Q's from lumen website Flashcards
Exposure to air is necessary for microbial growth.
F
Lynn Margulis proposed the endosymbiotic theory of mitochondrial and chloroplast origin
T
John Snow is known as the father of epidemiology.
T
The scientist who first described cells was Robert Hooke.
T
Which bacterial structures are important for adherence to surfaces?
Fimbriae and capsules are important structures for adherence to surfaces.
Which cell wall components is unique to gram-negative cells?
Lipopolysaccharide is unique to gram-negative cells.
Bacterial cell walls are primarily composed of which of the following?
Bacterial cell walls are primarily composed of peptidoglycan.
Bacteria have 80S ribosomes each composed of a 60S large subunit and a 40S small subunit.
F
Prokaryotic cells that are rod-shaped are called _____________.
bacilli.
Which organelles is not part of the endomembrane system?
LYSOSOMES
MITOCHONDRIA
PEROXISOMES
peroxisomes
Which type of cytoskeletal fiber is important in the formation of the nuclear lamina?
intermediate filaments
Sugar groups may be added to proteins in which of the following?
Golgi
Which of the following structures of a eukaryotic cell is not likely derived from endosymbiotic bacterium?
mitochondrial DNA
mitochondrial ribosomes
inner membrane
outer membrane
outer membrane
Which type of nutrient uptake involves the engulfment of small dissolved molecules into vesicles?
active transport
pinocytosis
receptor-mediated endocytosis
facilitated diffusion
pinocytosis
Which of the following is not composed of microtubules?
desmosomes
centrioles
eukaryotic flagella
eukaryotic cilia
desmosomes
Mitochondria in eukaryotic cells contain ribosomes that are structurally similar to those found in prokaryotic cells.
T
Microfilaments are composed of _____________ monomers.
Actin
The term prokaryotes refers to which of the following?
very small organisms
unicellular organisms that have no nucleus
multicellular organisms
cells that resemble animal cells more than plant cells
unicellular organisms that have no nucleus
Among prokaryotes, there are some that can live in every environment on earth.
T
Nitrogen-fixing bacteria provide other organisms with usable nitrogen in the form of
ammonia
Pathogenic bacteria that are part of the transient microbiota can sometimes be eliminated by ___ therapy.
antibiotic
Proteobacteria is a___ within domain Bacteria.
phylum
All Alphaproteobacteria are which of the following?
oligotrophs intracellular pathogenic all of the above none of the above
oligotrophs
Which of the following refers to photosynthesis performed by bacteria with the use of water as the donor of electrons?
oxygenic
anoxygenic
heterotrophic
phototrophic
oxygenic
The length of the branches of the evolutionary tree characterizes the evolutionary distance between organisms.
T
The deeply branching bacteria are thought to be the form of life closest to the last universal
common ancestor.
Archaea and Bacteria are most similar in terms of their ________.
genetics
cell wall structure
ecology
unicellular structure
unicellular structure
They reduce carbon dioxide in the presence of nitrogen.
They live in the most extreme environments.
They are always anaerobes.
They have been discovered on Mars
They live in the most extreme environments.
Sulfolobus is a genus of Archaea. Its optimal environmental temperature ranges from 70 °C to 80 °C, and its optimal pH is 2–3. It oxidizes sulfur and produces sulfuric acid
T/F
T
Which protist is a concern because of its ability to contaminate water supplies and cause diarrheal illness?
Plasmodium vivax
Toxoplasma gondii
Giardia lamblia
Trichomonas vaginalis
Giardia lamblia
Candida albicans is the most common cause of human yeast infections.
T
Unicellular fungi are called _________
yeasts
Some fungi have proven medically useful because they can be used to produce __
antibiotics.
The components of a virus that are extended from the envelope for attachment are the
spikes.
The envelope of a virus is derived from the host’s ________.
nucleic acids
membrane structures
cytoplasm
genome
membrane structures
In naming viruses, the family name ends with ________ and genus name ends with _________.
−virus; −viridae
−viridae; −virus
−virion; virus
−virus; virion
−viridae; −virus
What is another name for a nonenveloped virus?
naked virus
scientists have identified viruses that are able to infect fungal cells.
T
A virus that infects a bacterium is called a
bacteriophage.
A ___virus possesses characteristics of both a polyhedral and helical virus
complex
A virus containing only nucleic acid and a capsid is called a__ virus or ____
naked/nonenveloped virus.
The __________ on the bacteriophage allow for binding to the bacterial cell.
tail fibres
What is the name for the transfer of genetic information from one bacterium to another bacterium by a phage?
transduction
penetration
excision
translation
transduction
A positive-strand RNA virus:
must first be converted to a mRNA before it can be translated.
can be used directly to translate viral proteins.
will be degraded by host enzymes.
is not recognized by host ribosomes.
can be used directly to translate viral proteins.
Which of the following components is brought into a cell by HIV?
a DNA-dependent DNA polymerase
RNA polymerase
ribosome
reverse transcriptase
reverse transcriptase
A virus obtains its envelope during which of the following phases?
attachment
penetration
assembly
release
attachment
Which of the following leads to the destruction of the host cells?
lysogenic cycle
lytic cycle
prophage
temperate phage
lytic cycle
An enzyme from HIV that can make a copy of DNA from RNA is called
reverse transcriptase.
Which of the followings cannot be used to culture viruses?
tissue culture
liquid medium only
embryo
animal host
liquid medium only
Which of the following tests can be used to detect the presence of a specific virus?
EIA
RT-PCR
PCR
all of the above
all of the above
Which of the following is NOT a cytopathic effect?
transformation
cell fusion
mononucleated cell
inclusion bodies
mononucleated cell
Viruses can be diagnosed and observed using an Electron microscope.
T
Cell abnormalities resulting from a viral infection are called
cytopathic effects.
Which of these infectious agents do not have nucleic acid?
viroids
viruses
bacteria
prions
prions
Both viroids and virusoids have an __genome, but virusoids require a __ to reproduce.
RNA / helper virus
Which of the following characteristics/compounds is not considered to be a phenotypic biochemical characteristic used of microbial identification?
poly-β-hydroxybutyrate
small-subunit (16S) rRNA gene
carbon utilization
lipid composition
small-subunit (16S) rRNA gene
Which of the following is an organism that obtains its energy from the transfer of electrons originating from chemical compounds and its carbon from an inorganic source?
chemoautotroph
chemoheterotroph
photoheterotroph
photoautotroph
chemoautotroph
Which of the following molecules is reduced?
NAD+
FAD
O2
NADPH
NADPH
Enzymes work by which of the following?
increasing the activation energy
reducing the activation energy
making exergonic reactions endergonic
making endergonic reactions exergonic
reducing the activation energy
To which of the following does a competitive inhibitor most structurally resemble?
the active site
the allosteric site
the substrate
a coenzyme
the substrate
Which of the following are organic molecules that help enzymes work correctly?
cofactors
coenzymes
holoenzymes
apoenzymes
coenzymes
Processes in which cellular energy is used to make complex molecules from simpler ones are described as
anabolic.
The loss of an electron from a molecule is called .
oxidation
Competitive inhibitors bind to allosteric sites.
F
During which of the following is ATP not made by substrate-level phosphorylation?
Embden-Meyerhof pathway
Transition reaction
Krebs cycle
Entner-Doudoroff pathway
Transition reaction
Which of the following products is made during Embden-Meyerhof glycolysis?
NAD+
pyruvate
CO2
two-carbon acetyl
pyruvate
During the catabolism of glucose, which of the following is produced only in the Krebs cycle?
ATP
NADH
NADPH
FADH2
FADH2
Which of the following is not a name for the cycle resulting in the conversion of a two-carbon acetyl to one ATP, two CO2, one FADH2, and three NADH molecules?
Krebs cycle
tricarboxylic acid cycle
Calvin cycle
citric acid cycle
Calvin cycle
Glycolysis requires oxygen or another inorganic final electron acceptor to proceed.
F
Most commonly, glycolysis occurs by the ________ pathway.
Embden-Meyerhof
Per turn of the Krebs cycle, one acetyl is oxidized, forming two CO2, one ATP, three NADH, and one FADH2 molecules.
T (but it’s three CO2 if you count the first one released by pyruvate to acettyl coA
Glycolysis does not use oxygen and is not oxygen dependent.
T
Which is the location of electron transports systems in prokaryotes?
the outer mitochondrial membrane
the cytoplasm
the inner mitochondrial membrane
the cytoplasmic membrane
the cytoplasmic membrane
Which is the source of the energy used to make ATP by oxidative phosphorylation?
oxygen
high-energy phosphate bonds
the proton motive force
Pi
the proton motive force
A cell might perform anaerobic respiration for which of the following reasons?
It lacks glucose for degradation.
It lacks the transition reaction to convert pyruvate to acetyl-CoA.
It lacks Krebs cycle enzymes for processing acetyl-CoA to CO2.
It lacks a cytochrome oxidase for passing electrons to oxygen.
It lacks a cytochrome oxidase for passing electrons to oxygen.
In prokaryotes, which of the following is true?
As electrons are transferred through an ETS, H+ is pumped out of the cell.
As electrons are transferred through an ETS, H+ is pumped into the cell.
As protons are transferred through an ETS, electrons are pumped out of the cell.
As protons are transferred through an ETS, electrons are pumped into the cell.
As electrons are transferred through an ETS, H+ is pumped out of the cell.
Which of the following is not an electron carrier within an electron transport system?
flavoprotein
ATP synthase
ubiquinone
cytochrome oxidase
ATP synthase
The final ETS complex used in aerobic respiration that transfers energy-depleted electrons to oxygen to form H2O is called
cytochrome oxidase.
The passage of hydrogen ions through ________ down their electrochemical gradient harnesses the energy needed for ATP synthesis by oxidative phosphorylation.
ATP synthase
All organisms that use aerobic cellular respiration have cytochrome oxidase.
T
Most ATP generated during the cellular respiration of glucose is made by oxidative phosphorylation.
T
Each ETS complex has a different redox potential, and electrons move from electron carriers with more negative redox potential to those with more positive redox potential.
T
To carry out aerobic respiration, a cell requires oxygen as the final electron acceptor
T
A cell also needs a complete Krebs cycle, an appropriate cytochrome oxidase, and oxygen detoxification enzymes to prevent the
harmful effects of oxygen radicals produced during aerobic respiration.
organisms performing anaerobic respiration use alternative electron transport system carriers for the ultimate transfer of electrons to the final non-oxygen electron acceptors.
T
Microbes show great variation in the composition of their electron transport systems, which can be used for diagnostic purposes to help identify certain
pathogens.
As electrons are passed from NADH and FADH2 through an ETS, the electron loses energy. This energy is stored through the pumping of H+ across the membrane, generating a
proton motive force.
The energy of this proton motive force can be harnessed by allowing hydrogen ions to diffuse back through the membrane by_____ using____
As hydrogen ions diffuse through down their electrochemical gradient, components of ATP synthase spin, making ATP from ADP and Pi by oxidative phosphorylation.
chemiosmosis/ ATP synthase.
Metabolism includes chemical reactions that break down complex molecules ___ and those that build complex molecules ____
(catabolism)/(anabolism)
Organisms may be classified according to their source of carbon such as
Autotrophs convert inorganic carbon dioxide into organic carbon;
heterotrophs use fixed organic carbon compounds.
Organisms may also be classified according to their energy source such as
Phototrophs obtain their energy from light. Chemotrophs get their energy from chemical compounds.
Organotrophs use organic molecules, and
lithotrophs use inorganic chemicals.
Cellular electron carriers accept high-energy electrons from foods and later serve as electron donors in subsequent redox reactions such as
FAD/FADH2, NAD+/NADH, and NADP+/NADPH are important electron carriers.
__ reactions do not require energy beyond activation energy to proceed, and they release energy. They may proceed without enzymes, but at a slow rate.
exergonic
__ reactions require energy beyond activation energy to occur.
endergonic
In cells, endergonic reactions are coupled to exergonic reactions, making the combination energetically favorable.
__are inorganic ions that stabilize enzyme conformation and function.
cofactors
___are organic molecules required for proper enzyme function and are often derived from vitamins.
Coenzymes
__inhibitors regulate enzymes by binding to an enzyme’s active site, preventing substrate binding
competitive
____ inhibitors bind to_____ , inducing a conformational change in the enzyme that prevents it from functioning.
Noncompetitive (allosteric)/allosteric sites
___occurs when the product of a metabolic pathway noncompetitively binds to an enzyme early on in the pathway, ultimately preventing the synthesis of the product.
Feedback inhibition
Which of the following is not a commercially important fermentation product?
ethanol
pyruvate
butanol
penicillin
pyruvate
Which fermentation product is important for making bread rise?
ethanol
CO2
lactic acid
hydrogen gas
CO2
Which molecule typically serves as the final electron acceptor during fermentation?
oxygen
NAD+
pyruvate
CO2
pyruvate
Which of the following is the purpose of fermentation?
to make ATP
to make carbon molecule intermediates for anabolism
to make NADH
to make NAD+
to make NAD+
___ results in the production of a mixture of fermentation products, including lactic acid, ethanol and/or acetic acid, and CO2.
Heterolactic fermentation
Fermenting organisms make ATP through the process of ___
glycolysis.
The microbe responsible for ethanol fermentation for the purpose of producing alcoholic beverages is ____
yeast (Saccharomyces cerevisiae)
_are produced by acetone-butanol-ethanol fermentation.
Industrial solvents
_ is produced by propionic acid fermentation.
Swiss cheese
_is produced by lactic acid fermentation.
Yogurt
_are produced by mixed acid fermentation.
Pharmaceuticals
_is produced by alcohol fermentation.
Bread
Fermentation does not involve an electron transport system, and no ATP is made by the fermentation process directly.
T
Fermenters make very little ATP—only two ATP molecules per glucose molecule during glycolysis.
microbes performing __fermentation produce a mixture of lactic acid, ethanol and/or acetic acid, and CO2.
heterolactic
Microbes performing __fermentation produce only lactic acid as the fermentation product
homolactic
Which of the following is the first step in triglyceride degradation?
removal of fatty acids
β-oxidation
breakage of fused rings
formation of smaller peptides
removal of fatty acids
Caseinase is which type of enzyme?
phospholipase
lipase
extracellular protease
intracellular protease
extracellular protease
Which of the following molecules is not produced during the breakdown of phospholipids?
glucose
glycerol
acetyl groups
fatty acids
glucose
Phospholipids are degraded by __, releasing fatty acids and the phosphorylated head group from the glycerol backbone.
phospholipases - Lipases and phospholipases act as virulence factors for certain pathogenic microbes.
Triglycerides are degraded by__, releasing fatty acids from the glycerol backbone.
extracellular lipases - Lipases and phospholipases act as virulence factors for certain pathogenic microbes.
Fatty acids can be further degraded inside the cell through ___, which sequentially removes two-carbon acetyl groups from the ends of fatty acid chains.
β-oxidation
The process by which two-carbon units are sequentially removed from fatty acids, producing acetyl-CoA, FADH2, and NADH is called ___
β-oxidation.
The NADH and FADH2 produced during β-oxidation are used to make ___.
ATP by oxidative phosphorylation
Which are two products of the light-dependent reactions?
glucose and NADPH
NADPH and ATP
glyceraldehyde 3-phosphate and CO2
glucose and oxygen
NADPH and ATP
Which of the following does not occur during cyclic photophosphorylation in cyanobacteria?
electron transport through an ETS
photosystem I use
ATP synthesis
NADPH formation
NADPH formation
In prokaryotes, in which direction are hydrogen ions pumped by the electron transport system of photosynthetic membranes?
to the outside of the plasma membrane
to the inside (cytoplasm) of the cell
to the stroma
to the intermembrane space of the chloroplast
to the inside (cytoplasm) of the cell
During the light-dependent reactions, which molecule loses an electron?
a light-harvesting pigment molecule
a reaction center pigment molecule
NADPH
3-phosphoglycerate
a reaction center pigment molecule
Photosynthesis always results in the formation of oxygen.
F
The enzyme responsible for CO2 fixation during the Calvin cycle is called
ribulose bisphosphate carboxylase (RuBisCO).
The types of pigment molecules found in plants, algae, and cyanobacteria are
chlorophylls and carotenoids
Heterotrophs depend on the carbohydrates produced by autotrophs, many of which are photosynthetic, converting solar energy into chemical energy.
T
Photosystems (PSI and PSII) each contain a light-harvesting complex, composed of multiple proteins and associated pigments that absorb light energy. .
T
The light-dependent reactions of photosynthesis convert __, producing ATP and NADPH or NADH to temporarily store this energy
solar energy into chemical energy
In oxygenic photosynthesis,___ serves as the electron donor to replace the reaction center electron, and is formed __ as a byproduct.
H2O/oxygen
In anoxygenic photosynthesis, other reduced molecules like __may be used as the electron donor; as such, oxygen is not formed as a byproduct
H2S or thiosulfate
__ is used in oxygenic photosynthesis when there is a need for both ATP and NADPH production.
Noncyclic photophosphorylation
If a cell’s needs for ATP outweigh its needs for NADPH, then it may carry out ___
cyclic photophosphorylation instead, producing only ATP.
The light-independent reactions of photosynthesis use the ATP and NADPH from the light-dependent reactions to fix ___ into organic sugar molecules.
CO2
Which of the following is the group of archaea that can use CO2 as their final electron acceptor during anaerobic respiration, producing CH4?
methylotrophs
methanotrophs
methanogens
anoxygenic photosynthesizers
methanogens
Which of the following processes is not involved in the conversion of organic nitrogen to nitrogen gas?
nitrogen fixation
ammonification
nitrification
denitrification
nitrogen fixation
Which of the following processes produces hydrogen sulfide?
anoxygenic photosynthesis
oxygenic photosynthesis
anaerobic respiration
chemoautrophy
anaerobic respiration
The biogeochemical cycle of which of the following elements is based on changes in solubility rather than redox chemistry?
carbon
sulfur
nitrogen
phosphorus
phosphorus
The molecule central to the carbon cycle that is exchanged within and between ecosystems, being produced by heterotrophs and used by autotrophs, is .
carbon dioxide
There are many naturally occurring microbes that have the ability to degrade several of the compounds found in oil.
T
The recycling of inorganic matter between living organisms and their nonliving environment is called a
biogeochemical cycle. Microbes play significant roles in these cycles.
In the carbon cycle, heterotrophs degrade reduced organic molecule to produce carbon dioxide, whereas autotrophs fix carbon dioxide to produce organics.
T
Methanogens typically form methane by using CO2 as a final electron acceptor during anaerobic respiration; methanotrophs oxidize the methane, using it as their carbon source.
T
In the nitrogen cycle, nitrogen-fixing bacteria convert atmospheric nitrogen into ammonia (ammonification). The ammonia can then be oxidized to nitrite and nitrate (nitrification). Nitrates can then be assimilated by plants. Soil bacteria convert nitrate back to nitrogen gas (denitrification).
T
In sulfur cycling, many anoxygenic photosynthesizers and chemoautotrophs use hydrogen sulfide as an electron donor, producing elemental sulfur and then sulfate; sulfate-reducing bacteria and archaea then use sulfate as a final electron acceptor in anaerobic respiration, converting it back to hydrogen sulfide.
T
Which of the following methods would be used to measure the concentration of bacterial contamination in processed peanut butter?
turbidity measurement
total plate count
dry weight measurement
direct counting of bacteria on a calibrated slide under the microscope
total plate count
Which of the following is the best definition of generation time in a bacterium?
the length of time it takes to reach the log phase
the length of time it takes for a population of cells to double
the time it takes to reach stationary phase
the length of time of the exponential phase
the length of time it takes for a population of cells to double
What is the function of the Z ring in binary fission?
It controls the replication of DNA.
It forms a contractile ring at the septum.
It separates the newly synthesized DNA molecules.
It mediates the addition of new peptidoglycan subunits.
It forms a contractile ring at the septum.
Filamentous cyanobacteria often divide by which of the following?
budding
mitosis
fragmentation
formation of endospores
fragmentation
The– method allows direct count of total cells growing on solid medium.
plate count
Active growth of a culture may be estimated indirectly by measuring the following products of cell metabolism:
ATP or acid from fermentation.
Most bacterial cells divide by
binary fission.
An inoculated thioglycolate medium culture tube shows dense growth at the surface and turbidity throughout the rest of the tube. What is your conclusion?
The organisms die in the presence of oxygen
The organisms are facultative anaerobes.
The organisms should be grown in an anaerobic chamber.
The organisms are obligate aerobes
The organisms are facultative anaerobes.
An inoculated thioglycolate medium culture tube is clear throughout the tube except for dense growth at the bottom of the tube. What is your conclusion?
The organisms are obligate anaerobes.
The organisms are facultative anaerobes.
The organisms are aerotolerant.
The organisms are obligate aerobes.
The organisms are obligate anaerobes
Pseudomonas aeruginosa is a common pathogen that infects the airways of patients with cystic fibrosis. It does not grow in the absence of oxygen. The bacterium is probably which of the following?
an aerotolerant anaerobe
an obligate aerobe
an obligate anaerobe
a facultative anaerobe
an obligate anaerobe
Lactobacillus acidophilus grows best at pH 4.5. It is considered an .
acidophile
A bacterium that thrives in a soda lake where the average pH is 10.5 can be classified as an .
alkaliphile
—grow best in the temperature range of 0–15 °C whereas psychrotrophs thrive between 4°C and 25 °C.
Psychrophiles
– are adapted to life at temperatures above 50 °C.
Thermophiles and hyperthemophiles
– grow best at moderate temperatures in the range of 20 °C to about 45 °C. Pathogens are usually mesophiles.
Mesophiles
Adaptations to cold and hot temperatures require changes in the composition of membrane lipids and proteins.
T
A bacterium that thrives in the Great Salt Lake but not in fresh water is probably a .
halophile
Bacteria isolated from the bottom of the ocean need high atmospheric pressures to survive. They are .
barophiles
Staphylococcus aureus can be grown on multipurpose growth medium or on mannitol salt agar that contains 7.5% NaCl. The bacterium is .
halotolerant
Which of the following is the reason jams and dried meats often do not require refrigeration to prevent spoilage?
low pH
toxic alkaline chemicals
naturally occurring antibiotics
low water activity
low water activity
Photosynthetic bacteria depend on visible light for energy.
T
Most bacteria, with few exceptions, require high moisture to grow.
T
Halotolerant pathogens are an important source of foodborne illnesses because they contaminate foods preserved in salt.
T
EMB agar is a medium used in the identification and isolation of pathogenic bacteria. It contains digested meat proteins as a source of organic nutrients. Two indicator dyes, eosin and methylene blue, inhibit the growth of gram-positive bacteria and distinguish between lactose fermenting and nonlactose fermenting organisms. Lactose fermenters form metallic green or deep purple colonies, whereas the nonlactose fermenters form completely colorless colonies. EMB agar is an example of which of the following?
a selective medium only
a differential medium only
a selective medium and a chemically defined medium
a selective medium, a differential medium, and a complex medium
a selective medium, a differential medium, and a complex medium
Haemophilus influenzae must be grown on chocolate agar, which is blood agar treated with heat to release growth factors in the medium. H. influenzae is described as ________.
an acidophile
a thermophile
an obligate anaerobe
fastidious
fastidious
Blood agar contains many unspecified nutrients, supports the growth of a large number of bacteria, and allows differentiation of bacteria according to hemolysis (breakdown of blood). The medium is
complex and differential.
Rogosa agar contains yeast extract. The pH is adjusted to 5.2 and discourages the growth of many microorganisms; however, all the colonies look similar. The medium is
complex and selective.
-media contain added essential nutrients a specific organism needs to grow
Enriched
-defined media contain only chemically known components.
Chemically
-media favor the growth of some microorganisms while inhibiting others.
Selective
-media help distinguish bacteria by the color of the colonies or the change in the medium.
Differential
