Forensic Science Chapter 8; Hair, Fibers, and Paint

Hair is an appendage of the skin, growing out of an organ known as the______

Hair follicle

the three layers that comprise the hair shaft are

Cuticle, Cortex, Medulla

the scales of most animal hairs can be described as having the appearance of shingles on a roof.

True

the_____ contains the pigment granules that impart color to hair

Cortex

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 medullar index of less than_____; the hair of most animals has an index of _____ or greater.

1/3
1/2

Human head hairs generally exhibit (continuous, absent) medullae.

Absent

If a medulla exhibits a patterned shape, the hair is (human, animal) in origin.

Animal

The three stages of hair growth are

Anagen, Catagen, Telogen

A sing hair (can, cannot) be individualized to one person by microscopic examination.

Cannot

In making hair comparisons, it is best to view the hairs side by side under a ______ microscope.

Comparison

_____ hairs are short and curly, with wide variation in shaft diameter.

Pubic

It (is, is not) possible to determine the time when hair was last bleached or dyed

Is

The age and sex of the individual from whom a hair sample has been taken can be determined through an examination of the hair's morphological features.

False

Hair forcibly removed from the body (always, often) has follicular tissue adhering to its root.

Often

Microscopical hair comparisons must be regarded by police and courts as presumptive in nature and all positive microscopical hair comparisons must be confirmed by ______ typing.

DNA

currently, it is possible for DNA typing to provide individualization of a single hair.

False

A ______ hair root is a likely candidate for DNA typing.

Anagen

A minimum collection of ______ full length hairs will normally ensure a representative sampling of head hair.

50

A minimum collection of ______ full length pubic hairs is recommended to cover the range of characteristics present in this region of the body.

24

________ fibers are derived totally from animal or plant sources.

Natural

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 _______

Book answer:Man made
my answer: SYNTHETIC

Polyester was the first synthetic fiber.

False

______ are composed of a large number of atoms arranged in repeating units.

Polymers

The basic unit of the polymer is called the

Monomer

______ are polymers composed of thousands of amino acids linked in a highly organized arrangement and sequence.

Proteins

A first step in the forensic examination of fibers will be the comparison of color and diameter.

True

The microspectrophotmeter employing _______ light is a convenient way for analysts to compare the colors of fibers through spectral patterns.

Visible

The dye components removed from fibers can be separated and compared by _______ chromatography

Pyrolysis Gas Chromatography

Synthetic fibers possess the physical property of ______ because they are crystalline.

Birefringence

The micrspectrophotometer employing ______ light provides a rapid and reliable method fro identifying the generic calls of a single fiber.

Infrared

Normally, fibers possess (individual, class) characteristics.

Class

The two most important components of dried paint from the criminalist's point of view are the _____ and the ______

Individual, Vehicle

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 ________.

Binder

The _______ layer provides corrosion resistance for the automobile.

Electrocoat primer

"Eye appeal" of the automobile comes from the ______ layer.

Base coat

Pyrolysis gas chromatography is a particularly valuable technique for characterizing paint's (binder, pigments).

Binder

Emission spectroscopy can be used to identify the (inorganic, organic) components of paint's pigments.

Inorganic

Paint samples removed for examination must always include all of the paint layers.

True