Lab Final Flashcards
Objects appear upside down and backwards through a microscope .
true
Use both hands to carry the microscope; keep the instrument upright.
true
The ___________ is a device invented in the seventeenth century for magnifying objects that are too small to be seen with the naked eye.
microscope
To save time, look through the microscope and rapidly bring the objective lens and the specimen together by rotating the coarse-adjustment knob.
false
The microscopists measures ocular micrometer disk divisions with the stage micrometer.
true
When utilizing a stage micrometer scale marked in 0.01 mm, the following formula holds true: (stage divisions/ocular divisions) x (0.01 mm/stage division) = millimeters per ocular division.
true
The ______ _______ gives microscopists a mathematical way of describing the light-gathering ability of a lens system.
numerical apenture
Most modem microscopes are parfocal. This means the microscopist can add infinitely more lens systems for greater magnification and resolution.
false
A compound microscope contains two or more sets of lenses.
true
Always be sure to oil your microscope lenses before returning the instrument to its designated space.
false
The space separating a specimen and the objective lens is called ________ distance
working
The stage micrometer scale is generally ruled to 0.0001 mm.
false
The objective lens is the one nearest the observer’s eye.
false
Immersion oil has nearly the same refractive index as glass.
true
The numerical aperture of an objective lens depends on the size of the cone of light it can receive and also upon the medium in which the lens is suspended.
true
A specimen is normally placed on top of the stage micrometer and measured with the tiny ruler that is etched onto the stage micrometer.
false
Which microscopist showed the mathematical relationship between resolution and the ability of a lens to gather light?
Ernst Abbe
Which microscopist published the first drawings of bacteria in 1676?
Anton van Leeuwenkoek
Lens paper can be used to remove oil from the glass components of the microscope.
true
To calculate the total magnification of your microscope, add the magnifications of the objective and ocular lenses.
false
The area that you see through a lens is the microscopic ________
field
Increasing the size of a blurred image generally reveals further details.
false
If a lens is designed to be used with immersion oil, it is able to gather more light when the oil is utilized than when air separates the lens from the specimen.
true
Resolving power is the ability to rotate a new objective Jens into the observation position and have the field remain in focus.
false
When utilizing a stage micrometer scale marked in 0.01 mm, the following formula holds true: (stage divisions/ocular divisions) x (10 um/stage division) = micrometers per ocular division.
true
Before vortexing bacterial cells in a broth culture, always remove the test tube closure.
false
Coccobacilli are cocci; palisades are groups of four cocci.
false
Smears should be air dried before they are heat fixed.
true
Heat fix bacterial smears by holding the slide in the hottest part of the flame for 2 minutes.
false
The decolorization in the Gram stain is Gram’s iodine.
false
In the Gram stain procedure, what is the color of gram-negative bacteria after the primary stain?
purple
Water rinses should not be left on the smear too long during the gram stain procedure because water slowly decolorizes stained cells.
true
A cation has a positive charge; chromophores are always anions.
false
An aqueous solution is made with water.
true
The primary stain in the Gram stain is crystal violet.
true
The cell wall of a gram-negative bacterium contains lipoprotein and lipopolysaccharide.
true
The peptidoglycan layer of a gram-negative cell wall is thicker than the corresponding layer of a gram-positive cell wall.
false
In the Gram stain procedure, what is the color of gram-positive bacteria after decolorization?
purple
In the neutral environment of most microbiological dyes, bacteria generally carry a net negative charge.
true
Gram-positivity is a characteristic that is easily lost.
true
In the Gram stain procedure, what is the color of gram-negative bacteria after the mordant (iodine)?
purple
Aniline dyes are derived from benzene, a coal tar derivative.
true
The chromophore of a basic dye carries a negative charge.
false
In the Gram stain procedure, what is the color of gram-negative bacteria after the counterstain stain?
pink
The decolorization is applied before the mordant in the Gram stain procedure.
false
The cell wall of gram-positive have a thick layer of peptidoglycan associated with teichoic acids.
true
In the Gram stain procedure, what is the color of gram-positive bacteria after the primary stain?
purple
A slide is clean enough for bacteriological smears if water coalesces on it.
false
A chemosynthetic organism is able to construct cellular molecules out of carbon dioxide and oxygen.
false
Antibiotic sensitivity testing is performed with pure cultures.
true
what is the term for devoid of life
aseptic
what is the term for A combination of various microbial species living together
mixed culture
what is the term for One kind of bacteria, ideally the descendants of one cell, living together
pure culture
what is the term for the introduction of unwanted organisms
contamination
what is the term for free from disease-producing microorganisms
sterile
Many cyanobacteria fix gaseous nitrogen.
true
Sterile techniques are generally utilized with broth cultures; aseptic techniques are reserved for solid media work.
false
Flaming sterilizes by incinerating organisms.
true
Rotifers are protozoa.
false
Endospores are resting or survival structures.
true
Heterotrophic organisms require organic molecules for a carbon source.
true
Aseptic techniques are performed only for their traditional value. In a modem microbiology laboratory, microbes are electronically removed from the air, workbench, inoculation instruments, and hands.
false
Microbiology laboratories often maintain stock cultures. These stocks are pure cultures.
true
Unstained Treponema pallidum is too thin to be observed with a compound, light, bright-field microscope.
true
In a microbiology laboratory, it is generally safe to mouth pipet since most microorganisms are not killed by exposure to exhaled air.
false
A photosynthetic organism is able to make cellular energy out of light energy.
true
Alcohol-flaming can be employed to sterilize the tips of forceps.
true
An aerosol is a visible clump of bacteria suspended in proteinaceous matter such as sputum.
false
When transferring bacteria from a solid surface, be sure to gouge the agar, digging out the entire colony where it has burrowed into the medium.
false
To help identify a bacterial species, a microbiologist usually performs biochemical tests on the mixed culture.
false
Factors that limit the amount of growth in a broth culture include size of inoculum, availability of nutrients, temperature and duration of incubation, presence of oxygen, concentration of toxins, and so on.
true
Some rods are called diphtheroids because they resemble Corynebacterium diphtheriae.
true
Select organisms with a eukaryotic cell or cells. (3)
Bacteria (including cyanobacteria)
protozoa
multicellular invertebrates
algae
algae
protozoa
multicellular invertebrates
which group contains endospores
bacteria (including cyanobacteria)
Bacteria moving toward oxygen are displaying negative phototaxis.
false
To focus on unstained, transparent cells, reduce illumination of the field far below the levels used with stained cells.
true
A saprophytic organism usually parasitizes living tissue, causing disease and death.
false
what has a prokaryotic cell
bacteria
Alcohol-flaming should always be performed over a stack of papers so that the dripping alcohol does not burn the workbench.
false
Daphnia is an alga.
false
During alcohol-flaming, the tips of the forceps are not held in the burner flame until they are red-hot.
true
In nature most microorganisms are found in mixed cultures.
true
Spirochetes are rigid, inflexible, spiral-shaped bacteria; spirilla are flexible, spiral-shaped bacteria.
false
If an organism lacks a nuclear membrane but is green and produces oxygen, it is probably a member of which group?
bacteria
To preserve purity, handle cultures as little as possible. Open them all at the beginning of the laboratory period; close them once, before leaving the area.
false
Inoculating needles and loops are generally constructed of Nichrome or platinum wire.
true
Worms are multicellular invertebrates.
true
Pairs of cocci are called packets.
false
The energy of life produces order and dispels entropy.
true
In a pour plate, colonies develop throughout the medium.
true
Colonies are smaller in crowded areas of a pour plate than in areas where they are well separated.
true
Lenticulate colonies are usually found on the surface of a pour plate.
false
In microbiology laboratories, colonies are usually counted to determine the number of bacteria per milliliter of the original sample.
true
A countable plate has between 1 and 300 colonies.
false
The physiological characteristics of an organism are its Gram stain reaction.
false
In a serial dilution, each tube contains the same dilution as the previous one.
false
To fulfill Koch’s postulates, a researcher must cultivate a mixed culture of organisms from the blood of a diseased experimental animal.
false
Koch’s postulates are used to prove that a specific microorganism causes a specific disease.
true
Robert Koch was a pioneer of medical microbiology.
true
In a sample of human sputum or feces, you usually find a mixture of many different kinds of organisms.
true
In samples from nature, bacteria are usually found in mixed culture.
true
The two most common methods that separate individual bacteria from each other are the pour plates and lawns.
false
Be sure to flame your swab after preparing a spread plate.
false
Bacterial sensitivity to antibiotics is often tested on a spread plate.
true
Bacteriophage are special bacteria that are grown in spread plates.
false
All bacterial colonies look alike. Only staining reveals differences between genera.
false
The area of confluent growth is where colonies overlap and grow together.
true
The progeny of a single cell may form a colony, a visible clump of growth, on the surface of an agar medium.
true
Streaking a plate involves drawing a loopful of organisms back and forth across a solid medium in a Petri dish until the microbes fall off the loop one at a time.
true
A bacterial concentration gradient is a well-dispersed mixture of bacteria, thoroughly suspended in a broth culture.
false
When preparing a bacterial spread plate, swab a pure culture of bacteria evenly over the entire surface of an agar medium in a Petri dish.
true
To prepare a streak plate, spread bacteria evenly over the entire surface of a plate of medium.
false
Neisseria gonorrhoeae and Haemophilus influenzae are generally incubated in a candle jar.
true
Host-specific phages can distinguish one strain of a single bacterial species from another strain of the same species.
true
Bacteria are used to treat virus strains (with ice packs and tiny Ace bandages) in bacteriophage typing.
false
Since there is oxygen in the air that surrounds earth, being an aerobe is a great advantage for microorganisms in nature.
false
In a broth-clearing assay, the titer of phage in the original coliphage sample equals the end-point tube’s dilution.
false
A plaque assay is designed to discover the number of bacteria in a viral solution.
false
Loosen the caps of screw cap tubes before incubating oxygen-utilizing bacteria in them.
true
After inoculating a tube of Fluid Thioglycollate Medium, shake the tube thoroughly to aerate and separate the bacteria.
false
Fermentation does not require oxygen.
true
Cultivation of viruses in tissue culture is generally as quick, inexpensive, and convenient as growing bacteria in nutrient media.
false
Viruses are classified by host, nucleic acid, size, shape, and presence or absence of an envelope.
true
The enzyme that catalyzes the reaction 2H2O2 -> 2H2 + O2 is superoxide dismutase.
false
Fermentation releases some but not all of the energy in organic compounds.
true
Coliphage are common microbiological laboratory “weeds” that infect all human pathogens.
false
The titer (concentration) of virions in your original coliphage sample equals the number of plaques on a countable plate times the inverse of that plate’s dilution.
true
To prepare an agar shake culture, boil the medium, solidify it, and then inoculate it with a clean stab to the bottom of the tube.
false
After incubation, the sealed redox potential indicator envelope is removed from a GasPak jar and opened.
false
A redox potential is the opposite of an oxidation reduction potential; when one is high the other is low.
false
To prepare a coliphage plaque assay, add Escherichia coli strain B to Soft Agar overlays, add dilutions of a virulent coliphage, pour the overlays into Tryptic Soy Agar in Petri dishes, incubate appropriately, then examine for liquefaction of the Soft Agar.
false
A candle jar contains the best mix of gases available for culturing anaerobes.
false
Pasteur discovered anaerobes, microorganisms that are poisoned by oxygen.
true
A plaque-forming unit represents one bacterial cell.
false
Fluid Thioglycollate Medium is pink in the bottom of the tube where the resazurin is highly reduced.
false
Viruses are defined as “cellular” because they replicate inside of living host cells.
false
Bacteria that are exposed to air as they grow are generally in a highly reduced envrionment.
false
Spread a thick layer of petroleum jelly around the O-ring of a GasPak jar before sealing the lid.
false
A viral plaque is a hole in a confluent layer of permissive host cells.
true
Anaerobes grow in reduced environments.
true
If nitrite is missing from an incubated culture tube of Nitrate Broth, it may indicate that the bacteria did not produce nitrate reductase.
true
Proteus is urease-positive; Salmonella and Shigella are urease-negative.
true
Denitrification is the complete oxidation of NO-3 to form nitrogen gas.
false
Facultatively anaerobic bacteria generally do not produce nitrate reductase.
false
Endoenzumes speed reactions outside of cells.
false
Urease catalyzes the reduction of NO-3; nitrate reductase catalyzes the hydrolysis of NO-2.
false
Probes are pieces of nucleic acid that scientists sometimes use to identify microbes.
true
Proteus is generally nonpathogenic in the human intestine, but it is a common cause of urinary tract infections.
true
On Starch Agar a darkened area indicates starch hydrolysis.
false
Cytochrome oxidase is produced by Pseudomonas but not by members of the Enterobacteriaceae.
true
Egg yolk contains the phospholipid lecithin (choline phosphoglyceride), an emulsifying agent. About two-thirds of the dry weight of egg yolks is lipid.
true
To analyze the reactions of bacteria growing on Starch Agar, flood the plate with 3% hydrogen peroxide.
false
Any bacteria that grow on a plate of Starch Agar are amylase producers.
false
An oxidase is an enzyme that oxidizes compounds.
false
Enterococcus, Streptococcus, and Lactobacillus tolerate oxygen and produce catalase.
false
Gelatin suspensions are in the gel state below 25 degrees C.
true
In a Nitrate Broth culture, if zinc reduces nitrate to nitrite, then the bacteria in the tube did not.
true
All bacteria that utilize desulfhydrases produce hydrogen sulfide, rotten egg gas.
true
Catalase helps Staphylococcus aureus poison mayonnaise by attacking fat molecules.
false
Cysteine desulfhydrase yields hydrogen sulfide, hydrochloric acid, and pyruvic acid.
false
Hydrogen peroxide is toxic to cells, but it is also a common by-product of reactions that accompany aerobic respiration.
true
Some exoenzymes break down molecules that are too large to cross a cell membrane.
true
Urea is a protein.
false
Amylases hydrolyze starch by adding the Na+ and CI- ions of H2O.
false
Lipids are found in all cell membranes.
true
Along with other information, DNA carries the genetic code for all the enzymes that a microorganism produces.
true
Starch is a large, many-branched polymer of the monosaccharide glucose.
true
Urea is toxic to most cells, but urease producers can degrade this nitrogen-containing compound.
true
Microbial physiology is the study of the size, shape, arrangement, and staining reactions of bacteria.
false
The black precipitate that may form in a test tube containing Triple Sugar Iron Agar consists of H2S.
false
Clostridium tetani toxin kills with the rigid paralysis of tetanus.
true
Since agar media are largely water, a water-soluble microbial pigment tints the agar as well as the colony.
true
The most deadly biological nerve toxin known is botulism toxin.
true
A colony is an individual bacterial cell.
false
All endospores are terminally located in swollen sporangia.
false
Endospore-forming bacteria produce the ____________________ antibiotics that inhibit cell wall synthesis.
bacitracin
Conditions of incubation include temperature, pH, and salinity, but not the medium and its nutrients.
false
The Schaeffer-Fulton endospore-staining procedure employs ethyl alcohol and phenol to drive malachite green into endospores.
false
After staining with the Schaeffer-Fulton endospore procedure, endospores appear pickle green while vegetative cells are periwinkle blue.
false
Endospores preserve life in a/an __________
state with no measurable metabolic activity.
cryptobiotic
Bacillus anthracis is the etiologic agent of anthrax.
true
When the scientific method of investigation is employed, only experiments that prove the accuracy of the original hypothesis are useful.
false
Opaque means translucent.
false
A control is a test in which only one factor is different than in the experiment.
true
Endospores in cooked food may germinate at room temperatures and lead to food poisoning.
true
Bacterial endospores are hard, dry structures that burst forth as external buds on certain genera of flowering rods.
false
The appearance of a colony reflects the biochemistry of the species that formed it, so all bacterial colonies look alike.
false
Which is the decolorizer in the Schaeffer-Fulton endospore-staining procedure?
water
Which is the primary dye used in the Schaeffer-Fulton endospore-staining procedure?
malachite green
In the Schaeffer-Fulton endospore stain, which of these is the counterstain?
safranin
Which of these is a common aniline dye used by microbiologists but not employed in the Schaeffer-Fulton endospore-staining procedure?
methylene blue
When utilizing the scientific method of investigation, you must first recognize a problem or situation and then gather information concerning it.
true
Scrubbing the hands with antiseptic solution and a brush for 40 seconds always kills all bacteria on the cleansed area.
false
Soap cleans by chemically linking oil to grease.
false
Soaps are formed when fats are heated in the presence of an acid such as hydrochloric acid.
false
The carboxylate end of a soap molecule is soluble in the hydrocarbons, the oily end in water.
false
Washing hands usually reduces their microbial load of transient flora.
true
Any cleansing solution, including soap, is a detergent.
true
If 38 colonies develop on a 10-6 dilution plate, it seems likely that between 0 and 5 colonies might grow on a 10-5 plate prepared from the same original suspension of bacteria.
false
Thoroughly scrubbing the hands and fingernails with hot soapy water for 1 minute removes all bacteria from the area cleansed.
false
Filtration and cultivation of colonies on a filter will determine __________________________The measurement of optical density will measure ___________________ Spread plate colony count is used for ____________________
Fit 1 from either: quantification of viable microorganisms only. Quantification of both viable and nonliving microorganisms.
Filtration and cultivation of colonies on a filter will determine quantification of viable microorganisms only.
. The measurement of optical density will measure
quantification of both viable and nonliving microorganisms.
. Spread plate colony count is used for
quantification of viable microorganisms only.
Soap forms a chemical link between oil and water.
true
Only a living colony-forming unit forms a colony.
true
Hand washing by medical personnel helps reduce the patient’s risk of nosocomial (hospital-acquired) infections.
true
A colony-forming unit may be a single cell or a clumps of bacteria.
true
During saponification a sodium salt of an acid is produced
true
The soapy scum that forms in oily, hard water removes bacteria when it sinks to the bottom of the liquid, weighted down by its load of heavy mineral salts.
false
If you pour 15 ml of agar medium into a Petri dish that contains 1 ml of a 10-6 bacterial dilution, the dilution of the plate is still recorded as 10-6.
true
Saponification is a highly complex chemical process, but soap making is fairly straightforward.
false
Estimation of microbial population size are useful for industrial microbiologist but are of little value to the medical or public health microbiologist.
false
