Cyclic 2,3-diphosphoglycerate (cDPG) is present in molar quantities in the cytoplasm
of many hyperthermophilic methanogens. The function of this compound is to
A) prevent rRNA misfolding.
B) prevent chemical damage to DNA at high temperatures.
C) counteract the effects of high osmotic environments.
D) activate hydrogen gas.
The killing of cells by UV irradiation involves
A) absorption at 260 nm by proteins only.
B) absorption at 260 nm by RNA only.
C) formation of pyrimidine dimers.
D) formation of purine dimers.
Diatoms require silicon due to their
A) Ca2+/Si4+ symporters.
B) DNA replication mechanism.
C) ornate frustules.
D) unique phototrophic physiology.
Phagocytes have general antibody receptors called ________ that bind to any antibody
attached to an antigen.
A) antigens
B) antigen receptors
C) Fc receptors
D) membrane detectors
The dose of an antigen that kills 50% of animals in a test group and is used to estimate
the virulence of a pathogen is known as
A) Antigen dose50.
B) Virulence-50.
C) LD50 (lethal dose50).
D) Death rate-50.
In the oceans, sulfur exists primarily as ________, and in rocks and sediments sulfur
occurs mostly as ________ and ________.
A) hydrogen sulfide (H2S) / gypsum (CaSO4) / elemental sulfur (So)
B) hydrogen sulfide (H2S) / sulfate (SO42-) / elemental sulfur (So)
C) sulfate (SO42-) / gypsum (CaSO4) / pyrite (FeS2)
D) sulfate (SO42-) / sulfide (H2S) / elemental sulfur (So)
Some strains of haloarchaea exhibit
A) anoxic growth at the expense of sugar fermentation.
B) anaerobic respiration.
C) anoxygenic photosynthesis.
D) light-driven ATP synthesis under oxygen-limiting conditions.
Which molecular method allows for the detection of a specific organism within a
diverse microbial community?
A) fluorescent DNA staining using DAPI
B) viability staining
C) enrichment techniques
D) fluorescent in situ hybridization
Consider the following experiment. First, large populations of two mutant strains of
Escherichia coli are mixed, each requiring a different, single amino acid. After plating
them onto a minimal medium, 45 colonies grew. Which of the following may explain
this result?
A) The colonies may be due to back mutation (reversion).
B) The colonies may be due to recombination.
C) Either A or B is possible.
D) Neither A nor B is possible.
A species of insect that lives solely on pine sap was found to contain a bacterial
symbiont. Genome sequencing of both the host and the symbiont revealed that the
symbiont lacked many genes required for energy production, and the host lacked genes
for biosynthesis of several essential amino acids. What is/are the most likely
mechanism(s) that caused the loss of these genes?
A) coevolution
B) horizontal gene transfer
C) increased mutation rate
D) horizontal gene transfer and increased mutation rate
What products would be expected to form during anoxic degradation of the
seven-carbon compound benzoate following reduction and cleavage of the aromatic
ring?
A) 1 three-carbon compound and 1 four-carbon compound
B) 1 three-carbon compound and 2 two-carbon compounds
C) 2 three-carbon compounds and CO2
D) 3 two-carbon compounds and CO2
Which of the following uses its cell wall glycolipids to absorb hydroxyl radicals and
superoxide anions?
A) Staphylococcus aureus
B) Streptococcus pyogenes
C) Mycobacterium tuberculosis
D) Escherichia coli
Which public health measure(s) is/are MOST effective against pathogens transmitted
through common vehicles?
A) water purification
B) mosquito control
C) food safety regulations
D) water purification and food safety regulations
Termination of RNA synthesis is ultimately determined by
A) exhaustion of RNA polymerase activity.
B) special protein factors.
C) terminases.
D) specific nucleotide sequences on the template strand.
________, periodic reports on the susceptibility of clinically isolated organisms to the
antibiotics in current local use, are particularly valuable for tracking the emergence of
new antibiotic-resistant strains of pathogens.
A) Antibiotic susceptibility plates
B) Antibiograms
C) Direct agglutination reports
D) Histograms
Horizontal gene transfer has been thoroughly documented for genes involved in
A) DNA replication and repair.
B) virulence and metabolic functions.
C) only very few processes.
D) translation.
Which insect functions in the host-to-host transmission of typhus?
A) rat flea
B) body louse
C) dog tick
D) deer tick
Laboratory isolation of Nanoarchaeum equitans requires the presence of
A) fatty acids.
B) oxygen.
C) Ignicoccus.
D) sunlight.
Post-translational regulation of an enzyme’s activity, such as glutamine synthetase, can
be finely controlled at varied levels due to
A) the varied strengths metabolite-regulating compounds can have with the enzyme
such as hydrogen bonding, covalent bonding, and van der Waals attractions.
B) having multiple independently functional subunits.
C) the structural strength enzymes have once properly folded compared to short-lived
and easily degradable transcripts during translational regulation.
D) weak chemical modifications of the enzyme rather than harsh protein-protein or
protein-DNA interactions.
The foul-smelling putrescine byproduct suggests activity of
A) amino acid fermentation by clostridia.
B) secondary fermentation.
C) sulfur-oxidizing bacteria.
D) syntrophic carbohydrate metabolism.
Despite ether-linked lipids being a hallmark of the Archaea, the thermophilic sulfate-
reducing bacteria in ________ also contain ether-linked lipids, which suggests they may
be more closely related to Archaea than many other groups in Bacteria.
A) Aquifex
B) Thermodesulfobacterium
C) Thermus
D) Verrucomicrobium
Which of the following must be accomplished FIRST in order to conduct RT-PCR?
A) Complementary DNA must be synthesized from double-stranded DNA.
B) Complementary DNA must be synthesized from RNA.
C) Complementary DNA must be synthesized from proteins.
D) Complementary DNA must be synthesized from single-stranded DNA.
To be most sensitive to a repellant, a methyl-accepting chemotaxis protein must be
________ methylated to initiate a ________.
A) fully / run
B) fully / tumble
C) not / run
D) not / tumble
During a growth curve of Aliivibrio fischeri, when would you expect to see the
strongest bioluminescence?
A) lag phase
B) early to middle log phase
C) late log to early stationary phase
D) middle to late stationary phase
Which of the following metabolisms is NOT found in Archaea?
A) photosynthesis
B) chemolithotrophy
C) chemoorganotrophy
D) aerobic respiration
Lysis of marine algae and cyanobacteria releases the major osmoregulatory solute,
dimethylsulfoniopropionate (DMSP), which is degraded into the most abundant organic
S compound in nature, ________.
A) dimethyl sulfide (CH3-S-CH3)
B) hydrogen sulfide (H2S)
C) gypsum (CaSO4)
D) elemental sulfur (So)
Which treatment method(s) are used in primary wastewater treatment?
A) biological
B) chemical
C) physical separation
D) biological, chemical, and physical separation
The class of macromolecules in microorganisms that contributes MOST to biomass is
A) carbohydrates.
B) DNA.
C) lipids.
D) proteins.
During periods of stratification, transfer between surface and bottom waters is
controlled by
A) mixing.
B) diffusion.
C) niche partitioning.
D) current.
Assuming exposure to the same climate, which of the following aquatic systems would
be MOST stratified?
A) 20 m deep freshwater river
B) 50 m deep marine water fjord
C) 200 m deep saltwater lake
D) 300 m deep freshwater lake
Which of the following is involved in B cell selection and tolerance?
A) clonal anergy
B) clonal deletion
C) clonal anergy and deletion
D) allelic exclusion
Hfr means high frequency of ________, and these cells are capable of transferring
genes from their ________ to other cells.
A) transformation / chromosome
B) transduction / plasmids
C) recombination / chromosome
D) transduction / chromosome