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Posted by Jim True on April 25, 2003 3:08 AM. Last Updated October 22, 2006 9:23 PM

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07-11 Review Questions

Correct answers are noted in bold.

Chapter 7 - The Microscope

A microscope use a combination of lenses to magnify an image.
A type of image that cannot be viewed directly is called a virtual image.
A compound microscope consists of two lenses mounted at each end of a hollow tube.
The lens closest to the specimen is called the objective lens.
The lens nearest the viewer's eye is called the eyepiece or ocular lens.
The image seen through a compound microscope is virtual.
The coarse and fine adjustments are part of the microscope's mechanical system.True
A transparent specimen is viewed through a microscope using transmitted light.
An opaque object requires a vertical or reflected illumination for viewing with a microscope.
A condenser collects light rays from the base illuminator and concentrates them on the specimen.
A microscope that remains in focus regardless of which objective lens is rotated into place is parfocal.
A microscope having only one eyepiece is monocular; one having two eyepieces is binocular.
Each microscope lens is inscribed with a number signifying its magnifying power.
An eyepiece lens of 10x used in combination with an objective lens of 20x will have a total magnification power of 200x.
The ability of an objective lens to resolve details into separate images is directly proportional to its numerical aperture.
The size of the specimen area in view is known as the field of view.
As magnification increases, the field of view decreases.
The thickness of a specimen in view is known as the depth of focus.
The depth of focus decreases with increasing magnification.
A side-by-side view of two specimens is best obtained with the comparison microscope.
A bridge is used to join two independent objective lenses into a single binocular unit to form a comparison microscope. True
Two monocular compound microscopes properly spaced and aligned describe the stereoscopic microscope.
The stereoscopic microscope is the least frequently used microscope in a typical crime laboratory. False
The stereoscopic microscope offer a large working distance between the objective lens and the specimen.
Light confined to a single plane of vibration is said to be plane polarized.
If a polarizer and analyzer are placed perpendicular to each other, no light will penetrate.
The polarizing microscope allow a viewer to detect polarized light.
Crystals that are birefrigent will produce two planes of polarized light, each perpendicular to the other.
By using the microspectrophotometer, one can view a particle under a microscope while at the same time a beam of light is directed at the particle in order to obtain its absorption spectrum.
The scanning electron microscope focuses a beam of electrons on a specimen to produce an image.
When a beam of electrons strikes a specimen, X-Rays are emitted whose energies correspond to elements present in the specimen.

Chapter 8 - Hair, Fibers, and Paint

Hair is an appendange of the skin, growing out of an organ known as the hair follicle.
The three layers that comprise the hair shaft are cuticle, cortex and medulla.
The scales of most animal hairs can be described as having the appearance of shingles on a roof. True
The cortex contains the pigment granules that impart color to hair.
The central canal running through many hairs is known as the medulla.
The diameter of the medulla relative to the diameter of the hair shaft is the medullary index.
Human hair generally has a medullary index of less than 1/3; the hair of most animals has an index of 1/2 or greater.
Human head hairs generally exhibit absent medullae.
If a medulla exhibits a patterned shape, the hair is animal in origin.
The three stages of hair growth are the anagen, catagen, and telogen phases.
A single hair cannot be individualized to one person by microscope examination.
In making hair comparisons, it is best to view the hairs side by side under a comparison microscope.
Pubic hairs are short and curly, with wide variation in shaft diameter.
It is possible to determine the time when hair was last bleached or dyed.
The age and sex of hair can be determined through an examination of its morphological features. False
Hair forcibly removed from the body often has follicular tissue adhering to its root.
Currently, it is possible for DNA typing to provide for the near individualization of a single hair. True
A anagen hair root is a likely candidate for DNA typing.
A minimum collection of 50 full-length hairs will normally ensure a representative sampling of head hair.
A minimum collection of 24 full-length pubic hairs is recommended to cover the range of characteristics present in this region of the body.
Natural fibers are derived totally from animal or plant sources.
The most prevalent natural plant fiber is cotton.
Regenerated fibers, such as rayon and acetate, are manufactured by chemically treating cellulose and passing it through a spinneret. True
Fibers manufactured solely from synthetic chemicals are classified as synthetic fibers.
Polyester was the first synthetic fiber. False
Polymers are composed of a large number of atoms arranged in repeating units.
The basic unit of the polymer is called the monomer.
Proteins are polymers composed of thousands of amino acids linked together in highly organized arrangement and sequence.
A first step in the forensic examination of fibers will be the comparison of color and diameter. True
The microspectrophotometer employing visible light is a convenient way for analysts to compare the colors of fibers through spectral patterns.
The dye components removed from fibers can be separated and compared by thin layer chromatograhy.
Synthetic fibers possess the physical property of birefringence because they are crystalline.
The microspectrophotometer employing infrared light provides a rapid and reliable method for identifying the generic class of a single fiber.
Normally, fibers possess class characteristics.
The two most important components of dried paint from the criminalist's point of view are the color and the layer structure.
The most important physical property of paint relating to a forensic comparison is layer structure.
Paints can be individualized to a single source only when they have a sufficiently detailed layer structure.
The electrocoat primer layer provides corrosion resistance for the automobile.
“Eye appeal” of the automobile comes from the colorcoat or basecoat layer.
Pyrolysis gas chromatography is a particularly valuable technique for characterizing paint's binder pigments.
Emission spectroscopy can be used to identify the inorganic components of paint's pigments.
Paint samples removed for examination must always include all the paint layers. True

Chapter 9 - Drugs

Underlying emotional factors are the primary motives leading to the repeated use of a drug. True
Drugs such as alcohol, heroin, amphetamines, barbiturates, and cocaine can lead to a high degree of psychological dependence with repeated use.
The development of physical dependence on a drug is shown by withdrawal symptoms such as convulsions when the user stops taking the drug.
Abuse of barbiturates can lead to physical dependency. True
The repeated use of LSD will lead to physical dependency. False
Physical dependency develops only when the drug user adheres to a regular schedule of drug intake.
Narcotic drugs are analgesics that exert a depressive action on the central nervous system.
Opium is a gummy, milky juice exuded through a cut made in the unripe pod of the opium poppy.
The primary constituent of opium is morphine.
Heroin is a chemical derivative of morphine made by reacting morphine with acetic anhydride.
Methadone is classified as a narcotic drug, even though it is not derived from opium or morphine. True
Drugs that cause marked alterations in normal though processes, perceptions, and mood are called hallucinogens.
Hashish is the sticky resin extracted from the marijuana plant.
The active ingredient of marijuana largely responsible for its hallucinogenic properties is tetrahydrocannabinol (THC).
The potency of a marijuana preparation depends on the proportion of the various plant parts in the mixture. True
A marijuana preparation having the highest THC content is liquid hashish.
LSD is a chemical derivative of lysergic acid, the chemical obtained from the ergot fungus that grows on certain grasses and grains.
The drug phencyclidine is often manufactured for the illicit market in clandestine laboratories.
Alcohol depresses the central nervous system.
Barbiturates are called “downers” because they depress the actions of the central nervous system.
Phenobarbital is an example of a long-acting barbiturate.
Methaqualone or Quaalude is a powerful sedative and muscle relaxant that possesses many of the depressant properties of barbiturates.
Tranquilizers are drugs used for the relief of anxiety and tension without inducing sleep.
Glue sniffing stimulates the central nervous system. False
Amphetamines are a group of synthetic drugs that stimulate the central nervous system.
The most severe form of amphetamine abuse stems from its intravenous administration.
An increasing percentage of amphetamines available on the illicit market originate from clandestine drug laboratories.
Cocaine is extracted from the leaf of the coca plant.
Traditionally, cocaine is sniffed into the nostrils.
Cocaine is a powerful central nervous system depressant. False
Anabolic steroids are designed to promote muscle growth but have harmful side effects.
The federal drug control law is known as Controlled Substance Act.
Federal law establishes five schedules of classification for the control of dangerous drugs.
Drugs that have no accepted medical use are placed in schedule One I.
Librium and Valium are listed in schedule Four IV.
Color tests are used to identify drugs conclusively. False
The Marquis color test turns purple in the presence of heroin.
The Marquis color test turns orange-brown in the presence of amphetamines.
The Duquenois-Levine test is a valuable color test for marijuana.
The Scott test is a widely used color test for cocaine.
Microcrystalline tests tentaively identify drugs by the size and shape of crystals formed when the drug is mixed with specific reagents.
Chromatography provides a means of separating drugs from their diluents while making a tentative identification.
The pattern of an infrared absorption spectrum is unique for each drug and thus is a specific test for identification.
The gas chromatograph, in combination with the mass spectrometer, can separate the components of a drug mixture and then unequivocally identify each substance present in the mixture.
The microscopic identification of marijuana largely depends on observing short hairs on the leaf known as cystolitic hairs.
All packages containing drugs must be marked for identification by the police officer before being sent to the laboratory in order to maintain the chain of custody.

Chapter 10 - Forensic Toxicology

The most heavily abused drug in the Western world is ethyl alcohol.
Toxicologists are employed only by crime laboratories. False
The amount of alcohol present in the blood is directly proportional to the concentration of alcohol in the brain.
Blood levels have become the accepted standard for relating alcohol intake to its effect on the body. True
Alcohol consumed on an empty stomach is absorbed faster than an equivalent amount of alcohol taken when there is food in the stomach.
Under normal drinking conditions, alcohol concentration in the blood peaks in 30 to 90 minutes.
In the postabsorption period, alcohol is distributed uniformly among the watery portions of the body.
Elimination of alcohol from the body is accomplished by oxidation and excretion.
Ninety-five to 98 percent of the alcohol is oxidized to carbon dioxide and water.
The oxidation of alcohol takes place almost entirely in the stomach.
The amount of alcohol exhaled in the breath is directly proportional to the concentration of the alcohol in the blood.
Alcohol is eliminated from the blood at an average rate of 0.015 percent w/v.
Alcohol is absorbed into the blood from the stomach and small intestine.
An artery carries blood away from the heart; a vein carries blood back to the heart.
The pulmonary artery carries deoxygenated blood from the heart to the lungs.
Alcohol passes from the blood capillaries into the alveoli sacs located in the lungs.
One milliliter of blood will contain the same amount of alchohol as approximately 2100 milliliters of alveolar breath.
During the period when alcohol is being absorbed into the blood, the alcohol concentration in venous blood will be lower than that in arterial blood.
In a Breathalyzer ampoule, the ethyl alcohol reacts with potassium dichromate in a fixed ratio.
The Breathalyzer measures the absorption of light by potassium dichromate before and after its reaction with alcohol.
Silver nitrate is present in a Breathalyzer ampoule as a catalyst to speed up the rate of reaction.
Alcohol can be separated from other volatiles present in blood and can be quantitated by the technique of gas chromatography.
Breath testers that operate on the principle of infrared light absorption of alcohol are becoming increasingly popular with the law enforcement community.
Portable, handheld, roadside breath testers for alcohol provide evidential test results. False
Usually, when a person's blood-alcohol concentration is in the range of 0.10 percent, horizontal gaze nystagmus will begin before the eyeball has moved 45 degrees to the side.
When drawing blood for alcohol testing, the suspect's skin must first be wiped with a nonalcoholic disinfectant.
Failure to add a preservative, such as sodium fluoride, to blood removed from a living person may lead to a(n) decrease in alcohol concentration.
Most states have established 0.10 percent w/v as the impairment limit for blood-alcohol concentration.
In the case of Schmerber vs. California, the Supreme Court ruled that the taking of non-testimonial evidence, such as a blood sample, was not in violation of a suspect's Fifth Amendment rights.
Heroin is changed upon entering the body into morphine.
The body fluids blood and urine are both desirable for the toxicological examination of a living person suspected of being under the influence of a drug.
A large number of drugs can be classified chemically as acids and bases.
Water having a pH value greater than 7 is basic.
Barbiturates are classified as acidic drugs.
Drugs are extracted from body fluids and tissues by carefully controlling the pH of the medium in which the sample has been dissolved.
The technique of immunoassay is based on specific drug antibody reactions.
It is essential that both screening and confirmation tests be incorporated into the drug-testing protocol of a toxicology laboratory to ensure the correctness of the laboratory's conclusions.
The gas carbon monoxide will combine with hemoglobin in the blood to form carboxyhemoglobin, thus interfering with the transportation of oxygen in the blood.
The amount of carbon monoxide present in blood is usually expressed as percent saturation.
Blood levels of drugs can alone be used to draw definitive conclusions about the effects of a drug on an individual. False
The interaction of alcohol and barbiturates in the body can produce a synergistic effect.
The level of a drug present in the urine is by itself a poor indicator of how extensively an individual is affected by a drug.
Urine and blood levels are best used by law enforcement authorities and the courts to corroborate other investigative and medical findings pertaining to an individual's condition.
The Drug Recognition Expert program incorporates standardized methods for examining suspects to determine if they have taken one or more drugs.

Chapter 11 - Forensic Aspects of Arson & Explosion Investigations

The absence of chemical residues always rules out the possibility of arson. False
The combination of oxygen with other substances to produce new chemical products is called oxidation.
All oxidation reactions produce noticeable quantities of heat and light. False
Energy is the capacity for doing work.
Burning methane for the purpose of heating water to produce steam in order to drive a turbine is an example of converting chemical energy to mechanical energy.
The quantity of heat evolved from a chemical reaction arises out of the breaking and formation of chemical bonds.
Molecules must absorb energy to break their bonds and will liberate energy when their bonds are reformed.
All oxidation reactions liberate heat.
Reactions that liberate heat are said to be exothermic.
Excess heat energy liberated by an oxidation reaction is called the heat of combustion.
A chemical reaction in which heat is absorbed from the surroundings is said to be endothermic.
All reactions require an energy input to start them. True
The minimum temperature at which a fuel will burn is known as the ignition temperature.
A fuel will achieve a sufficient reaction rate with oxygen to produce a flame only when it is in the gaseous state.
The lowest temperature at which a liquid fuel will produce enough vapor to burn is the flash point.
Pyrolysis is the chemical breakdown of a solid material to gaseous products.
Glowing combustion or smouldering is a phenomenon in which a fuel will burn without the prescence of a flame.
The rate of a chemical reaction increases as the temperature rises.
Spontaneous combustion describes a fire caused by a natural heat-producing process.
Oxidizing agents supply oxygen to a chemical reaction.
Three ingredients of black powder are potassium nitrate, charcoal, and sulfur.
An immediate search of a fire scene can commence without obtaining a search warrant. True
A search of the fire scene must focus on finding the fire's origin.
The probable origin of a fire will mostly be located closest to the lowest point that shows the most intense characteristics of burning. True
The collection of debris at the origin of a fire should include all porous materials.
Airtight containers must be used to package all materials suspected of containing hydrocarbon residues.
The most sensitive and reliable instrument for detecting and characterizing flammable residues is the gas chromatograph.
The identity of a volatile petroleum residue is determined by the pattern of its gas chromatogram.
The major advantage of using the vapor concentration technique in combination with gas chromatography is its extreme sensitivity for detecting volatile residues from fire-scene evidence. True
If two gasolines compare by gas chromatographic analysis, it can be concluded that they could have come from the same source.
The criminalist cannot identify gasoline residues by brand name.
Rapid combustion accompanied by the creation of large volumes of gases describes an explosion.
Explosives that decompose at relatively slow rates are classified as low explosives.
High explosives detonate almost instantaneously to produce a smashing or shattering effect.
The most widely used low explosives are black powder and smokeless powder.
The low explosive becomes explosive and lethal only when it is confined.
Air and a gaseous fuel will burn when mixed at any concentration range. False
High explosives can be classified either as initiating or non-initiating explosives.
The blasting power of different dynamite strengths is not in direct proportion to the weight percentage of nitroglycerin.
The most common commercial explosives incorporate the chemical ammonium nitrate. True
The most widely used explosive in the military is RDX.
The explosive core in detonating cord is PETN.
A high explosive is normally detonated by an initiating explosive contained within a blasting cap.
An obvious characteristic of a high explosive is the presence of a crater at the origin of the blast.
The single most important step in the detection of explosive residues is the collection of appropriate samples from the the explosion scene.
Unconsumed explosive residues may be detected in the laboratory through a careful microscopic examination of the debris.
Debris recovered from the site of an explosion is routinely rinsed with acetone in an attempt to recover high-explosive residues.
Once collected, the acetone extract is initially analyzed by color tests, thin layer chromatography, and high pressure liquid chromatography.
The technique of infrared spectroscopy produces a unique absorption spectrum for an organic explosive.
The technique of X-Ray diffraction provides a unique diffraction pattern for the identification of inorganic constituents of explosives.

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