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Which of the following statements is TRUE?
A) Lambda is a temperate phage that infects Escherichia coli.
B) Lambda is a linear double-stranded DNA phage.
C) Lambda is replicated by the rolling circle mechanism.
D) Lambda is a temperate phage that replicates its double-stranded DNA genome with a
rolling circle mechanism.
Compared to Eukaryotes, Bacteria and Archaea have ________ surface-to-volume
ratios, causing ________ nutrient exchange and growth rates.
A) lower / lower
B) lower / higher
C) higher / lower
D) higher / higher
The process in which related DNA sequences from two different sources are exchanged
is called
A) transduction.
B) phage conversion.
C) reversion.
D) homologous recombination.
Which of the following pairs of microorganisms are NOT likely to form close
associations or consortia?
A) purple sulfur bacteria and dissimilative sulfur-reducers
B) dissimilative sulfur-reducers and dissimilative sulfur-oxidizers
C) nitrogen-fixing cyanobacteria and fungi
D) nitrogen-fixing cyanobacteria and dissimilative sulfate-reducers
In E. coli, the adenine in the sequence GATC is methylated by the Dam enzyme. In the
same cells a restriction endonuclease recognizes and cleaves dsDNA with GATC on
either strand. Why does E. coli have these two enzymes?
A) The enzymes cut the E. coli genome into pieces that bind to viral particles and
inhibit viral replication.
B) The enzymes increase the rate of mutation and genome rearrangement, thus
increasing the likelihood that E. coli cells will mutate and become resistant to viral
infection.
C) The enzymes encourage lysogeny because the cleavage sites are recognized by viral
integrases.
D) The enzymes protect E. coli from infection by preferentially degrading viral or other
exogenous DNA that is not methylated.
The phylogenetic trees of the nifH and SSU rRNA genes are incongruent because
A) nitrogenase is an anaerobic enzyme.
B) nitrogenase evolves rapidly.
C) of horizontal gene transfer.
D) very few microbes have the nifH gene.
A population of metabolically related microorganisms is called a(n)
A) guild.
B) niche.
C) ecosystem.
D) haplotype.
Cytolytic toxins
A) are extracellular proteins.
B) cause cell lysis and death.
C) damage host cytoplasmic membrane.
D) are extracellular proteins that cause cell lysis and death by damaging the host
cytoplasmic membrane.
A triplet of bases on an mRNA molecule is known as a(n)
A) amino acid.
B) anticodon.
C) codon.
D) ribosome-binding sequence.
The early energy reactions used hydrogen, which is a powerful ________ and could
have been used to form ________.
A) oxidant / the proton motive force
B) electron donor / the proton motive force
C) electron acceptor / oxygen
D) oxidant / oxygen
The precursor of each new nucleotide in a strand of DNA is a
A) deoxynucleoside 5'-diphosphate.
B) deoxynucleoside 3'-diphosphate.
C) deoxynucleoside 5'-triphosphate.
D) deoxynucleoside 3'-triphosphate.
A chemoorganotroph growing optimally at 55C and pH 2 in complex media would most
likely be a member of the genus
A) Methanocaldococcus.
B) Halobacterium.
C) Methanococcus.
D) Thermoplasma.
The transfer of antibodies through the placenta from mother to fetus is an example of
A) natural passive immunity.
B) innate immunity.
C) natural active immunity.
D) artificial active immunity.
Of the phage listed below, which creates mutations in its host genome via transposition?
A) lambda
B) M13
C) Mu
D) T7
A protein region with a specific function and structure is called a
A) conserved site.
B) domain.
C) locale.
D) motif.
Almost all plasmids are double-stranded DNA.
Unusually shaped viruses, such as lemon-shaped and spindle-shaped, have recently
been discovered in
A) Archaea.
B) Bacteria.
C) Archaea and Bacteria.
D) Eukarya.
Bacterial mating (or conjugation) is a bidirectional process where nucleic acids (DNA
or RNA) are transferred between two cells.
Relative to enzymes in mesophilic microorganisms, which of the following is NOT
characteristic of enzymes in psychrophiles?
A) decreased alpha helices
B) decreased beta sheets
C) less hydrogen bonds
D) less ionic bonds
Which metric describes the proportion of EACH species present in a community?
A) species abundance
B) species diversity
C) species evenness
D) species richness
Simple staining and microscopy could easily distinguish the different taxa intermixed
within a community of Sarcina, Staphylococcus, and coryneform bacteria.
Increasing atmospheric carbon dioxide is
A) increasing sedimentation of C, Ca, and Si.
B) increasing the effect of the biological pump.
C) fueling increased primary production in ocean waters.
D) acidifying the ocean and decreasing the rate of formation of calcareous shells.
Which statement exemplifies the biological pump concept?
A) Autotrophs bring in light photons to synthesize ATP.
B) Bacteria oxidize Fe2+ into Fe3+, and Archaea reduce Fe3+ back into Fe2+.
C) Calcium ions are brought into cells while toxic physiological byproducts are
released.
D) Primary producers sink to the deep ocean, which provides deep ocean organisms
with nutrients when the primary producers die.
What is a/are potential reservoir(s) for viruses?
A) water
B) insects
C) bats
D) fomites
Which of the following roles do B cells play?
A) antigen presentation
B) antigen processing
C) antigen uptake
D) antigen presentation, processing, and uptake
In contrast to bacterial endospores, fungal spores LACK ________ resistance.
A) chemical
B) desiccation
C) heat
D) freezing
Trypanosoma and Leshmania species are transmitted by
A) direct person-to-person contact.
B) insect vectors.
C) contaminated food or water.
D) contaminated needles and syringes.
Each of the V domains in immunoglobulins has ________
complementarity-determining regions.
A) one
B) two
C) three
D) four
Which of the following mechanisms leads to INCREASED transcriptional activity?
A) An sRNA binds to the ribosome binding site.
B) Ribonuclease activity is blocked by sRNA complementary binding to the end of a
transcript.
C) The ribosome binding site is made available from sRNA binding to part of it.
D) Recruitment of RNA polymerase is enhanced when sRNA binds to and removes a
repressor.
In a stratified lake, the warmer and less dense layer is called the
A) epilimnion.
B) hypolimnion.
C) hyperlimnion.
D) thermocline.
Proteomic analysis of a microbial community indicated an abundance of
phycobiliproteins. Which phototrophic group is likely active and abundant in this
community?
A) cyanobacteria
B) eukaryotic phototrophs
C) green bacteria
D) prochlorophytes
A gram-negative, nonsporulating rod that is highly motile, oxidase negative,
facultatively aerobic, ferments glucose, and urease-positive is likely to be of which
genus?
A) Pseudomonas
B) Proteus
C) Lactobacillus
D) Rickettsia
Nitrate (NO3-) reduced into ammonia (NH3) to produce energy for the cell is called
A) ammonification.
B) dissimilative reduction of nitrate to ammonia (DRNA).
C) nitrification.
D) redox.
Which of the following is NOT a function of the human gut microbiome?
A) production of essential amino acids and vitamins
B) production of volatile fatty acids from polysaccharides
C) iron and trace metal absorption
D) maturation of the gastrointestinal tract
