Test 3 practice questions

Which of the following is true of the term "wild type"? A. It can apply to individual genes or entire organisms B. It describes a strain that does not undergo horizontal gene transfer C. It describes a group of genetically identical organisms D. It refers to a type of mutant phenotype

A

Which of the following was likely the host cell during primary endosymbiosis? A. An archaeon B. An H2-producing bacterium C. An H2-using bacterium D. A photosynthetic bacterium

A

Metagenomic studies have revealed many nonextremophile Archaeans. What would be needed to develop good experimental gene transfer systems for these species? (select all that apply) A. New culturing techniques B. New selectable markers or auxotrophic strains C. Evidence that transformation is possible in archaeans D. Evidence of F plasmid genes

A and B

If DNA enters a bacterial cell through transformation, it can ____________. (Choose all correct answers) A. Replicate independently with or without an origin of replication B. Replicate independently if it has an origin of replication C. Be degraded by the recipient cell D. Undergo recombination with the recipient cell chromosome

B, C, and D

Which statements are examples of evidence of the endosymbiotic theory? (select all that apply) A. Mitochondria and chloroplasts have peptidoglycan cell walls B. Mitochondria and chloroplasts replicate themselves within eukaryotic cells C. Certain antibiotics inhibit both bacterial ribosomes and ribosomes in mitochondria and chloroplasts D. Mitochondria and chloroplasts have 16S RNA sequences characteristic of bacteria

B, C, and D

To subculture bacteria that lack the ability to synthesize a particular amino acid, a researcher could ____________________. A. Use replica plating and then take a sample from a colony that grew on both the master plate and the new plate B. Take a sample of bacteria from a test tube that contained supplemented medium and varied strains C. Use replica plating and the take a sample from a colony on the master plate that did no appear on the newly made plate D. Take a sample of a bacteria from a test tube that contained supplemented medium and a single strain

C

What is the most important way that gene duplication allows for the development of new gene functions? A. Gene duplication splits one gene into two, producing two copies of its product B. Gene duplication produces a new double gene that works entirely differently from the original gene C. Gene duplication provides a spare copy of gene that is free to vary without interfering with the production of the original gene product D. Gene duplication describes the appearance of the same gene in two different species

C

When a bacterial or archaeal cell is infected by a virus for the first time ______________________. A. It can use restriction enzymes for defense but not phage exclusion B. It can use CRISPR even if it has never encountered a similar virus before C. It may still be able to use CRISPR due to prior exposure to pieces of DNA from that virus that it encountered in the environment D. It can use only nonspecific defenses such as restriction enzymes, phage exclusion, and programmed cell death.

C

When the recipient's gene is replaced by a donor's gene through recombination, the process is called ________________. A. Transposition B. Gene deletion C. Gene conversion D. Gene duplication

C

Which of the following is true of the symbiogenesis hypothesis? A. The eukaryotic ancestor took up a single ancestral prokaryote that diverged into mitochondria and chloroplasts B. The eukaryotic ancestor took up a single ancestral archaeal cell that contained the ancestor of chloroplasts C. The eukaryotic ancestor developed a nucleus after taking up the ancestor of mitochondria D. The eukaryotic ancestor had a nucleus before the ancestor of mitochondria took up residence

C

Which process listed below allows genetic material to be transferred from a virus-like particle that lacks genes for its own replication A. Transduction by a dsDNA phage Mu B. Conjugation of an F+ plasmid C. Gene transfer through a gene transfer agent D. Transformation of a linear piece of DNA

C

Why can bacteria undergo rapid evolutionary change? A. Bacteria pass through numerous bottlenecks B. Bacteria mutate at high rates C. Bacterial populations are large and can reproduce quickly D. Bacteria experience intense selective pressure

C

Why is transposon mutagenesis so useful? A. Fluorescently labeled transposons are used to identify sequences of interest B. Insertion of a transposon into a gene amplifies production of the gene product C. Insertion of a transposon into a gene means that the gene product is no longer made D. Mutated transposons are unable to replicate in a host cell

C

A researcher using multilocus sequence analysis (MLSA) is probably ______________. A. Examining phylogenetic relationships of closely related species B. Trying to identify gene duplications C. Trying to Classify SSU rRNA subunits D. Estimating genome relatedness

A

All homologs are ____________. A. Genes that have descended from a single ancestral gene B. Genes that share a common function C. Genes that have undergone gene duplication D. Genes that are present in a wide variety of organisms

A

BOTH hypotheses on the origins of eukaryotes agree that... A. eukaryotic cells are chimeras with attributes of archaea and bacteria B. the nucleated cell arose after the endosymbiosis event C. the nucleated cell arose before the endosymbiosis event D. the nucleated cell was a direct descendant of a bacterial cell

A

Consider a mutation in which the change is from UAC to UAU. Both codons specify the amino acid tyrosine. Which type of point mutation is this? A. Silent mutation B. Missense mutation C. Frameshift mutation D. Nonsense mutation

A

For phylogenetic studies, which characteristic is NOT a reason why SSU rRNA gene sequences are favored over other nucleotide sequences? A. They are completely conserved B. They are functionally constant C. They make up the largest database of gene sequences D. They are universally distributed

A

If a mutation occurs in the third base of UUU, converting it to UUC, while the amino acid specified remains phenylalanine, then the mutation is ____________. A. Neutral B. Selectable C. Deleterious D. Beneficial

A

If a researcher wanted to know which bacterial cells had taken up a gene of interest in a laboratory study, the fastest and easiest approach would be _____________________. A. To add an antibiotic resistance gene so that only bacteria that took up the gene of interest would be able to grow in a medium containing the antibiotic B. To cause a mutation that would make an organism unable to attach to a substrate C. To cause a mutation that would change the color of the bacterium D. To add a gene for an additional metabolic product that can be produced and accumulate in the medium

A

If you find a region of DNA that has been much higher percentage of G+C base pairs than the rest of the genome then a likely explanation is that _______________. A. Horizontal gene transfer has occurred B. Gene deletion has occurred C. Gene duplication has occurred D. Vertical gene transfer has occurred

A

The first catalytic and self-replication biological molecule was most likely ________. A. RNA B. Proteins C. ATP D. DNA

A

There is evidence that viruses _______________. A. Are very ancient B. Developed the ability to infect cells only once eukaryotes evolved C. Only developed capsids relatively recently D. Must have evolved prior to gene transfer agents

A

True or False: One theory states that the formation of the nuclear membrane was to separate the spliceosome in the nucleus from the ribosomes in the cytoplasm. A. True B. False

A

Very different taxa of succulent plants in the southeastern United States and in Africa have similar appearances. This is an example of _____________. A. Convergent evolution B. Paralogs C. Divergent evolution D. Homology

A

What characteristics make a gene a good candidate for determining the evolutionary relationships between organisms? A. Highly conserved and universally distributed B. Highly conserved C. Universally Distributed D. Transferred Horizontally between species

A

When conjugation occurs between Hfr cell and an F- cell, _______________ A. it is usually interrupted before the entire chromosome is transferred B. The origin of the F plasmid always points in the same direction C. A given strain can transfer genes in any order D. It is not possible for the F- cell to become an Hfr or F+ cell

A

Which hypothesis proposes an explanation for the origin of eukaryotic organelles? A. the endosymbiotic hypothesis B. the hydrogen hypothesis C. the origins hypothesis D. the eukaryotic hypothesis

A

Which of the following is a frameshift mutation? A. The insertion or deletion of one or two bases B. The insertion or deletion of one base but not of two or three bases C. The insertion of one, two, or three bases D. The insertion or deletion of three bases

A

Which of the following is true of a specialized transduction of the galactose operon? A. Most of the viral particles produced from a cell with a prophage will not contain the galactose operon, but a few will, and these can transduce galactose genes B. Most of the viral particles produced from a cell with a prophage will contain the galactose operon, and these can transduce galactose genes C. Specialized transduction of the galactose operon requires that the prophage inserts itself within the operon prior to the production of new phages D. Specialized transduction of the galactose operon requires that the prophage is independent of the bacterial chromosome rather than integrated within it

A

Transposable elements are found in _________________. (select all that apply) A. Bacteria B. Viruses C. Archaeans D. Eukaryl Cells

A, B, C, and D

Bacterial species are characterized by ____________. (select all that apply) A. Being genomically and phenotypically coherent B. Being monophyletic C. Being clearly distinguishable from other species D. Interbreeding to produce fertile offspring

A, B, and C

Which statements are true of conjugation? (Select all that are correct) A. It is a type of horizontal gene transfer B. Genetic material travels through a pilus C. Plasmids or chromosomes can be transferred D. Cells do not require physical contact

A, B, and C

What traits did the last universal common ancestor (LUCA) probably have? (select all that apply) A. Lived in a cold environment B. Anaerobic C. Used hydrogen (H2) as an energy source D. Obtained carbon from organic molecules

B and C

An example of a bacterial genotype is _____________. A. The ability to grow on a minimal medium B. The presence of a hisC gene C. The presence of the HisC protein in the bacterial cytoplasm D. The presence of a weak cell wall

B

Hfr strains of Escherichia coli ___________. A. Do not possess an F factor B. Have an integrated F factor C. Have the F factor as a plasmid D. Transfer the complete F factor to recipient cells at a high frequency

B

If you wanted to insert a gene into a phage for transfer to a bacterial cell through specialized transduction, then ___________________. A. The bacterial cell would need to be competent for the genetic material to be transferred B. You could only insert a relatively small amount of DNA unless you used a helper phage C. The DNA would be inserted randomly into the recipient genome and, therefore, could cause unexpected mutations D. After insertion, the viral DNA would replicate independently of the bacterial host chromosome

B

The lack of an ozone layer meant that the early earth ________________. A. Rapidly produced atmospheric oxygen from chemical reactions B. Received intense ultraviolet radiation from the sun C. Was extremely hospitable to early life forms D. Was very cold due to heat loss

B

There has been considerable concern that chemicals released into the atmosphere are damaging the ozone shield, leading to regulations affecting the use of these chemicals. What would be the effect if the ozone shield were severely degraded or lost? A. Conditions would resemble those present during the time period that most fossils were produced B. Large amounts of ultraviolet radiation would reach the Earth's surface and kill many living organisms C. The amount of oxygen (O2) available for living organisms would greatly increase ozone (O3) broke down D. Cyanobacteria would thrive due to the abundance of oxygen

B

True or False: EACH member of a bacterial species contains the pan genome A. True B. False

B

True or False: Eukarya are much more closely related to Bacteria than to Archaea A. True B. False

B

What would happen if you attempted to transform a bacterium that had defective competence-specific protein to bind to the newly entered single-stranded DNA? A. Recombination would be more likely to occur because the DNA would be degraded into smaller pieces by nucleases B. Recombination would be unlikely to occur because DNA would probably be degraded by nucleases C. RecA would bind in place of the competence-specific single-stranded DNA-binding protein D. Recombination would be more likely to occur because the strand would be free to interact with the recipient chromosome

B

What would happen if you skipped sequence alignment while trying to construct a phylogeny? A. It would be easier to recognize gene duplications B. It would be difficult or impossible to determine positional homology C. It would still be possible to determine homology without difficulty as long as a computer was used D. The genes would not be marked with information about their function

B

Which statement(s) is(are) true of archaeal gene transfer? (Select all that apply) A. Gene transfer in conjugation is bidirectional B. More than one type of conjugation has been discovered C. Transduction does not occur D. Transduction is common

B

You discover a parasitic bacterium with a tiny genome. Most likely, this tiny genome developed through __________. A. Ortholog replacement B. Deletion C. Recombination D. Gene duplication

B

What finding(s) would support the RNA world hypothesis for viral origins over the selfish DNA hypothesis? (select all that apply) A. Evidence that the earliest viruses had capsids B. Evidence that viruses existed before gene transfer agents C. Evidence that the earliest viruses had RNA genomes D. Evidence that viruses could have RNA or DNA genomes

B and C

A key concept in evolution is that all mutations are __________. A. Neutral B. Either deleterious or beneficial C. Random D. Deleterious

C

A mutant that has a nutritional requirement for growth is an example of a(n) _____________ A. Organotroph B. Autotroph C. Auxotroph D. Heterotroph

C

A mutation that changes a codon for an amino acid into a stop codon is most precisely described as a __________________. A. Missense Codon B. Induced mutation C. Nonsense codon D. Point mutation

C

A small number of cells is transferred from one host to another. On analysis immediately after transfer, they are found to have a particular trait much more often than the original population. The most likely explanation for this is _____________. A. Artificial selection B. Natural selection C. Genetic drift D. Neutral alleles

C

An important difference between insertion sequences and transposable elements is that ______________. A. Only transposons have inverted repeats B. Insertion sequences are circular C. Insertion sequences are shorter D. Only transposons have a gene for transposase

C

If a researcher needed to generate thymine dimers, the most effective approach would be _________________. A. To expose the DNA to ionizing radiation B. To expose the DNA to a chemical mutagen C. To expose DNA to ultraviolet light D. To wait for natural errors in DNA replication

C

If you wanted to determine the phylogeny of a bacterial group, it would be most important to sequence the ___________. A. mtDNA B. Chromosomal islands C. SSU rRNA genes D. mRNA

C

Mitochondria and Eukarya originated from A. Archaea B. Cyanobacteria C. Proteobacteria D. Purple Bacteria

C

Once several different but related sequences are obtained, which step must be performed BEFORE a phylogenetic tree is constructed? A. Cladistics B. Parsimony C. Sequence allignment D. Threshold Scoring

C

Silent Mutations are common because __________. A. Most mutations occur at the first position of a codon B. Unlike other mutations, they occur naturally C. The genetic code is degerate D. Most mutations occur at the third position of a codon

C

A molecular clock estimate would be inaccurate if ___________________. A. Most mutations were neutral B. Mutations were relatively rare and infrequent C. Most mutations were random D. Mutations were more often deleterious than neutral

D

An advantage of DNA over RNA as the primary repository of genetic information is that DNA ____________. A. Can bind amino acids B. Can catalyze biochemical reactions C. Can catalyze protein synthesis D. Is more stable

D

Banded iron formations are evidence that ____________. A. The earth was anoxygenic when they were produced B. Life had not yet evolved C. Iron oxides are highly soluble D. Large amounts of oxygen were being produced

D

Escherichia Coli can be easily used in transformation experiments in the lab because it ________________. A. Can be made competent through exposure to chitin as long as other environmental conditions are favorable B. Is capable of quorum sensing and, therefore, becomes competent when present in high densities C. Is naturally competent in a wide range of environments D. Can be made competent through exposure to high concentrations of calcium and cold temperatures

D

F' plasmids transfer all of the chromosomal genes that they contain at high frequency because _________________. A. Large numbers of host chromosomal genes can be transferred B. They can produce merodiploids C. They are capable of specialized transduction D. They are small and the entire plasmid is usually transferred

D

For which purpose is it MOST appropriate to use universal 16S rRNA primers? A. To calculate the sequence length B. To determine if an unknown isolate is of a particular species (or taxon) C. To sequence 16S rRNA from all prokaryotes in a sample D. All of the above

D

How would a transposon be affected if the inverted repeat at one end of a transposon was deleted? A. Transposase would cut normally, but the excised DNA would then be degraded. B. Transposase would recognize where to cut on each side, but it would be unable to ligate the cut ends. C. Transposase would function normally D. Transposase would not recognize where to cut on the side with the missing inverted repeat

D

In the Escherichia coli LTEE, one strain rapidly increased it population size by evolving the ability to use citrate as a carbon source. If citrate had not been present, then __________. A. The mutation allowing bacteria to use citrate would have occurred more rapidly B. The mutation allowing the bacteria to use citrate would not have occurred C. The mutation allowing bacteria to use citrate would still have increased their fitness D. There would have been no selective advantage to having the mutation that allowed bacteria to use citrate

D

Most mobile DNA consists of A. Introns B. Plasmids C. Linear chromosomes D. Transposable elements

D

Transposition is a(n) ________________. A. General recombination event B. Analogous recombination event C. Homologous recombination event D. Site-specific recombination event

D

Viruses that have coexisted with a particular bacterial species for a long time _______________. A. May have their own spacers B. May be defenseless against CRISPR C. May incorporate PAM into its genome as a defense D. May develop mutations of the PAM region

D

What is one reason that a paralog might be very different from its ancestral homolog? A. It is probably highly conserved from the ancestral state B. Paralogs are genes that have not undergone gene duplication C. Paralogs are genes that have accumulated neutral mutations D. It may have evolved to have different functions

D

Which characteristic is true of specialized transduction but not generalized transduction? A. The frequency of transfer of a specific gene is very low B. Bacterial DNA is packaged within a viral capsid C. Temperate phages are nor capable of it D. Phage conversion can result

D

Which of the following elements were MOST likely the electron donors and electron acceptors of early microorganisms> A. NADH/O2 B. NADH/Fumarate C. NO2-/O2 D. H2/S0

D

Which organism would have the highest fitness? A. A salamander that lives for many years without reproducing B. A fist that produces millions of eggs, of which a few survive to become adults C. A deer that has a single fawn D. A frog that lays 100 eggs that are raised in a lab, allowing almost all of the offspring to grow to adulthood

D

____________ occur(s) at a greater frequency than _______________ in microbial genomes A. Recombination/Mutations B. Mutations/Repairs C. Insertions/Deletions D. Deletions/Insertions

D

______________ genes are those that have been inherited by different species from a common ancestor A. Housekeeping B. Xenologous C. Paralogous D. Homologous

D