Microbiology MCB3023 Exam 4 – Flashcards

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 lower carriage of the pathogenic E. coli strain O157:H7 a reduction in coliforms and Campylobacter in the processed carcasses all of the choices increased body weight and feed conversion

Which of the following determines whether or not a wine is considered to be dry? The amount of free sugar after fermentation The type of grape used as a starting material The amount of carbon dioxide after fermentation The percentage of alcohol after fermentation

The process of beer lagering involves none of the choices carbonation distillation aging

Bread products can be spoiled by the growth of Bacillus species that produce ropiness sourdough bread gassy doughs nonrising breads

The conventional low-temperature holding procedure used in the pasteurization of milk involves holding the milk at 62.8 °C for __________ minutes. 15 5 60 30

A major advantage of protoplast fusion is the fact that the microbes are rendered harmless by the process the protoplast condition can easily be maintained indefinitely all of the choices protoplasts of different microbial species can be fused

Most biopolymers industrially produced by means of microorganisms are cell wall constituents polysaccharides nucleic acids histones

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. sporadically none of the choices continuously gradually

Most antibiotics are produced by unicellular bacteria actinomycetes protozoa yeasts

The science dealing with classification is called systematics taxonomy nomenclature identification

rRNA signature sequences can be used to place microorganisms in the correct domain. True False

A general term used to describe groups based on mutual similarity or evolutionary relatedness is system class taxa group

The determination of the taxon to which an organism belongs is called identification systematics taxonomy classification

Microbial species are collections of strains that share many stable properties in common but differ significantly from other strains. True False

The temperature at which half of the strands of a double-stranded DNA molecule have separated from each other is called the __________ temperature. melting mobilization separation destabilizing

Mole percent (G+C) of DNA is useful for determining relatedness at the __________ level. none of the choices class kingdom genus

Which of the following is not true about the G + C content percentages in DNA of organisms? Organisms with different G + C percentages have dissimilar base sequences. Organisms with similar G + C percentages have similar base sequences. Organisms with different G + C percentages have dissimilar base sequences All of these are true about the G + C percentages of organisms.

Chromosomal gene exchange is not useful in classification studies because prokaryotes do not reproduce sexually. True False

The binomial system of nomenclature assigns each organism a scientific name consisting of species and strain genus and species kingdom and species kingdom and genus

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: The DNA obtained can depend on the extraction method used. DNA is of little use in identifying unknown microbes. Some of the DNA recovered may be from non-living organisms. Some of the DNA may be from non-functional entities such as spores.

The reporter gene most commonly used to monitor changes in the physical microenvironment for a single microorganism is the RecA protein gene. luciferase gene. beta-galactosidase gene. green fluorescence protein gene.

What percentage of microbes have been cultured in the laboratory? 20% 30% 1% 10%

In mutualism all of these the partners will not survive separately in many cases. the mutualist is dependent on the host. a reciprocal benefit accrues to both partners.

The ectosymbionts of ruminant animals are useful to their hosts in which of the following ways? all of the choices They convert glucose to organic acids. They produce most of the vitamins needed by the ruminant. They digest the cellulose of plant cell walls.

Escherichia coli is the most prevalent bacterium found in the colon. True False

Reservoir

Fomite

Opportunisitic (parasite)

Nosocomial

The final outcome of most host-parasite relationships depends on all of the choices the host's defenses. the virulence of the organism. the number of organisms present in or on the host.

An organism other than a human that is infected with a parasitic organism that can also infect humans is called a(n) ________ host. intermediate. endoparasite. transfer. reservoir.

Pathogenicity islands are typically associated with none of the choices genes encoding rRNA. genes encoding tRNA. G+C content similar to the rest of the bacterial genome.

Nisin all of the choices is a small amphiphilic 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.

Pasteurization of milk is no longer used for food processing in the USA usually eliminates all disease-causing organisms is a method for sterilization of food items reduces microbial growth by decreasing availability of water

Temperature and relative humidity are important intrinsic factors in determining the rate of food spoilage. True False

To control pathogenic and disease-causing organisms, spices can be fumigated using __________. chlorine gas ammonium gas ethylene oxide heavy metals

Corynebacterium glutamicum is used for the large scale industrial production of vitamin B1 polysaccharides antibiotics amino acids

The first penicillin-producing fungus that could be grown in stirred fermenters was Aspergillus niger Pisolithus tinctorius Penicillium notatum Penicillium chrysogenum

Which of the following can function better at lower pH? yeasts and molds protozoa bacteria viruses

Aflatoxins are planar, ringed compounds that interact with DNA by ___________ and cause frameshift mutations. rearrangement intercalation deletion substitution

Streptococcus thermophilus and Lactobacillus bulgaricus contribute to the flavor of yogurt by producing diacetyl during the fermentation of lactose. True False

To control microbial growth in a food, one can decrease water availability by the addition of sugar or salt. formaldehyde agar gelatin

The science of wine production is called horology eurology rheology enology

In many ways, ______________ as a biofuel compares very favorably to ethanol and other fuels.

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 __________ __________.

Production of semisynthetic penicillins involves chemical modification of a penicillin product after it has been released from penicillin producing cells. True False

Primary metabolites include bacteriocins and other similar cytotoxic compounds. are compounds needed for the synthesis of microbial cells in the primary growth phase. include compounds such as antibiotics and mycotoxins. are compounds that accumulate during the period after primary growth phase and have no direct relationship to the synthesis of cell materials.

The fact that certain nucleotide templates are more readily amplified than others is termed analytical PCR. multiplex PCR. PCR bias. real-time PCR.

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 polymerase chain reaction (FISH). fluorescent in situ hybridization (FISH). epifluorescence microscopy. gel electrophoresis.

In a lichen, the fungal partner provides water and minerals to the alga. provides a substratum within which the alga grows. protects the alga from excess light intensities. all of these

Pseudonocardia is an organism that is hosted by ants that cultivate fungal gardens. wood-eating insects. marine invertebrates. people with severe acne.

In the host-parasite relationship, it is advantageous for the parasite to disable and kill its host as quickly as possible. False True

The toxic component of lipopolysaccharide is called antigen polysaccharide. exotoxin. hemolysin. lipid A.

If a symbiont either harms or lives at the expense of another organism, the relationship is called pathogenicity. symbiosis. commensalisms. parasitism.

Microorganisms do not generally reproduce sexually; therefore, species are usually defined by phenotypic and genotypic similarities. True False

Stable annealing due to hydrogen bonding between DNAs of similar nucleotide sequence from different organisms is referred to as restriction hybridization ligation hydrolysis

A classification system based on mutual similarity that involves comparing as many characteristics as possible is called a __________ system. phylogenetic phyletic determinative systematic phenetic

A theoretical concept that is used to understand how and why certain organisms can be sorted into discrete taxonomic groups is known as the species concept phylogenetic concept genotypic concept endosymbiotic theory

Serovars are strains of a species that have distinctive antigenic properties True False

According to the endosymbiosis hypothesis the first endosymbiont was a fermentative organism all of the choices the first endosymbiotic event involved an anaerobic bacterium the mitochondrion evolved from the same endosymbiont as the hydrogenosome

The general order of classification below the domain or kingdom level is phyla, class, family, order, genus, species phyla, class, order, family, genus, species phyla, order, family, class, genus, species phyla, order, class, family, genus, species

Conjugation is useful for determining relatedness between bacteria at the species level because it never occurs between organisms of different genera. True False

Which of the following is an example of the use of the binomial system devised by Linnaeus? Enterobacteriales O157:H7 Enterobacteriaceae Escherichia coli

The G + C content of a DNA sample can be estimated from its TM of a DNA. True False

A population descending from a single organism or pure culture isolate is called a genus strain species subspecies

Which of the following is useful in biological systematics? epidemiology ecology physiology all of the choices

Transformation is not useful in determining relatedness between two organisms because it frequently crosses genera. True False

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 DNA hybridization. denaturing gradient gel electrophoresis. size exclusion chromatography. isoelectric focusing.

When doing SSU (small subunit ribosomal RNA) of a mixed population of microbes from an environmental sample, specific _____________ are identified. unknown microbes genotypes phylotypes phenotypes

Dinoflagellates that exist endosymbiotically within a variety of marine invertebrates are called endotrophic. endoflagellates. parasites. zooxanthellae.

Under normal circumstances, the microbiota of the skin is kept in check by a high pH (above 8). a slightly acidic pH. excessive moisture. phagocytic activity

Insects frequently contain bacteria in their cytoplasm, and these bacteria form a mutualistic association with their host. True False

Latent

Antitoxin

Opportunistic

Localized

The characteristics of a pathogen that determine its virulence include which of the following? pathogenicity all of the choices infectivity invasiveness

Which of the following has no effect on the outcome of the host-parasite relationship? The virulence of the parasite. The number of parasites on or in the host. The defenses of the host. All of these have an effect on the outcome of the host-parasite relationship.

Bacteria within biofilms exchange plasmids. all of the choices nutrients. quorum-sensing molecules.

The polymerase chain reaction (PCR) can detect as few as 10 toxin-producing Escherichia coli in a population of 100,000 microorganisms isolated from soft cheese samples. True False

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 False

The production of natural carbon dioxide by yeasts after a wine is bottled results in dry wine brandy sweet wine champagne

Penicillin is produced by some fungi bacteria protozoan actinomycetes

A plasmid from the plant pathogenic bacterium ____________ ____________ is chiefly responsible for the successful genetic engineering of plants.

A classification system based on evolutionary relationships is called a __________ system. determinative phenetic phylogenetic systematic

The analysis of genetic relatedness by observing the DNA fragmentation patterns resulting from restriction endonuclease cleavage is referred to as none of the choices genetic patterning genetic restriction genetic fingerprinting

The type strain is a well-characterized strain to which other strains are compared for inclusion in or exclusion from a particular species. True False

Recent evidence suggests that most microbial communities have many individuals representing at least ______ taxa. 1,000 10,000,000 1,000,000,000 100,000

Any microorganism that spends a portion of its life associated with another organism of a different species is engaged in synergy. commensalism. parasitism. symbiosis.

Coral bleaching where the photosynthetic endosymbiont is lost or becomes nonfunctional can be caused by temperature increases as small as 2° C. True False

Any organism that can cause disease in the host after direct interaction is a opportunistic pathogen. focal pathogen. primary pathogen. secondary pathogen.

Ergotism involves microorganism production of sweeteners hallucinogenic alkaloids thermostable enzymes flavoring compounds

Sometimes __________ beams are used to irradiate foods in place of gamma radiation because the process does not generate radioactive waste. electron magnetic none of the choices microwave

Mashing is a process involving carbonation carbohydrate hydrolysis inoculation protein putrefaction

Microbially produced glycolipid surfactants are used for emulsification and increasing detergency, which aids in biodegradability solubilization of hydrophobic compounds, which enhances cleanup and recovery of oil from spills. both emulsification and increasing detergency and prevention or reduction of microbial growth on surfaces. prevention or reduction of microbial growth on surfaces, decreasing transmission of disease. both emulsification and increasing detergency and solubilization of hydrophobic compounds.

The medium used in protoplast fusion experiments is isotonic none of the choices hypertonic hypotonic

An unrooted tree containing four unrelated species can become rooted by adding a descendant related to only one of the species a distantly related outgroup a descendant group related to two of the species an unrelated outgroup

According to genome analysis, a member of the genus ______________ is most closely related to the mitochondrion Rickettsia Prochloron Escherichia Agrobacterium

The scientific study of organisms with the ultimate goal of characterizing and arranging them in an orderly manner is identification systematics classification taxonomy

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 incorrect culture conditions. nonviable organisms and incorrect culture conditions. microbial motility. nonviable organisms.

The fact that cells of genetically uniform population do not have similar phenotypic attributes is called ____________ heterogeneity. epigenetic population dissimilar quorum

A physical relationship where an organism hosts more than one symbiont is known as a partnership. consortium. cojoining. clade.

The oral cavity of humans normally becomes colonized with microorganisms within hours after birth. True False

Which of the following is required of a pathogen to possess in order for it to be successful at causing infectious disease? Be able to exit the host. Ability to adhere to, colonize, or invade the host. Initially be transported to the host. Ability to damage the host. All of the choices.

Vector-borne transmission can be either external or internal. In external (mechanical) transmission, the pathogen is carried within the vector. on a fomite. all of the choices on the body surface of a vector.

Which of the following is true about molecular methods of microorganism detection in foods? All of the choices are correct They can be used to detect slow growing pathogens. They can be used to detect viruses that are not easily cultured. They can be used to detect the presence of a single specific pathogen.

Which of the following helps preserve foods by controlling microbial access to water? drying all of the choices addition of salt addition of sugar

Atmosphere is important in food spoilage; high H S tends to reduce spoilage, while high CO tends to increase spoilage. 2 2 True False

A major organism used in the biocontrol of a variety of types of insects is Clostridium botulinum Bacillus thuringiensis Bacillus cereus Bacillus subtilis

Corynebacterium glutamicum is used to produce glutamic acid, and this is most successful when the cell permeability is decreased isotonic increased not changed

The assignment of names to taxonomic groups is referred to as nomenclature taxonomy systematics identification

Stable isotope analysis to indicate whether or not certain elements have been processed by an organism is based on the observation that none of the choices microbes generally prefer using the heavier of two stable isotopes. microbes generally prefer using the lighter of two stable isotopes. microbes have no preference as regards heavy versus light isotopes.

The goal of __________ is to identify each protein present in a given microenvironment at the time of sampling. metaproteomics metagenomics both metagenomics and metaproteomics none of the choices

A species of bacterium associated with the oil glands of the skin belongs to the genus Staphylococcus. Propionibacterium. Pityrosporum. Pityrosporum.

Which of the following is not a characteristic of lipid A? neurotoxic. weakly immunogenic. heat stable. toxic in nanogram amounts.

The use of plastic film to wrap meat products can result in increased surface growth of microorganisms in part because of exposure to oxygen N2 which comprises approximately 78 % of gas in the atmosphere water carbon dioxide

Pulsedfield gel electrophoresis can be used to link a particular pathogen associated with disease outbreaks in a specific food source. True False

The process of racking, used in the production of wines, involves addition of carbon dioxide addition of sulfites depressurizing bottles removal of sediments

Growth of yeasts and molds will be favored in more acidic foods. True False

When members of the normal microbiota of the human body become pathogenic and produce disease under certain circumstances, they are referred to as ______________ pathogens. conditional occasional opportunistic partial

The average adult carries 10 times more microbial cells (1014) than human cells (average about 1013). False True

A major chemical used to preserve meat products is refrigeration propionate nitrite ethylene oxide

Phenylacetic acid is added to the penicillin fermentation to allow incorporation of which side chain group? propyl benzyl methyl acetyl

Phylogenetic trees show inferred evolutionary relationships in the form of multiple branching lineages connected by nodes. True False

Which of the following is not a category of symbiosis? phoresis mutualism parasitism commensalism

Microbiota of the skin are most likely to be found all of the choices where there is little moisture. in association with oil and sweat glands. where the pH of the skin secretions is below 4

The skin surface (epidermis) is a very favorable environment for colonization by microorganisms. False True

Which of the following is not a biological effect associated with endotoxin? coagulation paralysis fibrinolysis fever

Which of the following is a facultative intracellular pathogen? Rickettsia Viruses All of the choices Brucella abortus

A major fungal genus that produces aflatoxin is Aspergillus Rhizopus Claviceps Claviceps Penicillium

Clostridium botulinum and Bacillus cereus are important disease-causing microorganisms of food which cause infections intoxications birth defects cancers

Which of the following is microscopy in which the microscope is fitted with light filters that enable the excitation of the specimen with a specific wavelength? Bright-field microscopy Epifluorescence microscopy Electron microscopy Dark-field microscopy

In the rumen, food is quickly attacked by cellulase archeons. enzymes produced by both the ruminant and the microbe. enzymes produced by microbes. enzymes produced by the ruminant.

Mussels and sponges sometimes contain methanotrophs as intracellular symbionts because the methanotrophs all of the choices allow the partnership to use hydrogen sulfide as a source of electrons. convert methane to carbohydrate for use by the host. remove otherwise toxic levels of methane from the environment.

Filtration is sometimes used to remove organisms from beer because it has less effect on the flavor than pasteurization. True False

The swelling of a food-containing can is frequently due to the production of ___________ by spoilage microbes. carbon dioxide gas nitrogen gas all of the choices oxygen gas