobic environments and CH4 in anoxic environments CO2 in aerobic environments and CH4 in anoxic environments CO2 in aerobic environments and CO2 plus CH4 in anoxic environments CH4 in aerobic environments and CO2 in anoxic environments

CO2 in aerobic environments and CO2 plus CH4 in anoxic environments

In what way(s) are ciliates unique among the protists? Hints Ciliates have two kinds of nuclei. Ciliates are endosymbiotic hosts for various Bacteria, Archaea and microeukaryotes. Ciliates carry out phagocytosis. Ciliates can form symbiotic associations with various animal species.

Ciliates have two kinds of nuclei.

Giardia intestinalis (Giardia lamblia) is a protist that causes giardiasis. Its mitochondria do not have electron transport proteins and citric acid cycle enzymes. What can you infer from this information? Hints G. intestinalis is anaerobic and uses fermentation. G. intestinalis uses photosynthesis. G. intestinalis must acquire oxygen from some external source. G. intestinalis must have a cell wall made of chitin.

G. intestinalis is anaerobic and uses fermentation.

How is generalized transduction different from specialized transduction? Generalized transduction is initiated during lytic cycle of a virulent bacteriophage; specialized transduction is initiated during the lysogenic cycle of a temperate bacteriophage. Specialized transduction uses animal viruses instead of bacteriophage. Generalized transduction is initiated by a lysogenic bacteriophage; specialized transduction is initiated by a lytic phage. Only one specific host gene is transferred in both specialized transduction and generalized transduction.

Generalized transduction is initiated during lytic cycle of a virulent bacteriophage; specialized transduction is initiated during the lysogenic cycle of a temperate bacteriophage.

Some Archaea live in remarkably saline environments. What is the challenge of living in a highly saline environment? Hints In a highly saline environment, most cells desiccate. Extreme halophiles have specialized adaptations to prevent desiccation. In extremely saline environments, salt will move into most cells through diffusion. Because of the influx of salt, the ionic balance within the cell will be disrupted. The high salt concentration will cause water to flow into the cell until it lyses. The high salt concentration will damage the cell wall and cause it to burst.

In a highly saline environment, most cells desiccate. Extreme halophiles have specialized adaptations to prevent desiccation.

Horizontal gene transfer refers to the transfer of genes from one organism to another, as occurs during conjugation between bacteria. How does this differ from vertical gene transfer? Hints In horizontal gene transfer, genes are transferred from one mature adult organism to another. In vertical gene transfer, genes are transferred from adults to offspring. Conjugation can involve horizontal or vertical gene transfer, depending on the physical orientation of the bacteria involved. In vertical gene transfer, genes are transferred by a vector such as a bacteriophage. In horizontal gene transfer, genes are transferred between two organisms of the same species. In vertical gene transfer, genes are transferred between two organisms of different species.

In horizontal gene transfer, genes are transferred from one mature adult organism to another. In vertical gene transfer, genes are transferred from adults to offspring.

Which operons are never transcribed unless activated? Inducible operons Repressible operons Inducible and repressible operons

Inducible operons

What is one piece of evidence for the endosymbiotic hypothesis? Hints There are no mitochondrial/Bacterial genes in the eukaryotic nucleus. Mitochondria have cell walls made of peptidoglycan, like those of Bacteria. Mitochondria have linear DNA. Mitochondria have 70S ribosomes.

Mitochondria have 70S ribosomes.

A farmer wants to stock small fish in a pond on his property, but the water looks a bit murky to him. He asks a microbiologist friend to analyze the pond water to see if fish could survive there. The microbiologist finds that the water has a very high BOD. Should she tell the farmer to stock the pond with fish? Hints Yes; the pond is likely to be aerated. No; the pond is likely to be anoxic. Yes; the pond water is high in nutrition for the fish. No; the pond water is toxic.

No; the pond is likely to be anoxic.

In which stage is the viral DNA introduced into the cell? Release Biosynthesis Assembly Penetration Attachment

Penetration

Which finding is most surprising from Griffith's experiments? S strain cells kill the mice. S strains are able to escape phagocytosis. S strain cells are isolated from the blood of mice infected with heat-killed S strains and live R strains. 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.

Trichomonas vaginalis is an unusual protist because most lack introns. Why is this unusual? Hints T. vaginalis is a eukaryote. While it is common for eukaryotes to lack introns, most protists have them. T. vaginalis is a eukaryote. In most eukaryotes, introns form the most critical part of the gene that is expressed to form a functional product. T. vaginalis is a eukaryote. Introns are sequences generally found in prokaryotes to allow transcription and translation to occur simultaneously. T. vaginalis is a eukaryote. In most eukaryotes, introns (intervening sequences) are removed from RNA during RNA processing.

T. vaginalis is a eukaryote. In most eukaryotes, introns (intervening sequences) are removed from RNA during RNA processing.

Two-component regulatory systems rely on a balance of phosphorylation and dephosphorylation of sensor kinases and response regulators. If the response regulator became permanently phosphorylated due to lack of phosphatase activity, which of the following would NOT happen? Hints The cell would become more sensitive to the environmental stimulus. The cell would become insensitive to the environmental stimulus. The cell would not be able to "reset" its response cycle. The operon controlled by the response regulator would be always transcribed or never transcribed, depending upon the regulatory role of the response regulator.

The cell would become more sensitive to the environmental stimulus.

During conjugation, if an Hfr cell is mated with an F- cell, why will the F- cell remain F-? Hints The recipient will not remain F-; it will become F+. The donor cell is not an F+ cell; it is Hfr. The recipient will not remain F-; it will become Hfr because of the donor cell genome. The cells would not stay in contact long enough for the entire Hfr genome to be transferred.

The cells would not stay in contact long enough for the entire Hfr genome to be transferred.

Which of the following would result in a frameshift mutation? Hints The deletion of three nucleotides in a codon The addition of three nucleotides between two existing codon. The deletion of one nucleotide from one codon and two nucleotides from the adjacent codon The deletion of two nucleotides in a codon

The deletion of two nucleotides in a codon

How can specialized transduction contribute to the transfer of antibiotic resistance genes in a bacterial population? The phage lyses the bacterium and releases resistance genes into the local environment, which can then be taken up by recipient cells. The prophage takes an antibiotic resistance gene with it and is packaged with the newly synthesized viral DNA. The phage causes the destruction of any antibiotic present during the specialized transduction process.

The prophage takes an antibiotic resistance gene with it and is packaged with the newly synthesized viral DNA.

Which of the following genetic elements is transcribed into a single mRNA? The operator The repressor The inducer The structural genes The promoter

The structural genes

What would be the fate of a lytic bacteriophage if the host cell died prior to the assembly stage? The virus would not be able to infect new hosts. The cell could still be revived by the virus. The virus would infect new hosts.

The virus would not be able to infect new hosts

Why is the tryptophan operon turned off in the presence of tryptophan? Tryptophan binds to and activates the repressor proteins; the repressor proteins, in turn, bind to the operator, preventing transcription. Tryptophan is not an important amino acid for cells. Tryptophan can be used over and over again in the cell.

Tryptophan binds to and activates the repressor proteins; the repressor proteins, in turn, bind to the operator, preventing transcription.

Why is U4+ a preferred form of uranium over U6+? Hints Uranite is insoluble; U4+ is soluble. U6+ is insoluble, which makes it difficult to work with. U4+ is soluble, so it can move from its initial site to other places and be diluted by groundwater. U4+ is insoluble, so it will not contaminate groundwater.

U4+ is insoluble, so it will not contaminate groundwater.

Which of the following is NOT a way in which viruses are different from living organisms? Hints Viruses are obligate parasites and no living organisms are obligate parasites. Viruses have DNA or RNA, not both 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 acellular and all living things are made up of cells

Viruses are obligate parasites and no living organisms are obligate parasites.

One group of chemical mutagens includes the base analogs. How do these lead to mutations? Hints They lead to the formation of pyrimidine dimers. Base analogs push apart and distort the double helix. This distortion can lead to insertions and deletions (including frameshift mutations). When replication occurs, complementary base pairing may fail because the base analog may not be treated in the same way as the base that it replaced. They lead to alkylation, which can lead to substitutions.

When replication occurs, complementary base pairing may fail because the base analog may not be treated in the same way as the base that it replaced.

Based on the animation, what is transferred during bacterial conjugation? A conjugation pilus RNA A bacterial chromosome A bacterial plasmid

a bacterial plasmid

A chemical that removes the amine groups from certain nucleotides would be classified as __________. Hints a dimer-forming mutagen a chemical-modifying mutagen a base analog mutagen a intercalating mutagen

a chemical-modifying mutagen

The SOS DNA repair system is __________. Hints error-free repair of large amounts of damage the best way to repair any damage to the genome error-free repair of small amounts of damage a last-ditch effort to prevent cell death from major chromosomal damage

a last-ditch effort to prevent cell death from major chromosomal damage

A change in the nucleotide sequence of DNA that is passed on to daughter cells is referred to as __________. Hints a mutation lethal a mistake of no consequence

a mutation

The field of study that can reveal how genes function, reveal how organisms interact with the environment, and show evolutionary relationships is __________. Hints genomics transcriptomics proteomics comparative genomics

comparative genomics

One way that regulation is often studied is by examining the effects of mutations. For example, mutations within the parts of the lac operon have been well studied. Which of these mutants would be considered a constitutive mutant? Hints a mutation that disables the repressor a mutation in the gene for beta-galactosidase permease a mutation that disables the promoter for the operon a mutation in the gene for beta-galactosidase

a mutation that disables the repressor

Fluorescent in situ hybridization (FISH) can be used to determine __________. Hints the phylogenetic diversity of an environmental sample how many Salmonella typhimurium cells are present in a sample of unpasteurized apple juice whether a specific piece of mRNA is being produced all of the listed conditions

all of the listed conditions

An organism that cannot synthesize methionine is an example of __________. Hints an auxotroph a prototroph an autotroph a mutant

an auxotroph

Microbial mats differ from biofilms in that they __________. Hints are currently found only in extreme habitats are found only attached to surfaces contain more than one species of microorganism in the community have different environmental conditions at various depths within the community

are currently found only in extreme habitats

Denitrification contributes to global warming by __________. Hints destroying ozone decreasing the amount of organic nitrogen in the soil increasing soil pH increasing the amount of carbon dioxide released

destroying ozone

By isolating total community RNA, using reverse transcriptase to make cDNA copies of it, and then sequencing the cDNA, ecologists can __________. Hints determine the community genome expression at the moment of sampling determine the community genomic potential at the moment of sampling determine the community genome translation at the moment of sampling determine the community metabolic activity at the moment of sampling

determine the community genome expression at the moment of sampling

Phylogenetic analysis of microbial communities in nature using various PCR techniques has revealed that only a minority of phylotypes have been cultured from the environment and the most common phylotypes have not been grown in in the laboratory. This is due in part to __________. Hints lack of sufficient sampling of the community enrichment bias poor technique the uncultured organisms' being rare in the community

enrichment bias

A change in allele frequencies in a set of organisms over time is called __________. Hints fitness mutation selection evolution

evolution

In anoxic environments, organic compounds are cycled back to carbon dioxide and methane by __________. Hints metabolism glycolysis cellular respiration fermentation

fermentation

Comparing the different generations of DNA sequencing, which would be most appropriate for a 10 Mbp piece of DNA that could not be fragmented? Hints second generation third generation fourth generation first generation

fourth generation

Metagenomics is a more sensitive analysis of community diversity than rRNA-based analyses because __________. Hints rRNA genes are not found in all of the organisms present in the environment the extraction of the DNA from the environmental samples is more efficient more clone libraries can be assembled genes do not have to be amplified by PCR before being sequenced

genes do not have to be amplified by PCR before being sequenced

Giardia is a type of protist that is remarkably similar to bacteria in that it __________. Hints does not contain a mitochondrion is anaerobic is unicellular has all of the listed characteristics

has all of the listed characteristics

Mutagens decrease the likelihood of mutations in DNA. increase the likelihood of mutations in DNA. are the sole cause of mutations in DNA. come in two basic forms: ionizing and nonionizing radiation.

increase the likelihood of mutations in DNA.

If a researcher wanted to compare the enzymatic capacity to degrade compounds in a water column at various depths under a specific set of conditions, which would be the most useful approach? Hints metaproteomics metagenomics metabolomics genomics

metaproteomics

Carbon dioxide and methane are potent greenhouse gases, with methane having 20 times more warming potential in the atmosphere than CO2. As global warming progresses, there is the real possibility that increased temperatures on land and in the oceans will lead to a positive feedback effect leading to accelerated warming. From the carbon reservoirs listed below with their percentage of the total carbon on Earth, what would be the most dangerous potential source of C that could be released to potentiate further warming? Hints rocks and sediments (99.5%) fossil fuels (0.006%) methane hydrates (0.014%) oceans and terrestrial biosphere (0.053%)

methane hydrates (0.014%)

The evolution of plants that grow on dry land is thought to have depended in part on their development of symbiotic associations with which group of microorganisms? Hints Agrobacterium lichens rhizobia mycorrhizae

mycorrhizae

A method of genetic fingerprinting that relies on the location of small subunit rRNA genes on DNA fragments is called __________. Hints repetitive extragenic palindromic PCR amplified fragment length polymorphism restriction fragment length polymorphism ribotyping

ribotyping

Metagenomics involves the analysis of a microbial community by __________. Hints generating a complete sequence of the genomes of all of the organisms in an environment sampling and sequencing all of the genes in an environment generating a phylogenetic tree based on all of the versions of a gene in an environment sequencing all of the community RNA in an environment

sampling and sequencing all of the genes in an environment

Mice that are injected with only the R strain of Streptococcus pneumoniae 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.

stay healthy, because their immune systems can kill this strain easily.

What component(s) make up the structure of a virion? Hints capsid and genome genome and envelope capsid, genome, envelope capsid

capsid and genome

Which of the following populations would be most likely to demonstrate genetic drift? Hints A researcher transfers bacteria into fresh medium but accidentally collects only a very small quantity of bacteria in the process. A large population of bacteria is grown over an extended period in a continuous culture system. Someone takes an extended course of antibiotics, leaving a relatively small number of surviving bacteria. 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.

A researcher transfers bacteria into fresh medium but accidentally collects only a very small quantity of bacteria in the process.

Why does conjugation between an Hfr strain and an F- strain not result in two Hfr strains? The transferred genes typically recombine with the recipient chromosome. The cell membranes between the two strands never fuse together. Conjugation is typically disrupted before the fertility factor can be transferred. Hfr strains lack fertility factor.

Conjugation is typically disrupted before the fertility factor can be transferred.

What benefit does the F- strain receive from mating with an Hfr strain? It can now produce sex pili. It picks up a fertility factor. It becomes an F+ cell. It acquires new, potentially beneficial genes from the Hfr strain.

It acquires new, potentially beneficial genes from the Hfr strain.

According to the animation, how do the repressor proteins block the transcription of the structural genes? It binds to the promoter when deactivated. It binds to the repressor when deactivated. It binds to the operator when activated. It binds to the repressor gene when activated. It binds to the promoter when activated. It binds to the repressor gene when deactivated.

It binds to the operator when activated.

Why does the structure of plant and bacterial cells illustrate the reason for having few enveloped viruses that infect these cells? Hints Plant and bacterial cells contain cell walls that prevent viral infection. 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.

Plant and bacterial cells contain cell walls that limit the virus from budding out and obtaining the envelope.

When the cell is NOT in the presence of tryptophan, RNA polymerase can transcribe mRNA. the repressor proteins bind to the operator. the repressor proteins are active. structural genes are not transcribed.

RNA polymerase can transcribe mRNA.

If you wanted to culture a methanogen, what would be one of the steps you would have to take? Hints Removing all O2 from the headspace of the culture. Removing all CO2 from the headspace of the culture. Removing all H2 from the headspace of the culture. Filling the headspace of the culture with N2.

Removing all O2 from the headspace of the culture.

Which operons are always transcribed unless deactivated? Inducible operons Repressible operons Inducible and repressible operons

Repressible operons

A fungus that is coenocytic, is involved in food spoilage, and produces asexual spores in a sac could be __________. Hints a mushroom glomeromycetes Penicillium Rhizopus

Rhizopus

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 cells picked up the capsules from the S 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 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.

Researchers discover a new species of bacterium that has an unusual metabolism. However, it has biochemical and morphological similarities to other species. What is the most comprehensive and effective approach to determine how to classify these bacteria? Hints The bacteria should be classified with the other bacteria that use the most similar biochemical pathways. Because of their unusual metabolic pathways, the bacteria should be classified in a new group. The bacteria should be classified with other bacteria that have the most similar morphology. The bacteria should be classified by using genomic analyses to construct phylogenies.

The bacteria should be classified by using genomic analyses to construct phylogenies.

What characteristic of the S strain allows it to evade the immune system of the mice? The cells have a capsule. They are naturally competent. They are genetically engineered to be resistant to killing. They are resistant to heat.

The cells have a capsule

What must occur for bacterial conjugation to take place? Each cell must contain a plasmid. The cells must come into contact with each other. One of the cells must be E. coli. The cells must transfer RNA.

The cells must come into contact with each other.

What would be the most likely effect of a mutation in the operator of a lac operon? Hints The genes would be constitutively expressed. beta-galactosidase would not be produced. Regulation would occur normally. The repressor would not be produced.

The genes would be constitutively expressed.

What happens to the packaged DNA of a specialized transduced phage when it infects a new recipient cell? The host DNA integrates, with the prophage, into the new recipient chromosome. The DNA is chewed up by enzymes found in the recipient cell. The DNA begins to replicate without integrating into the host chromosome.

The host DNA integrates, with the prophage, into the new recipient chromosome.

According to the animation, where on the DNA strand does a repressor bind? The operator The inducer The promoter The structural genes

The operator

With which genetic region does the repressor protein interact? lacZ lacY The operator region The regulatory gene The promoter region

The operator region

How is the pan genome differentiated for a given species? Hints The pan genome contains only the metabolic information for a given species. The pan genome only contains toxin-producing genes. The pan genome is the genomic information shared by all members of a given species. The pan genome is in addition to the core genome and only found in some members of a given species.

The pan genome is in addition to the core genome and only found in some members of a given species.

According to the animation, to what genetic element does the RNA polymerase bind? The repressor protein The repressor mRNA The operator The promoter

The promoter

If the biochemical oxygen demand (BOD) of a lake is very high, how will that affect the aquatic life in the lake? Hints The BOD does not have an impact on available oxygen in the lake. There will be less oxygen available for the aquatic life due to the microbial activity. There will be more oxygen available for the aquatic life but much less oxygen available to the microbial populations. There will be more oxygen available for the aquatic life due to the microbial activity.

There will be less oxygen available for the aquatic life due to the microbial activity.

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? Hints They differ in their phenotype but not in their genotype. They differ in their genotype and in their phenotype. They differ in their genotype but not in their phenotype. They don't differ in genotype or phenotype.

They differ in their genotype and in their phenotype.

Which of the following is true of mitochondria? Hints They absorb photons in order to convert light energy to chemical energy. Mitochondria are not affected by antibacterial antibiotics. In the mitochondrial inner membrane, energy is produced through fermentation. They have their own DNA, mtDNA, which encodes some very important mitochondrial proteins.

They have their own DNA, mtDNA, which encodes some very important mitochondrial proteins.

What is the basic function of the lac operon? To code for enzymes involved in catabolizing lactose. To produce lactose when none is present To code for enzymes involved in synthesizing lactose. To produce glucose when none is available

To code for enzymes involved in catabolizing lactose.

While most of the oil spilled into the Gulf of Mexico from the Deepwater Horizon drilling rig in 2010 has disappeared, some of the oil spilled from the Exxon Valdez oil tanker into Prince William Sound, Alaska, in 1989 still remains in the coastal sand and sediments. What possible differences in these two spills could account for the different rates of petroleum degradation? Hints the amount of oil spilled and the seawater salts composition the types of bacteria present and the amount of oxygen in the water ambient temperatures and the types of hydrocarbons present seawater salt composition and types of bacteria

ambient temperatures and the types of hydrocarbons present

Competent cells are cells that have the ability to produce capsules. can take up DNA from their surrounding environment and integrate it into their own chromosomes by recombination. are killed by heat. are also considered "rough-strain" based on colony phenotype.

can take up DNA from their surrounding environment and integrate it into their own chromosomes by recombination.

For organisms to be considered members of the same species, they must __________. Hints have similar but not distinct traits be genetically and phenotypically cohesive share an ancestor at any point in their evolution be phenotypically identical

be genetically and phenotypically cohesive

All of the following are true of biofilms EXCEPT that __________. Hints biofilms protect organisms from antibiotics biofilm formation and dispersal are regulated processes biofilms are composed of only one species at a time biofilms form on virtually all submerged surfaces in nature

biofilms are composed of only one species at a time

A nucleotide-altering chemical can cause double-stranded breaks in the DNA. can alter nitrogenous bases of DNA, resulting in incorrect base pairing. can be incorporated into the DNA, to cause a mispairing of bases. can slip in between stacked bases, causing bulges in the DNA structure.

can alter nitrogenous bases of DNA, resulting in incorrect base pairing.

The strategy for bioremediation of large sites contaminated by inorganic pollutants like toxic metals and radionuclides is usually to __________. Hints contain the pollutants by converting them into a less mobile form break down the pollutants to less harmful products completely remove the contaminants from the site completely oxidize the pollutants to carbon dioxide and water

contain the pollutants by converting them into a less mobile form

A transducing phage has a viral coat made of host proteins. cannot infect new host cells. is a lysogenic bacteriophage. contains fragments of the host chromosome instead of the viral genome.

contains fragments of the host chromosome instead of the viral genome.

What has occurred when organisms share a trait that was NOT inherited from a common ancestor? Hints parallel evolution divergent evolution perpendicular evolution convergent evolution

convergent evolution

Given the extremely low concentrations of nutrients in the open ocean, most marine Bacteria typically need all of the following adaptations EXCEPT __________. Hints proteorhodopsins many periplasmic binding proteins large cell size high surface area-to-volume ratios

large cell size

Based on comparative studies of agricultural soils or polluted soils compared with undisturbed soils, disturbance of soil microbial communities tends to lead to __________. Hints no change in microbial community composition greater microbial metabolic activity lower prokaryotic diversity higher microbial abundance

lower prokaryotic diversity

The role of the iron-containing leghemoglobin in the rhizobial root nodules of soybeans is to __________. Hints carry O2 from the leaves to the root nodule carry iron to the rhizobial bacteria lower the amount of free O2 in the root nodule carry O2 from the root nodule to the leaves

lower the amount of free O2 in the root nodule

Thymine dimers result from mistakes by DNA polymerase. nonionizing radiation. ionizing radiation. nucleoside analogs.

nonionizing radiation

Oxygen depleted zones at varying depths in marine waters between 100-1000m are called __________. Hints oxygen minimum zones dead zones photic zone pelagic zones

oxygen minimum zones

Microarrays that have been designed to screen samples for specific groups of bacteria are called __________. Hints microchips phylochips biochips phytochips

phylochips

Genes that retain their function yet change over evolutionary time as organisms diverge are called orthologs. Organisms with identical or very similar orthologous genes belong to the same __________. Hints phenotype ribotype phylotype genotype

phylotype

Which of the following is NOT included in the genome? Hints noncoding regions of DNA proteins genes that encode RNAs coding regions of DNA

proteins

Gene duplication is thought to have had a significant influence on the evolution of microbes because __________. the duplicated gene can be mutated, possibly leading to a useful new gene function or product, while the original copy can still perform its original (and possibly essential) genetic function the duplicated gene can allow for increased transcription and synthesis of the gene product the duplicated gene can serve as a "back-up" copy the duplicated gene can be given away to another organism by conjugation

the duplicated gene can be mutated, possibly leading to a useful new gene function or product, while the original copy can still perform its original (and possibly essential) genetic function

When the cell is not in the presence of lactose, the repressor proteins are inactivated. the repressor proteins bind to the operator. transcription of the structural genes occurs. no transcription of the regulatory genes occurs.

the repressor proteins bind to the operator.

The rhizosphere is __________. Hints the top inch of soil that contains a large number of microorganisms the soil immediately surrounding the root of a plant the surface of the roots of a plant all of the microorganisms living in soil

the soil immediately surrounding the root of a plant

Traditional classification of fungi by sexual spore type has been __________. Hints modified due to phylogenetic analysis completely discarded by phylogenetic analysis proven incorrect by phylogenetic analysis upheld by phylogenetic analysis

upheld by phylogenetic analysis

How does specialized transduction differ from regular lysogeny? The resulting bacteriophage from specialized transduction cannot infect a new host cell. The resulting bacteriophage from specialized transduction does not contain any viral DNA. The prophage is not excised during specialized transduction. The prophage in specialized transduction carries with it pieces of the host chromosomal DNA.

The prophage in specialized transduction carries with it pieces of the host chromosomal DNA.

What is the overall function of the trp operon? To ensure that the cell has a supply of tryptophan at all times To control the production of repressor proteins To block RNA polymerase from the structural genes To always make sure the operator is being bound to repressor proteins

To ensure that the cell has a supply of tryptophan at all times

What is unique about transduction compared to normal bacteriophage infection? The bacteriophage does not erupt from an infected cell during transduction. The bacteriophage takes fragments of the cell with it during transduction. Transduction transfers DNA from the chromosome of one cell to another.

Transduction transfers DNA from the chromosome of one cell to another.

Initiation of biofilm formation in many organisms is at least in part regulated by c-di-GMP, which alters gene expression and enzyme activity leading to all of the following EXCEPT __________. Hints initiation of flagella formation production of intercellular signaling molecules formation of cell surface attachment proteins initiation of extracellular polysaccharide production

initiation of flagella formation

A farmer finds that his soybean plants do not look healthy. They appear stunted and the leaves are a yellowish color, indicating possible lack of nitrogen. To have a more successful crop next year, he should consider__________. Hints fertilizing with ammonia fertilizer inoculating his fields with the appropriate cross-inoculation group of rhizobia fertilizing his fields with iron. increasing irrigation of his fields.

inoculating his fields with the appropriate cross-inoculation

The phylogenetic diversity analysis of complex microbial communities often targets small subunit (SSU) ribosomal RNA genes. This is because rRNA is found in all organisms and __________. Hints is easier to extract from samples has more genes than mRNA is made by cells only at certain times is highly conserved over evolutionary time

is highly conserved over evolutionary time

Both ammonium (NH4+) and nitrate (NO3-) are assimilated by primary producers, but ammonium is the preferred form of nitrogen for fertilizers used in agriculture because __________. Hints nitrate leaches out of soils easily due to its negative charge ammonium does not cause eutrophication (algal blooms) if it enters aquatic ecosystems ammonium leaches out of soils easily due to its positive charge ammonium is converted to nitrate by microbial nitrification

nitrate leaches out of soils easily due to its negative charge

Sequencing an organism's genome often leads to identification of hypothetical proteins, which are characterized as __________. Hints proteins that are overexpressed proteins that are expressed proteins that likely exist though their function is unknown proteins that likely exist with known functions

proteins that likely exist though their function is unknown

As a microbiologist, you have been asked to advise a town council on the possible ways to remove PCB contaminants from the local groundwater. Which microbial process is most likely to have bioremediation potential in this case? Hints aerobic dechlorination containment and stabilization leaching reductive dechlorination

reductive dechlorination

Data that support the endosymbiotic theory include __________. Hints that all eukaryotes have mitochondria that all photosynthetic organisms contain chloroplasts that mitochondria and chloroplasts have 80S ribosomes that the nucleus contains genes that came from bacteria

that the nucleus contains genes that came from bacteria

Industrial production of nitrogenous fertilizers from N2 now equals or exceeds the amount of nitrogen fixation carried out by microbes in the biosphere. The resulting increase in primary production is an example of the fact that __________. Hints N is generally not a limiting nutrient for primary production there is a fixed quantity of N on Earth the C and N cycles are closely coupled synthetic fertilizers work better than natural N sources for primary production

the C and N cycles are closely coupled

Compared with pure cultures grown in the lab, microbes in nature usually experience a wider range of environmental conditions, more variation in conditions over time, and more contact with other organisms. Therefore, the same organism in nature will __________. Hints typically grow slower than in pure culture typically grow only on surfaces typically grow faster than in pure culture carry out completely different metabolisms than in pure culture

typically grow slower than in pure culture

Bacterial conjugation is often referred to as bacterial sex. Why is this term inaccurate? Conjugation does not result in the formation of new offspring. Bacteria are neither male nor female. It does not require two cells to occur. Sex is a phenomenon only seen in animals.

Conjugation does not result in the formation of new offspring.

Which statement about conjugation is false? Conjugation is a process of bacterial reproduction. After conjugation, each cell involved has a copy of the shared DNA. E. coli is the model for bacterial conjugation.

Conjugation is a process of bacterial reproduction.

How does an F+ cell differ from an Hfr cell? Hfr cells cannot perform conjugation. F+ cells have no plasmids. Hfr strains can no longer reproduce. Hfr strains have the F plasmid integrated into the chromosome.

Hfr strains have the F plasmid integrated into the chromosome.

Halobacteria tend to have fewer hydrophobic amino acids in their proteins than other bacteria. Why? Hints There is less water in a highly saline environment. Proteins "salt out" of solution in a very lipid-rich environment. The salt ions add to the hydrophobic proteins and make them hydrophilic. In a highly saline environment, hydrophobic proteins have an increased likelihood of precipitating out of solution.

In a highly saline environment, hydrophobic proteins have an increased likelihood of precipitating out of solution.

Which of the following describes how 5-bromouracil might create a mutation? It causes double-stranded breaks of the DNA. It creates bulges in the DNA that must be repaired. It can replace the base thymine, and can base pair with guanine rather than adenine. It can form thymine dimers.

It can replace the base thymine, and can base pair with guanine rather than adenine.

A small farm pond containing many species of microorganisms (bacteria, cyanobacteria, algae, and protozoa) was perturbed when runoff from a manure pile entered the pond. The added nutrients soon turned the water green due to a bloom of cyanobacteria. How did this affect the microbial community in the pond? Hints Species richness increased and species abundance increased. Species richness increased and species abundance decreased. Species richness decreased and species abundance decreased. Species richness decreased and species abundance increased.

Species richness decreased and species abundance increased

Phylogenetic trees for bacteria are constructed by which of the following? Hints 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 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

Many nutrient cycles are coupled and changes in one cycle will affect another. This means that a change in the amount of carbon dioxide fixed is intimately affected by the amount of __________. Hints hydrogen available in an ecosystem nitrogen available in an ecosystem methane available in an ecosystem oxygen available in an ecosystem

nitrogen available in an ecosystem

When a transducing phage interacts with a new host cell, it will cause the new cell to produce more transducing phage. the DNA from the previous host can recombine with the new host chromosome. the new host cell will be lysed.

the DNA from the previous host can recombine with the new host chromosome.

Frameshift mutations can be very severe. What is one reason why they are often so serious? Hints 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 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 changes in many bases downstream and can affect many of the amino acids in the protein.

Compounds that are NOT produced by organisms anywhere in nature are called __________. Hints foreign abiotic xenobiotic xerobiotic

xenobiotic