A food spoilage process called _____ results in the release of foul smelling amine compounds |
Putrification |
Temperature and relative humidity are important intrinsic factors in determining the rate of food spoilage. |
False |
Filtration is sometimes used to remove organisms from beer because it has less effect on flavor than pasteurization. |
True |
Growth of yeasts and molds will be favored in more acidic foods. |
True |
Which of the following can function better at a lower pH? |
Yeasts and molds |
A major organism involved in the production of ergot is |
Claviceps purpura |
Ergotism involves microorganism production of |
Hallucinogenic alkaloids |
The first person to use heating processes to preserve food was |
Nicholas Appert |
The use of plastic film to wrap meat products can result in increased surface growth of microorganisms in part because of exposure to |
Oxygen |
Lysozyme is an important antimicrobial substance found at high levels in which food? |
Eggs |
Microorganisms that grow in media with low water availability are called ____ |
Xerophilic |
Atmosphere is important in food spoilage; high H2S tends to reduce spoilage, while high CO2 tends to increase spoilage. |
False |
Nisin |
All of the choices (Is a small amphibilic peptide that disrupts membrane integrity and function, Is a food additive that blocks the growth of some gram positive bacteria, Is a bacteriocin produced by some strains of lactococcus lactis) |
Which of the following represents ways in which canned foods can undergo spoilage? |
All of the choices (Spoilage before canning, As a result of underprocessing during canning, Leakage of contaminated water through can seams during cooling) |
A chemical that is effective in preserving foods with low pH such as bread is |
Sodium propionate |
Gamma irradiation has been used to sterilize certain types of foods. There are however certain limitations on its effectiveness. One of these is that it will only work on |
Moist foods |
Which of the following helps preserve food by controlling microbial access to water? |
All of the choices (drying, addition of salt, addition of sugar) |
Pasteurization of milk |
Usually eliminates all disease-causing organisms |
To control pathogenic and disease-causing organisms, spices can be fumigated using |
Ethylene oxide |
A major chemical used to preserve meat product is |
Nitrite |
Which of the following represents a different principle for food preservation? |
Heating |
The term radappertization is used to describe food preservation by |
Gamma irradiation |
Sometimes ____ beams are used to irradiate foods in place of gamma radiation because the process does not generate radioactive waste |
Electron |
The swelling of a food-containing can is usually due to the production of ___ by spoilage microbes. |
Carbon dioxide gas |
The conventional low-temperature holding procedure used in the pasteurization of milk involves holding the milk at 68.2 degrees C for ___ minutes. |
30 |
To control microbial growth in a food, one can decrease water availability by adding |
Sugar or salt |
If food-borne disease transmission does not require growth of the microorganism after ingestion because the toxic substances are already present in the food as a result of previous growth then it is referred to as a food-borne ___ |
Intoxication |
If food-borne disease transmission requires ingestion of the pathogen, followed by growth of the organisms and release of toxins in the intestine it is referred to as a food-borne ___ |
Infection |
Staphylococcus aureus, once it grows in a food, produces toxins that are not usually inactivated by heating. |
True |
A major fungal genus that produces aflatoxin is |
Aspergillus |
Aflatoxins are planar, ringed compounds that interact with DNA by ____ and cause frameshift mutations. |
Intercalation |
Clostridium botulinum and bacillus cereus are important disease-causing microorganisms of food which cause |
Intoxications |
A major organism considered to cause food-borne illness is |
Salmonella |
The largest meat recall in U.S. history was prompted by the discovery of contamination by |
Listeria monocytogenes |
Food-borne pathogens are most commonly identified by |
Standard culture techniques |
Which of the following is true about molecular detection of microoroganisms in foods? |
All of the choices (detect presence of single specific pathogen + viruses that are not easily cultured + slow growing pathogens) |
Pulsed-field gel electrophoresis can be used to link a particular pathogen associated with disease outbreaks in a specific food source. |
True |
The polymerase chain reaction can detect as few as 10 toxin-producing E. coli in a population of 100,000 microorganisms isolated from soft cheese samples. |
True |
The process of racking, used in the production of wines, involves |
removal of sediments |
The production of natural carbon dioxide by yeasts after a wine is bottled results in |
Champagne |
The process of beer lagering involves |
Aging |
A microorganism that has been used in the production of sour mash whiskey is |
lactobacillus delbrueckii |
Bread products can be spoiled by the growth of Bacillus species that produce |
Ropiness |
Mashing is a process involving |
Carbohydrate hydrolysis |
Which of the following determines whether or not a wine is considered to be dry? |
The amount of free sugar after fermentation |
Streptococcus thermophilus and lactobacillus bulgaricus contribute to the flavor of yogurt by diacetyl during the fermentation of lactose. |
True |
Some fermented dairy products have been suggested to have beneficial effects, including a reduction in incidence of colon cancer and the minimization of lactose intolerance. |
True |
In all cases, it is necessary for disease causing microorganisms to grow in a food to result in a disease transmission to humans. |
False |
Mold-lactic fermentation results in a unique fermented milk consumed in Finland and called |
Viili |
Sequential growth of microorganisms in which the growth of one organism produces environmental conditions for the subsequent growth of another organism is called |
Succession |
In breadmaking, yeast growth is usually carried out under _____ conditions which results in more carbon dioxide production and less alcohol accumulation. |
Oxid |
Which of the following microbial genera is used in the production of fermented dairy products? |
All of the choices (streptococcus, lactobacillus, and leuconostoc) |
The holes in swiss cheese are produced by the metabolic activities of which bacterial genus? |
Propionibacterium |
The science of wine production is called |
Enology |
A major cyanobacterial food source used in many parts of the world is |
Spirulina |
Feeding chickens a strain of Bacillus subtilis leads to |
Increased body weight and feed conversion and a reduction in coliforms and Campylobacter in the processed carcasses. |
When Lactobacillus acidophilus are sprayed on feed, the cattle that eat it appear to have markedly lower carriage of the pathogenic E. coli strain O157:H7 |
True |
The approach of using mutagenesis and genetic selection to produce microbes with new degradative capabilities or the ability to produce compounds with new and unique properties is called _____ evolution. |
Directed |
The first penicillin-producing fungus that could be grown in stirred fermenters was |
Penicillium chrysogenum |
In the process of protoplast fusion, cells are grown in a medium that contains |
Either lysozyme or chitinase, depending on the type of cells |
The medium used in protoplast fusion experiments is |
Isotonic |
A major advantage of protoplast fusion is the fact that |
Protoplasts of different microbial species can be fused |
Primary metabolites |
Are compounds needed for the synthesis of microbial cells in the primary growth phase |
To assure maximum production of desired metabolites, it is always necessary to maintain organisms in active logarithmic growth. |
False |
Molecules produced by a cell that are not directly related to the synthesis of cell materials and that are usually produced after the growth phase has ended are called ______ ______ |
Secondary metabolites |
To industrial microbiologists, fermentation means the mass culture of microorganisms. |
True |
Stirred _______ can range in size from 3 liters to 100,000 liters or larger, depending on production requirements. |
Fermenters |
Frequently a critical component in the medium, often the carbon source, is added ______ so that the microorganisms will not have excess substrate available at any given time. |
Continuously |
Corynebacterium glutamicum is used for the large scale industrial production of |
Amino acids |
Penicillin is produced by some |
Fungi |
Production of semisynthetic penicillins involves chemical modification of a penicillin product after it has been released from penicillin producing cells. |
True |
Although a small fraction of the citric acid used in the food and beverage industry is produced by microbial fermentation, most industrially used citric acid is derived directly from citrus fruit. |
False |
Microbially produced glycolipid surfactants are used for |
Both emulsification and increasing detergency and solubilization of hydrophobic compounds. |
Which of the following is a reason why bioconversions are replacing chemical synthesis of certain compounds? |
Bioconversions yield specific and biologically active stereoisomers |
Most biopolymers industrially produced by means of microorganisms are |
Polysaccharides |
Most antibiotics are produced by |
Actinomycetes |
The major organism used in the microbial production of citric acid is |
Aspergillus niger |
An amino acid that is used as a supplement for breads is |
Lysine |
Corynebacterium glutamicum is used to produce glutamic acid, and this is most successful when the cell permeability is |
Increased |
Phenylacetic acid is added to the penicillin fermentation to allow incorporation of which side chain group? |
Benzyl |
The _____ lactose is often used as a substrate for penicillin production. |
Disaccharide |
A major organism used in the biocontrol of a variety of types of insects is |
Bacillus thuringiensis |
A plasmid from the plant pathogenic bacterium _____ ______ is chiefly responsible for the successful genetic engineering of plants. |
Agrobacterium tumefaciens |
The Ti plasmid has been genetically engineered to improve its utility as a cloning vector by all of the following except |
Genes responsible for resisting infection with B. Thuringeiensis have been added |
Biosensors involve linking which of the following with electronic circuitry? |
Both microorganisms and microbially derived enzymes |
Diatom shell,s when incubated at 900 degrees C in an atomosphere of silicon for several hours, undergo an atom-for-atom substitution of magnesium with silicon without loss of three dimensional structure. |
False |
______ are formed by certain bacteria that convert iron to magnetite; these structures are of interest to _______ because they are despite the fact that they are perfectly formed despite the fact they are ony tens of nanometers in diameter. |
Magnetosomes; nanotechnologists |
In many ways, _____ as a biofuel compares very favorably to ethanol and other fuels. |
Hydrogen |
Microorganisms do not generally reproduce sexually; therefore, species are usually defined by pheneotypic and genotypic similarities. |
True |
In an approach called _________ taxonomy, relatedness is determined by a wide range of phenotypic and genotypic information |
Polyphasic |
Serovars are strains of a species that have distinctive antigenic properties |
True |
Microbial species are collections of strains that share many stable properties in common buffer but significantly from other strains |
True |
The type strain is a well-characterized strain to which other strains are compared for inclusion in or exclusion from a particular species |
True |
The type strain is the most representative strain of a particular species |
False |
Bacterial strains that are characterized by biochemical differences are called |
Biovars |
rRNA signature sequences can be used to place microorganisms in the correct domain |
True |
The G + C content of a DNA sample can be estimated from its TM of a DNA |
True |
Conjugation is useful for determining relatedness between bacteria at the species level because it never occurs between organisms of different genera |
False |
Phylogenetic trees are usually constructed using either a distance-based (__________) approach, or a characteristic (____________) approach. |
Phenetic, cladistic |
Phylogenetic trees show inferred evolutionary relationships in the form of multiple branching lineages connected by nodes |
True |
Transformation is not useful in determining relatedness between two organism because it frequently crosses genera |
False |
The _________ hypothesis proposes that mitochondria and chloroplasts developed from free-living prokaryotes that invaded a precursor to the eukaryotes and established a stable relationship |
Endosymbiotic |
Chromosomal gene exchange is not useful in classification because prokaryotes do not reproduce sexually |
False |
Extensive horizontal gene transfer between domains greatly simplifies thee construction of phylogenetic trees |
False |
The pace of evolution does not always occur at a constant rate but is periodically interrupted by rapid bursts of speciation; this is known as ___________ ____________ |
Punctuated equilibrium |
Although there are other classification schemes for prokaryotes, the one used in Bergey’s Manual is currently considered by most microbiologists to be the most accurate |
True |
The second edition of Bergey’s manual group pathogenic species together rather than in phylogenetic groups |
False |
The scientific study of organisms with the ultimate goal of characterizing and arranging them in an orderly manner is |
Systematics |
The assignment of names to taxonomic groups is referred to as |
Nomenclature |
The determination of the taxon to which an organism belongs is called |
Identification |
The science dealing with classification is called |
Taxonomy |
The arrangement of organisms into groups is best described as |
Classification |
A classification system based on mutual similarity that involves comparing as many characteristics as possible is called a _________ system |
Phenetic |
A classification system based on evolutionary relationships is called a _______ system |
Phylogenetic |
Which of the following is useful in biological systematics? |
All of the choices (Physiology , Epidemiology, Ecology) |
A general term used to describe groups based on mutual similarity or evolutionary relatedness is |
Taxa |
A population descending from a single organism or pure culture isolate is called a |
Strain |
Which of the following is an example of the use of the binomial system devised by Linnaeus? |
Escherichia coli |
The organisms in which of the following are more closely related? |
Family |
The binomial system of nomenclature assigns each organism a scientific name consisting of |
Genus and species |
The general order of classification below the domain or kingdom level is |
Phyla, class, order, family, genus, species |
Mole percent (G+C) of DNA is useful for determining relatedness at the _______ level |
Genus |
Stable annealing due to hydrogen bonding between DNAs of similar nucleotide sequence from different organisms is referred to as |
Hybridization |
The temperature at which half of the strands of a double-stranded DNA molecule have separated from each other is called that ________ temperature |
Melting |
Which of the following is not true about the G + C content percentages in DNA of organisms? |
Organisms with similar G + C percentages have similar base sequences |
Conserved indels are |
A type of signature sequence particularly useful for phylogenetic analysis |
The analysis of genetic relatedness by observing DNA fragmentation patterns resulting from restriction endonuclease cleavage is referred to as |
Genetic fingerprinting |
An unrooted tree contain four unrelated species can become rooted by adding |
A distantly related outgroup |
Small, random genetic changes that occur over generations is known as |
Anagenesis |
According to genome analysis, a member of the genus _________ is most closely related to the mitochondrion |
Rickettsia |
According to the endosymbiosis hypothesis |
All of the choices (The first endosymbiotic involved an anaerobic bacterium, The first endosymbiont was a fermentative organism, The mitochondrion evolved from the same endosymbiont as the hydrogenosome) |
The ancestors of modern ____________ performed the oxygenic photosynthesis responsible for converting our anoxic planet to an oxygenated one |
Cyanobacteria |
A theoretical concept that issued to understand how and why certain organisms can be sorted into discrete taxonomic group sis known as the |
Species concept |
Which of the following is true about Bergey’s Manual? |
The first edition is mostly phenetic while the second edition is more phylogenetic |
The second edition of Bergey’s Manual classifies bacteria |
Phylogenetically |
What percentage of microbes have been cultured in the laboratory? |
1% |
In the microdroplet culture method, cells from mixed assemblages are encapsulated in a gel matrix. The matrix is then emulsified to generate gel "micropdroplets"; each microdroplet contains a mixture of cells |
False |
A technique used to quantify specific types of microbes in natural samples, enrichment cultures and food or water samples is known as the ________ _________ _______ technique |
Most probable number, MPN |
_________ cultures are pure cultures, consisting of a single species |
Axenic |
The use of modern molecular techniques has provided a mechanisms for growing the microorganisms previously referred to as unculturable |
False |
The discrepancy between the number of microbial cells observed by microscopic examination and the number of colonies that can be cultivated from the same natural sample may be due to |
Nonviable organisms and incorrect culture conditions |
____________ culture techniques are based in the expansion of the microenvironment to allow abundant growth of a microorganism formerly restricted to a small ecological niche |
Enrichment |
The fact that cells of genetically uniform populations do not have similar phenotypic attributes is called _________ heterogenerity |
Population |
Optical tweezers can be used to |
Study nucleic acids recovered from individual cells |
Recent evidence suggests that most microbial communities have many individuals representing at least |
1,000,000,000 |
Determining the functional nature of a microbial community by analysis of bulk DNA samples extracted from environmental samples may be misleading for all of the following reasons except |
DNA is of little use in identifying unknown microbes |
When PCR amplification of SSU (small subunit ribosomal RNA) yields a population of different PCR products of about the same molecular weight, these fragments can be separated for further analysis by |
Denaturing gradient gel electrophoresis |
When doing SSU (small subunit ribosomal RNA) of a mixed population of microbes from an environmental sample, specific _____________ are identified |
Phylotypes |
It is generally agreed that SSU (small subunit ribosomal RNA) analysis is a technique that is well suited to identifying species present in a given community |
True |
Which of the following is microscopy in which the microscope is fitted with light filters that enable the excitation of the specific wavelength? |
Epifluorescence microscopy |
_________ ________ arrays are used to asses the diversity of a microbial population |
Community genome |
When fluorescently labeled oligonucleotides that are known to be specific to the microbe of interest are used to label natural samples, the technique is known as |
Fluorescent in situ hybridization (FISH) |
The fact that certain nucleotide templates are more readily amplified than others is termed |
PCR bias |
Phylogenetic oligonucleotide arrays (POAs) contain rRNA sequences as probes and are used as a means to detect complementary rRNA sequences from the environment |
True |
The level of specific mRNA, and therefore the expression of a given gene in a particular ecosystem, can be evaluated in the environment using situ reverse transcriptase (ISRT)-FISH |
True |
_____________ microbes are used to measure oxygen availability, UV radiation dose, pollutant or toxic chemical effects, and stress |
Reporter |
The goal of ____________ is to identify each protein present in a given microenvironment at the time of sampling |
Metaproteomics |
The reporter gene most commonly used to monitor changes in the physical microenvironment for a single microorganism is the |
Green fluorescence protein gene |
Stable isotope analysis to indicate whether or not certain elements have been processed by an organism is based on the observation that |
Microbes generally prefer using the lighter of two stable isotopes |
In two-dimensional nano-liquid chromatography, a complex mixture of peptides is separated first by charge and then by solubility |
False |
Insects frequently contain bacteria in their cytoplasm, and these bacteria form mutualistic association with their host |
True |
Coral bleaching where the photosynthetic endosymbiont is lost or becomes non-functional can be caused by temperature increases as small as 20 Celsius |
True |
When two different microbes are engaged in a cooperative relationship, they do as well when living separately as they do when living together |
False |
In the host-parasite relationship, it is advantageous for the parasite to disable and kill its host as quickly as possible |
False |
A relationship in which one organism is found on the surface of another is referred to as a(n) __________________ |
Ectosymbiosis |
The specialized structure in a tube worm in which endosymbiotic, chemolithotrophic bacteria live is called a(n) _______________ |
Trophosome |
The term ___________ is used to describe a mutually beneficial association in which the growth of an organism is dependent on one or more growth factors, nutrients or substrates provided by another organism in the same vicinity |
Syntrophism |
An example of microbial ___________ is the ability of Vampirococcus to attach to the outer membrane of its prey and then secrete degradative enzymes that result in the release of the prey’s cytoplasmic contents |
Predation |
_____________ is a beneficial relationship similar to mutualism, in which the relationship is not obligatory |
Cooperation |
A close physical relationship between two different species that may or may not be beneficial is called ______________ |
Symbiosis |
____________________ enzymes catalyze the hydrolysis of beta (1-4) linkages between successive D-glucose residues of cellulose |
Cellulase |
The loss of genetic information no longer needed for an intracellular existence by an obligate parasite is called genomic ____________ |
Reduction |
Any microorganism that spends a portion of its life associated with another organism of a different species is engaged in |
Symbiosis |
Which of the following is not a category of symbiosis? |
Phoresis |
In commensalism |
The host and commensal can be separated and remain viable |
In mutualism |
All of these (The mutualist is dependent on the host, A reciprocal benefit accrues to both partners, The partners will not survive separately in many case) |
Which of the following is not part of the lichen association? |
Brown algae |
In a lichen, the fungal partner |
All of these (Protects the alga from excess light intensities, Provides water and minerals to the alga, Provides a substratum within which the alga grows) |
The reason coral reefs are among the most productive and successful ecosystems is due to |
The coral-dinoflagellate mutualistic relationship |
In the rumen, food is quickly attacked by cellulase |
Enzymes produced by microbes |
In the rumen, the carbohydrate fermentation end products include |
All of these (Acetate, Carbon dioxide, Methane) |
In lichens, the fungi send projections of their hyphae across the algal cell wall in order to obtain nutrients from the photosynthetic partner. These projections are called |
Haustoria |
The ectosymbionts of ruminant animals are useful to their hosts in which of the following ways? |
All of the choices (They digest the cellulose of plant cell walls, They produce most of the vitamins needed by the ruminant, The convert glucose to organic acids) |
A physical relationship where an organism hosts more than one symbiont is known as a |
Consortium |
Buchnera aphidicola provides ________ to its aphid host that are essential to the survival of the insect |
amino acids |
The rickettsial parasite Wolbachia pipientis can |
Sometimes alter the sex of an infected wasp |
Dinoflagellates that exist endosymbiotically within a variety of marine invertebrates are called |
Zooxanthellae |
Mussels and sponges sometimes contain methanotrops as intracellular symbionts because the methanotrophs |
Convert methane to carbohydrate for the use by the host |
Riftia tube worms make a unique kind of hemoglobin to |
All of the choices (Transport oxygen, Transport hydrogen sulfide, To assist in the transport of carbon dioxide) |
When Nitrobacter utilizes nitrite produced from ammonia by Nitrosomonas to obtain energy by converting the nitrite to nitrate, the relationship between the two organisms is |
Commensal |
Methanogens are always engaged in relationships with other microbes because methane production requires |
Interspecies hydrogen transfer |
_________ is a predator that bores a hole through the outer membrane of its gram-negative bacterial prey and then reproduces in the periplasm |
Bdellovibrio |
A unidirectional process where a specific compound released by one organism has a negative effect on another organism is called |
Amensalism |
Pseudonocardia is an organism that is hosted by |
Ants that cultivate fungal gardens |
____________ arises when different microbes within a population or community try to acquire the same resource |
Competition |
Microbes such as Lactobacillus acidophilus colonize the human vagina by fermenting |
Glycogen |
The average adult carriers 10 times more microbial cells (1014) than human cells (average about 1013) |
True |
Microorganisms commonly associated with the human body are traditionally referred to as the |
Normal microbial flora or the normal microbiota |
A __________ is any disease-producing microorganisms |
Pathogen |
A species of bacterium associated with the oil glands of the skin belongs to the genus |
Propionibacterium |
Which of the following would not find in the nasopharynx? |
Branhamella catarrhalis |
Which of following would you expect to find in the tonsilar crypts? |
Micrococcus |
Microbiota of the skin are most likely to be found |
In association with oil and sweat glands |
Under normal circumstances, the microbiota of the skin is kept in check by |
A slightly acidic pH |
The term that refers to these microbes found as symbionts in a short relationship of a nongrowing nature is _____________ |
Transient |
A bacterial genus that is found in large numbers in the intestinal tract of breast-fed infants is |
Bifidobacteria |
Which of the following areas of the human is (are) not normally free of microorganism? |
All of these (The ciliated epithelial cells, Lysozyme in mucus, Phagocytic action of alveolar macrophages) |
Human sweat has antimicrobial activity due to |
Production of an antimicrobial peptide called cathelicidins |
Gram-positive bacteria such as Propionibacterium acnes limit the growth of gram-negative bacteria and some fungi on the human skin by converting secreted ___________ to compounds with antimicrobial activity |
Lipids |
When members of the normal microbiota of the human body become pathogenic and produce disease under certain circumstances, they are referred to as ________________ pathogens |
Opportunistic |
The lower respiratory tract has a normal microbiota |
False |
The lower genitourinary tract is usually free of microorganisms |
False |
The skin surface (epidermis) us a very favorable environment for colonization by microorganisms |
False |
Many anaerobic gram-negative bacteria are normally found in the duodenum |
False |
The oral cavity of humans normally becomes colonized with microorganisms within hours after birth |
True |
The condition in the host that results from pathogenic parasitic organism growing and multiplying within or on the host is called |
An infection |
The final outcome of most host-parasite relationships depends on |
all of the choices (number of organisms present in or on the host, the virulence of the organism, the host’s defenses) |
Which of the following has no effect on the outcome of the host-parasite relationship |
all of these have an effect on the outcome of the host-parasite relationship (the number of parasites on or in the host, the virulence of the parasite, the defenses of the host) |
Any organism that can cause disease in the host after direct interaction is a |
Primary pathogen |
An _______ pathogen can cause disease in a host with impaired resistance |
Opportunistic |
Matching |
Latent —-> Organisms present in tissue for long periods of time Antitoxin —> A neutralizing antibody Opportunistic —> Requires weakened immune system Localized —> Not general infection |
If a symbiont either harms or lives at the expense of another organism, the relationship is called |
Parasitism |
An organism other than a human that is infected with a parasitic organism that can also infect humans is called a(n) ______ host. |
Reservoir |
Which of the following is required of a pathogen to possess in order for it to be successful at causing infectious disease? |
All of the choices |
An inanimate object that may be contaminated with a pathogen is called a |
Formite |
Which of the following is a facultative intracellular pathogen? |
Brucella abortus |
Transfer of pathogens from host to environment and then to another host are said to be transmitted _____. |
Indirectly |
A _______ infection is a disease cause by a parasitic organism that is normally found in animals other than humans. |
Zoonotic |
Matching |
Reservoir —-> site where the pathogen normally resides Formite—-> inanimate objects that may be involved in transmission Opportunistic —-> does not harm a healthy host Nosocomial—> develops during a hospital stay |
Vector-borne transmission can be either external or internal. In internal transmission, the pathogen is carried |
on the body surface of a vector |
Inanimate materials involved in pathogen transmission are called reservoirs |
False |
Bacteria within biofilms exchange |
All the above |
Many types of bacteria are only ________ when dispersing from more stable and heterogenous communities known as biofilms |
Planktonic |
Virulence may be measured experimentally at the host level by the _______ which measures the number of pathogens that kills 50% of an experimental group of hosts within a specified amount of time. |
Lethal dose 50 |
The term ______ refers to the degree or intensity of pathogenicity |
Virulence |
Because LPS is bound to the surface of bacteria, it is called a(n) _______. |
Endotoxin |
A neutralizing antibody against a toxin is called a(n) _______. |
Antitoxin |
Exotoxins can be denatured by iodine to form ______ which are useful in vaccines |
Toxoids |
The capacity of an organism to produce toxin is called ________. |
Toxigenicity |
Many bacteria are pathogenic because they carry large segments of DNA called ______ ______ which were acquired by horizontal gene transfer, and which carry genes responsible for virulence |
Pathogenicity islands |
Once a pathogen has infected the host, _________ is a measure of the pathogen’s ability to spread to adjacent or other tissues |
Invasiveness |
While exotoxin production is most generally associated with gram-positive bacteria, some Gram-negative bacteria also produce exotoxins |
True |
Macrophages are phagocytic cells |
True |
Fever responses can be triggered by an endogenous pyrogen called intereleukin-1 |
True |
Colonization specifically refers to the multiplication of a pathogen on or within a host, and includes the resulting tissue invasion and damage |
False |
Generally, exotoxins tend to be more heat stable than endotoxins |
False |
The only organisms to produce endotoxins are gram-negative bacteria |
True |
Listeria monocytogenes propels itself through mammalian host cells using |
Host cells actin and other cytoskeletal proteins |
The toxic component of lipopolysaccharide is called |
Lipid A |
The characteristics of a pathogen that determine its virulence include which of the following |
All of the choices (pathogenicity, invasiveness, and infectivity) |
Pathogenicity islands are typically associated with |
Genes encoding tRNA |
Which of the following is not a biological effect associated with endotoxin |
Paralysis |
Endotoxin is released when |
Gram negative pathogens lyse or divide |
Which of the following is not a characteristic of Lipid A |
Neurotoxic |
Endotoxins include which of the following? |
Lipopolysaccharide |
MCB 3023 Final
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