How can we help?

You can also find more resources in our Help Center.

355 terms

Microbiology Unit 1 Self Quizzes & True/False

Self quizzes and true/false questions for Unit test #1. Chapters #1, 3, 5, 6, and 7
STUDY
PLAY
CHAPTER 1 SELF QUIZ
~~~~~~~Next 39 note cards~~~~~~
Organisms without a membrane-bound nucleus and without compartmentalization are called what?
Prokaryotes
Organisms with a membrane-bound nucleus and membrane-bound organelles are called what?
Eukaryotes
What scientific advances influenced microbial classification?
The use of electron microscopy to study detailed structures of microbial cells, the determination of the biochemical and physiological characteristics of many microbes, and the sequencing of nucleic acids and proteins from a wide variety of microbes
Comparison of ribosomal RNA from a variety of organisms led to what classification schemes?
Two-domain classification scheme
How would you best describe bacteria?
Cell wall is composed of peptidoglycan
How would you best describe archaea?
Usually live in extreme environments, exhibit unusual metabolic characteristics, and plasma membrane composed of unique lipids
Name a microorganism that the domain Eukarya includes
Protists
Name a major type of protist
Algae, protozoa, and slime and water molds
What is a diverse group of microorganisms that are multicellular, form hyphae, and absorb nutrients from the environment called?
Fungi
What do viruses require?
Host cells to replicate
What is the name for an infectious protein that causes spongiform encephalopathies?
Prions
In the scientific method, and educated guess used to explain observations is called what?
A hypothesis
What would microbiologists consider to be an important attribute of life?
Reproduction
What was most likely the first self-replicating molecule on the primitive earth?
RNA
Why was RNA most likely the first self-replicating molecule?
It can catalyze chemical reactions, it can regulate gene expression, and ATP (the energy currency of the cell) is composed of a ribonucleotide
The universal phylogenetic tree was constructed from comparison of which molecule amongst diverse organisms?
SSU rRNA
According to the universal phylogenetic tree...?
The eukarya and the archaea are more closely related and evolved from a common ancestor after the bacteria
Describe the origin of the eukaryotic organelles?
The endosymbiotic hypothesis
The hydrogen hypothesis describe the evolution of which eukaryotic organelle?
Mitochondria
A major source of genetic diversity in bacteria is what?
Horizontal gene transfer
Why is the traditional biological species concept applied to some eukaryotes not valid for bacteria?
Because bacteria reproduce asexually
What is the name for a collection of bacterial or archaeal strains that share many stable properties and differ significantly from other groups of strains?
Species
What are important methods to microbiologists?
Microscopy, culture techniques, and genomic analysis
Who constructed simple microscopes, observed bacteria and protists, and reported his findings to the Royal Society of London?
Antony van Leeuwenhoek
What observation made by Francesco Redi refuted the idea of spontaneous generation?
He covered pieces of meat and they did not produce maggots spontaneously
Which scientists contributed to disproving spontaneous generation?
Francesco Redi, John Needham, and Lazzaro Spallanzani
Which scientist linked silkworm disease with a fungus?
Agostino Bassi
What the processes of heating liquids to destroy undesirable microbes called?
Pasteurization
Who first used phenol in surgery to prevent microorganisms from entering the wounds?
Joseph Lister
Make a statement to best illustrate Koch's postulates?
The suspected organisms are isolated and grown in pure culture
Why is agar an ideal solidifying agent for growing bacteria?
Because it is not broken down by most bacteria, it is in liquid form at 100 degrees celsius, it is in a solid form at 50 degrees celsius
Who was the first scientist to knowingly use attenuated bacteria in vaccination?
Pasteur and Roux
Name major discoveries in the field of immunology?
Injection with attenuated microorganisms that provided immunity, discovery of antibodies, and the discovery of immune system cells
Who made the discovery that soil bacteria could oxidize iron, sulfur, and ammonia to obtain energy?
Sergei Winogradsky
What is the name for the genetic information that an organism contains?
Genome
What is the name for molecules made by combining two or more different DNA molecules together?
Recombinant DNA molecules
Which field of microbiology that studies the spread of communicable disease, detects outbreaks, and implements appropriate control measures called?
Epidemiology
Which field of microbiology that studies the role of divers microorganisms in the environment?
Microbial ecology
Which field of microbiology researches new uses for microbes and and ways of culturing and isolating their products?
Industrial microbiology
CHAPTER 1 TRUE/FALSE
~~~~~~Next 39 note cards~~~~~~
Microorganisms are always one millimeter or less in diameter
False
Classification of microbes is difficult due to their vast diversity
True
The five-kingdom classification system is widely accepted and used in the field of microbiology
False
Viruses, viroids, and virusoids are examples of cellular entities studied by microbiologists
False
All bacteria are pathogens, or disease-causing organisms
False
The archaea are different than the bacteria in regards to cell wall composition and plasma membrane lipids
True
The domain eukarya includes some microbial members
True
Together, algae and cyanobacteria produce about 75% of planet's oxygen
True
Most fungi are unicellular
False
Viruses cannot live outside a host cell
True
Scientific theories are proven absolutely with many observations and experiments
False
Hypotheses that are refuted through experimentation are of no value to the scientific community
False
Unlike other fields of microbiology, the study of microbial evolution does not follow the scientific methods
False
The primitive earth was hospitable for the evolution of early life
False
Organisms alive today can assist scientists in understanding the origins of life
True
Microbial fossils indicate that microbial life began approximately 3.5 billion years ago
True
Due to its ability to do cellular work, DNA was likely the first self-replicating molecule on the planet
False
In the RNA world, RNA was capable of storing, copying, and expressing genetic information, as well as catalyzing other chemical reactions
True
The appearance of cyanobacteria-like cells released oxygen and altered the Earth's atmosphere allowing the evolution of aerobic respiration
True
The universal phylogenetic Tree is based on comparison of small subunit rRNA molecules
True
Evolutionary distance between organisms can indicate definitely when they diverged from one another
False
The last universal common ancestor (LUCA) is well known and characterized
False
Organisms with similar nucleotide sequences are more distantly related evolutionarily
False
The endosymbiotic hypothesis is generally accepted as the origin of eukaryotic organelles
True
In the hydrogen hypothesis, if an endosymbiont developed the capacity to perform aerobic respiration, it evolved into a mitochondrion
True
Sexual reproduction is the primary means of generating genetic diversity in the archaea
False
The bacteria and the archaea are easily classified using the biological species concept of eukaryotes
False
The linnaean binomial classification system is applied to the bacteria and the archaea
True
Microbiology is defined both by the organisms it studies and the tools used to study them
True
Culturing microorganisms outside of their natural environment provides valuable information about their ecology
False
Scientists have been observing organisms with microscopy since the 1600s
True
The theory of spontaneous generation advanced the field of microbiology
False
Many scientists throughout the 1700s to 1800s disproved the theory of spontaneous generation through repeated experimentation and observations
True
The belief in spontaneous generation was an obstacle to the development of microbiology as a scientific discipline
True
Pasteurization is widely used today to destroy undesirable microbes in food and beverages
True
The use of antiseptics in the 1800s transformed the field of surgery and provided strong indirect evidence for the role of microorganisms in disease
True
The first direct demonstration of the role of bacteria in causing disease came from the study of anthrax
True
Koch's postulates are applicable and feasible for all microbes
False
Injection of attenuated virus is usually lethal
False
CHAPTER 3 SELF QUIZ
~~~~~~Next 33 note cards~~~~~~
In what way are bacterial and archaeal cells similar?
In cellular organization
How are bacterial cells that grow in irregular groups and divide in random planes are characterized as what?
Staphylococci
Which characteristics contribute to variation in bacterial and archaeal size and shape?
Surface area-to-volume ratio, presence of filamentous structures, and cytoskeletal elements
Describe the layers of bacterial cellular organization (starting internally and working outward)
Cytoplasm, plasma membrane, cell wall, and capsule
What is the purpose of the nucleoid in bacterial and archaeal cells?
Localization of genetic material
What is the function of the plasma membrane in bacterial cells?
To detect and respond to chemicals in the surrounding environment, to provide a selectively permeable barrier, and to facilitate important metabolic processes
How would you best describe the current understanding of the fluid mosaic model of membrane structure?
Phospholipid bilayer with peripheral and integral membrane proteins
Why are hopanoids important to bacterial cells?
Because they likely provide membrane stability
How would you best describe the bacterial cell wall?
It protects the cell from osmotic lysis, contributes to pathogenicity, and site of action of several antibiotics
Most gram-positive bacterial cells exhibit which characteristics?
Thick layer of peptidoglycan with teichoic acids and small periplasmic space
Most gram-negative bacterial cells exhibit which characteristics?
Thin layer of peptidoglycan without teichoic acids, large periplasmic space, and outer membrane
What is the function of lipopolysaccharides (LPSs) on gram-negative bacterial cells?
To assist in evading the host immune response, to contribute to the negative charge on the cell surface, and to create a permeability barrier
Why do gram-positive cells stain purple?
Because ethanol shrinks the peptidoglycan pores and prevents loss of crystal violet
If bacterial cells treated with lysozyme are placed into a hypotonic solution, what would be the result?
The cells would likely swell and lyse
How do slime layers assist bacterial cells?
By facilitating motility
What is a unique feature of archaeal cell s-layers?
They are located just outside the plasma membrane
Why are archaeal membrane lipids unique?
Because they contain branched hydrocarbons derived from isoprene units, they are attached to glycerol by ether links, and they are often composed of C20 diethers and C40 tetraethers
What is the best way to describe the most common archaeal cell wall?
S-layer composed of glycoproteins or proteins
How would you best describe the function of the bacterial cytoskeleton?
It facilitates cell division, localizes proteins to certain sites in the cell, and determines cell shape
Ladderlane lipids compose which of the following bacterial organelles?
Anammoxosomes
When aquatic bacteria are living under phosphorus-limited conditions with abundant carbon availability, which of the following structures may be visible via microscopy?
Glycogen inclusions
Which structures allow aquatic bacteria to orient themselves in the earth's magnetic field?
Magnetosomes
What is the function of ribosome in the bacterial cell?
To synthesize proteins
Give a true statement regarding plasmids
The replicate autonomously
What is the name of a bacterial cell with flagella spread evenly over the whole surface?
Peritrichous
What is the primary function of bacterial flagella?
Motility
How do archaeal flagella differ from bacterial flagella?
They are thinner than bacterial flagella, they are composed of multiple subunit types, and their flagellum is solid instead of hollow
What is flagellar movement driven by?
Proton-motive force
Which bacterial movements are type IV pili associated with?
Twitching motility
What allows for bacterial cells to sense a chemical gradient and respond appropriately?
Chemoreceptors
What is a true statement regarding bacterial endospores?
Endospores survive in nutrient limited conditions
Which structure of the endospore contributes to its resistance to heat and other lethal agents?
The exporium and spore coat, the inner membrane, and the core
What has viviparity been observed in?
Epulopscium fishelsoni
CHAPTER 3 TRUE/FALSE
~~~~~~Next 24 note cards~~~~~~
Bacteria and archaea are uniform in shape and size
False
Pleomorphic cells are variable in shape and lack a single, characteristic form
True
Larger cells have a greater surface area-to-volume ratio
False
Bacterial and arachaeal cells share a common cell organization
True
Peripheral proteins in the plasma membrane are easily removed and comprise up to 30% of membrane proteins
True
Scientists agree upon all aspects of the fluid mosaic model
False
At higher temperatures, bacterial phospholipids have more saturated fatty acids
True
Hopanoids in bacterial cell membranes contribute significantly to the world's petroleum formation
True
Peptidoglycan is common to both gram-positive and gram-negative bacterial cells
True
Periplasmic space comprises a larger portion (20-40%) of the gram-positive cell wall
False
The component of lipopolysaccharides (LPSs), lipid A, elicits an immune response by an infected host
False
In the gram staining preocedure, iodine is used to promote dye retention
True
Capsules are layers outside the cell wall that are well organize and not easily washed off
True
S-layers are currently being studies for their potential use in the field of nanotechnology
True
Archaeal membrane lipids are capable of forming pentacyclic rings
True
Archaeal cell walls have the same chemical composition as bacterial cell walls
False
Eukaryotic and bacterial cytoskeletons have analogous components
True
Polyphosphate granules store phosphate in bacterial cells living in nutrient-limited conditions
True
Archaeal and bacterial ribosomes have the same make up and size
False
All bacteria have one circular chromosome
False
Bacteria cells can lose plasmids spontaneously
True
Type IV pili are involved in bacterial motility and uptake of DNA during transformation
True
Chemotaxis is best described as random, aimless movement in bacteria and archaea
False
Endospore position in the sporangium is valuable for identification of some bacterial species
True
CHAPTER 5 SELF QUIZ
~~~~~~Next 29 note cards~~~~~~
The genetic material found in a virion is usually what?
Either DNA or RNA
Viral particles are composed of what?
DNA or RNA, a coat of protein, and layers of carbohydrates, lipids and additional proteins
What is the best microscopic methods for studying viruses?
Electron microscopy
What is the function of the viral capsid?
To the protect the viral genome
The Tobacco mosaic virus exhibits which type of capsid symmetry?
Helical
An example of a virus that exhibits binal symmetry is known as what?
Bacteriophages
Viral spikes or peplomers are involved in what?
Attachment
Which structures are associated with the influenza virus?
Neuraminidase enzyme, hemagglutinin protein, and glycoproteins
The most common viral nucleic acid types are what?
dsDNA and ssRNA
What is the first step in the generalized viral life cycle?
Attachment of virus to host cell
What is viral host specificity most likely attributed to?
Interaction between receptors on the surface of the host cell and ligands on the surface of virions
Which mechanisms do eukaryotic viruses enter host cells through?
Through fusion of the viral envelope with the host cell membrane, entry by endocytosis, and injection of nucleic acid
Which types of viruses must carry their own replication enzymes in their nucleocapsid?
RNA viruses only
Where does the energy that is required for bacteriophage assembly come from?
Host metabolic activity
What is a common virion release method observed in enveloped viruses?
Budding
What is the name of the relationship with the host cell in which the virus remains within the host without destroying it called?
Lysogeny
What does an advantage of lysogeny to the host include?
Resistance to superinfection
When more phage are present in the environment than there are host cells, which type of host relationship is most desirable?
Lysogenic preferred
What are microscopic and/or macroscopic damages to host cells caused by eukaryotic viruses called?
Cytopathic effects
What is the name for a type of viral infection in which there is a low release of virions without cell death?
Chronic infection
What cellular genes required for normal growth, but when mutated or overexposed, cause carcinogenesis?
Proto-oncogenes
Which of the following viruses is NOT definitely linked to causing cancer in humans?
Rabies virus
Which methods can be used to cultivate plant viruses?
Grow in cultures of plant cells lacking cell walls, mechanically break leaves to expose cells to infection, or graft diseased part onto a healthy plant
What can be used to determine direct counts of viral particles?
Epifluorescence microscopy
What is an indirect method of counting animal viruses?
Hemagglutination assay
The number of plaque-forming units (PFUs) is calculated from a viral plaque assay by.....?
Multiplying the number of plaques per volume by the dilution
What is teh dilution taht contains the number of viral cells large enough to destroy 50% of the host cells or organisms called?
The lethal dose
What are infectious RNAs that primarily infect plants called?
Viroids
What are infectious proteins responsible for bovine spongiform encephalopathy called?
Prions
CHAPTER 5 TRUE/FALSE
~~~~~~Next 35 note cards~~~~~~
Viruses are considered to be living organisms
False
Scientists classify viruses based on genome structure, life cycles, morphology, and genetic relatedness
True
Most viruses are approximately the same size as bacteria (0.2 to 2 micrometers)
False
Hos-independent growth has never been observed in either the bacterial or archaeal viruses
False
The size of a helical capsid is influenced by both its protomores and the nucleic acids enclosed within the capsid
True
The icosohedral capsid maximizes efficiency and requires few genes for its coding
True
An envelope is present in all viruses
False
Spikes can be used to identify many types of viruses
True
All virions lack enzymes
False
Most DNA viruses use dsDNA as their genetic material
True
Many RNA viruses have segmented genomes with each segment coding for a protein
True
Viral attachment to the host cell is a random process
False
Variation in receptors used by a virus for attachment is partly responsible for host specificity
True
All viruses inject their nucleic acid into the cytoplasm of their host, leaving the capsid outside and attached to the cell wall
False
Human immunodeficiency virus (HIV) enters the host cell by fusing directly with the host cell plasma membrane
True
DNA and RNA viruses replicate using the same processes
False
Bacteriophages are assembled in the host cytoplasm
True
All animal viruses are assembled in the cytoplasm
False
Many nonenveloped viruses lyse their host cells at the end of the intracellular phase
True
When viral cells are released via budding, the host cell may survive and continue releasing virions for some time
True
Actin filaments in the cytoskeleton can aid in the release of eukaryotic viruses
True
Temperate phages must release from the host cell via lysis
False
Temperate phages can integrate their genome with the host genome
True
Host cells that are infected with a temperate virus cannot be infected by other virions of the same type
True
temperate phages can alternate between lysogenic and lytic stages
True
Lysogeny enables survival of host cells in an environment with low multiplicity of infection (MOI)
False
A chronic infection is a situation in which a virus slowly releases virions without killing the cell
True
Most human viruses associated with cancer have dsDNA genomes
True
Some strains of human papillomavirus (HPV) can cause cervical caner
True
Tumor activator proteins promote formation of tumors in human dsDNA viruses
False
Viruses are easily cultivate in agars and broths, much like bacteria
False
Plaque assays determine viral numbers based on infectivity of the virus
True
The number of plaque-forming units (PFUs) is equal to the number of viruses because all virions are infective
False
The infectious dose (ID60) of a virus is the dose that, when given to a number of hosts, causes and infection of 50% of the hosts under particular conditions
True
Viroids, or infectious RNAs, cause many important plant diseases
True
CHAPTER 6 SELF QUIZ
~~~~~~Next 28 note cards~~~~~~
Name 3 macronutrients required in large amounts for microbial nutrition
Carbon, Iron, Phosphorous
What are nutrients required by microbes only in small amounts called?
Micronutrients
What is an organism that obtains carbon, hydrogen, oxygen, and electrons from organic molecules?
A heterotroph
What are organisms that use carbon dioxide (CO2) as their sole or principal source of carbon?
Autotrophs
What is an organism that uses light for energy and carbon dioxide as a carbon source?
A photolithoautotroph
What are microbes that are used industrially to make foods and beverages called?
Chemoorganoheterotrophs
Purple nonsulfur and green bacteria are classified as what?
Photoorganoheterotrophs
Microbes use which processes to obtain nitrogen?
Metabolism of amino acids, incorporation of ammonia directly, and reduction of nitrate to ammonia
Phosphorous is required in microbial metabolism for what?
Nucleic acids
Organic compounds that cannot be synthesized by an organism but are essential for growth are called what?
Limited nutrients
What does a major class of growth factors include?
Amino acids, purines and pyrimidines, and vitamins
Movement of molecules from a region of high concentration to a region of low concentration without the expenditure of energy is known as what?
Passive diffusion
Diffusion involving carrier proteins that created channels through the plasma membrane is called what?
Facilitated diffusion
The rate of transport of molecules across the membrane via facilitated diffusion increases as....?
the concentration gradient of the molecule increases
Facilitated diffusion is most prominent in which of the following groups?
The eukarya
What is the transport of solute molecules against a concentration gradient with the input of metabolic energy?
Active transport
What is lactose entering the E. coli cell along with a proton an example of?
Symport
What is the name for an energy-dependent form of transport that chemically modifies a molecule as it is brought into the cell?
Group translocation
The phosphoenolpyruvate, sugar phosphotransferase system (PTS), is an example of what?
Group translocation
Microbes in an iron-limited environment will secrete _______________ externally to bind ferric iron
Siderophores
Growth media that contains some unknown ingredient in which the exact chemical composition is not known in called what?
Complex media
What is a type of media that distinguishes among different groups of microbes and can aid in tentative identification?
Differential media
Blood agar distinguishes between hemolytic and nonhemolytic bacteria as well as growing fastidious microbes. For these reasons, blood agar is what?
Both enriched and differential
Mannitol salt agar's high concentration of salt grows only staphylococci. In addition, some staphylococci that use mannitol as a carbon source turn the medium yellow. For these reasons, mannitol sugar is what?
Both selective and differential
What is a population of microbial cells arising from a single cell, representing a single species called?
Pure culture
What is an appropriate qualitative method for isolating microbe into a pure culture?
The streak plate
A microbiology student would like to quantify the number of bacterial cells growing in her sample of nutrient agar. Which method will help her with this goal?
Serial dilution
The most active bacterial cells on the colony would be found where?
Growing along the edge of the colony
CHAPTER 6 TRUE/FALSE
~~~~~~ Next 28 note cards~~~~~~
Magnesium (Mg+) is an example of a macronutrient required by microbes
True
Calcium (Ca2+) is an example of a micronutrient required by microbes
False
Electrons provided by organic carbon sources are used in oxidation-reduction and in the electron transport chain
True
Heterotrophs can use organic molecules as a source of carbon, hydrogen, oxygen, and electrons
Trues
Most microbes are capable of metabolizing only a narrow range of organic compounds
False
Carbon dioxide (CO2) serves both as a source of carbon and a source of electrons for autotrophs
False
Lithographs use reduced inorganic substances as a source of electrons
True
All pathogens are chemoorganoheterotrophs
True
All microbes are classified into only one nutritional type
False
Nitrogen is required for the synthesis of amino acids, purines, and pyrimidines
True
Phosphorous is required for the synthesis of the amino acids cystein and methionine
False
Vitamins act as enzyme cofactors and are required only in very small amounts
True
Some microorganisms are able to synthesize large quantities of vitamins
True
Uptake of nutrients into microbial cells is random and non-specific
False
Transport of nutrients via group translocation has been observed in all three domains
False
A large concentration gradient is required to transport molecule across a membrane via passive diffusion
True
The microbial cell membrane is permeable to all substances
False
Facilitated diffusion reaches a maximum rate due to saturation of carrier proteins
True
Membrane permeases are specific for particular solutes
True
ATP-binding cassette transporters are involved in both import and export of substances across the cell membrane
True
Microorganisms rarely have more than one transport system for a nutrient
False
Phosphoenolpyruvate, sugar phosphotransferase systems (PTSs), are widely distributed in bacteria
True
Siderophores are released when iron is abundant in a microbe's environment
False
Examples of complex media include nutrient broth, trypic soy broth, and MacConkey agar
True
Agar is useful to solidify media because most microorganisms can degrade it
False
Selective media often contains dyes that suppress the growth of one type of bacteria
True
It is not possible to isolate microbes as a pure culture in the laboratory
False
A colony is composed of clones resulting from one bacterium
True
CHAPTER 7 SELF QUIZ
~~~~~~Next 45 note cards~~~~~~
Sexual reproduction is a characteristic of which domain?
Eukarya only
Which reproductive method is common to bacteria?
Binary fission, budding, and formation of uninucleoid spores
Replication is the bacterial chromosome is........?
Bidirectional
How would you best describe chromosomal partitioning of daughter cells in bacterial reproduction?
It is pushing of chromosomes to opposite sides by RNA polymerase, condensation of daughter chromosomes pull the DNA opposite sides, and a cytoskeletal protein MreB moves the DNA to opposite poles
What is the most critical step in cytokinesis?
Assembly of the z ring
Where does peptidoglycan synthesis start in?
Cytoplasm
What are autolysins involved in?
Degrading the glycosidic bonds between peptidoglycan molecules
What does the new cell wall in reproducing rods form?
Along the sides of the cell but not at the poles
Organisms incubated in a closed culture vessel with a set volume of media is known as a(n).....?
Batch culture
Cells begin synthesizing new component during which phase?
Lag
During which phase do microorganisms grow and divide at their maximum rate?
Exponential
Balanced growth in which all cellular constituents are manufactured at a constant rate, occurs during which phase?
Exponential
Why do microbial populations enter the stationary phase?
Because of nutrient limitation, accumulation of toxic waste products, and limited oxygen availability
What is the name of proteins that make the cell more resistant to damage by starvation and other stressful conditions?
Starvation proteins
The number of viable cells decreases exponentially in which phase?
Death
In death phase.......?
The number of living cells declines exponentially, cell become viable but nonculturable (VBNC) and undergo programmed cell death
How would you define the number of generations per unit time?
The mean growth rate
Which variables are important to calculation the microbial mean growth rate?
Initial population number, the population number at time (t), and the number of generation in time (t)
Which method would be best for counting the number of protists in a water sample?
Coulter counter
What is the best method for counting living bacterial and archaeal cells?
The Petroff-Hauser counting chamber
Give examples of viable counting methods
Streak plate, pour plate, and membrane filtration
What is the most rapid and accurate method for measuring cell mass?
Spectrophotometry
What will a more turbid broth culture of bacterial cells result in?
A high absorbance reading with the spectrophotometer
Bacterial cells growing in a chemostat will grow more with which change?
Increasing the dilution rate
Turbidostats work by what?
Maintaining a desired cell density
If a bacterial cell is placed into a hypertonic solution, then what?
Water will move out of the cell and the cell will shrink
Microbial cell respond to osmotic stresses by.........?
Opening and closing mechanosensitive (MS) channels, storing compatible solutions inside the cell, and using a contractile vacuole to expel excess water
Organisms that do not require oxygen for growth but grow better in its presence are called what?
Facultative anaerobe
What are organisms that grow optimally at temperatures at 55 degrees celcious or higher?
Thermophiles
What are organisms that grow optimally within a pH range of 0 and 5.5 called?
Acidophiles
How do acidophiles survive in low pH environments?
The survive by pumping protons outside the cell if they get in
Why are microbes vulnerable to high temperatures?
Because high temperatures inactivate enzymes responsible for metabolism
Thermophiles have which adaptations for survival at high temperatures?
Adaptations are that they have heat-stable enzymes and proteins, they have lipids that span the membrane and form a rigid monolayer, and they have saturated membrane lipids
Photosynthetic protists are most likely.......?
Obligate aerobes
Which enzymes protect microbes against toxic oxygen (O2) products?
Catalase
How can microbes be grown in anaerobic conditions?
They can be grown by removing oxygen chemically with a palladium catalyst, by removing air from the growth chamber with a vacuum, and by adding carbon dioxide (CO2) to the growth chamber to drive out oxygen
How are organisms that grow in the deepest trench of the Pacific Ocean classified as?
Piezophilic
Which form of radiation is most harmful to microbes?
Ionizing radiation
Why can ultraviolet (UV) radiation kill microorganisms?
Because it damages DNA by forming thymine dimers
Why is visible light damaging to microbial cells?
Because it generates singlet oxygen and oxidizes cells
What is the purpose of the extracellular polymeric substance (EPS) matrix created by biofilms?
To stick more stably to a surface
What is a density-dependent chemical communication between microbes known as?
Quorum sensing
When for Vibrio fischeri populations inside warm-water squids bioluminesce?
When N-acylhomoserine lactone (AHL) reached threshold levels
CHAPTER 7 TRUE/FALSE
~~~~~~Next 47 note cards~~~~~~
Sexual reproduction is a characteristic of all domains in life
False
In E. coli cytokinesis, Z-ring formation can only occur in the middle of the cell that lacks MinCDE
True
Chromosome and plasmid segregation utilizes the same types of proteins
False
Microbial shapes are fixed and unchanging
False
Penicillin binding proteins (PBPs) link strands of peptidoglycan together in cellular growth
True
Spherical cells build new peptidoglycan only at the septum during division
True
The cytoskeleton protein MreB plays an essential role in determining cell diameter during elongation of rod cells
True
Microbial cells experience the greatest increase in numbers during lag phase
False
Microbial cells begin to replicate their DNA in lag phase
True
During exponential (log) phase, microbes grow and divide at the maximum rate possible
True
The rate of growth is constant during exponential (log) phase
True
Unbalanced growth results when nutrient levels or other environmental conditions change
True
The rate of growth increases as the concentration of a limiting nutrient increases
True
Starvation proteins are made in response to stressful conditions during death phase
False
viable but nonculturable cells (VBNCs) are easy to grow under laboratory conditions
False
In programmed cell death, it is hypothesized that some cells within a population die to make their nutrients available for other cells
True
If a population of two bacterial cells doubles every two minutes, 16 cells will be present after six minutes
True
The mean generation time is the reciprocal of the mean growth rate
True
Direct microscopic counts and culture counts of environmental samples are approximately the same
False
Flow cytometry can count cells of different sizes
True
The number of colony forming units in a sample is the same as the number of organisms in the sample
False
Plate counts are an accurate way to estimate bacterial cell numbers in environmental samples
False
Because of the small size of bacterial cells, determining dry weight provides an accurate measure of cell mass
False
A continuous culture system maintains bacterial cells in a state of exponential growth
True
In a chemostat, the dilution rate is dependent upon both the flow rate and the volume of the vessel
True
In a chemostat, the cell density of a microbial population increases with a high dilution
False
A turbidostat operates best at high dilution rates
True
A bacterial cell placed in hypotonic solution will swell and lyse
True
Hyperthermophilic organisms live optimally between 80 and 113 degrees celcius
True
Alkalophiles grow optimally between pH 0 and 5.5
False
Many microbes keep the osmotic concentration of their cytoplasm somewhat above that of the habitat so that the plasma membrane is always pressed firmly against their cell wall
True
Halophilic organisms are capable accumulating large quantities of potassium and chloride in order to remain hypertonic to their environment
True
Water activity (aw) is a measure of the degree of water availability to microbes
True
Xerophilic organisms grow best at low water activity
True
A pH of 2 is twice a great as a pH of 1
False
Acid-shock proteins prevent denaturation of proteins under acidic conditions
True
At high temperatures, microbial membranes solidify
False
Bacteria and archaea are capable of growing at much higher temperatures than eukaryotes
True
Almost all human pathogens are mesophiles
True
Psychrophilic bacteria and fungi are major causes of refrigerated food spoilage
True
Obligate anaerobes are usually killed in the presence of oxygen
True
Strict anaerobes contain the enzymes superoxide dismutase (SOD) and catalase
False
It is not possible to culture microbes under anaerobic conditions in the laboratory
False
As the wavelength of electromagnetic radiation increases, the energy of the radiation increases
False
Carotenoid pigments protect cell against photo-oxidation
True
Biofilms are resistant to antibiotic treatments
True
AHLs regulate quorum sensing and bioluminescence amongst Vibrio fischeri, endosymbionts of the warm-water squid
True