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WorksheetsCh. 4 Review - Fibers
Total questions: 35
Worksheet time: 47mins
Natural fibers can be obtained from
Plants and animals
Only from plants
Only from animals
Plants, animals, and minerals
Fibers are considered to be
Class evidence
Individual evidence
Trace evidence
Physical evidence
Direct evidence
What characteristics of cotton make it great to use for clothing
It is very easy to grow
It is resistant to staining
The fibers are easily woven and dyed
The fibers are extremely long
Mineral fibers such as asbestos are very durable. These fibers are used in all of the following except
Rope
Shingles
Floor tiles
Insulation
All of the following are characteristics of a synthetic fiber except
They are man-made
They are used in the production of carpet fibers
They are made of a long string of repeating chemical units called monomers
They do not contain natural polymers
A characteristic of natural fibers is that they
Are stronger than synthetic fibers
Will break down when exposed to bright light
Melt at a lower temperature than synthetic fibers
Are affected by microscopic organisms
Which of the following observations are used to help identify a specific fiber?
Smell of the burned fiber
On contact with flame, does the fiber coil or melt?
Color and structure of the residue left after the fiber burns
All of the above
Fibers are an excellent source of trace evidence because
They are easily transferred from victim to suspect
They are often overlooked by a suspect
They can be easily collected and stored
All of the above
A fiber is collected at the crime scene. When viewed under a compound microscope, what two traits would indicate that the fiber was a human hair and not a piece of fiber obtained from an article of clothing? (Choose 2)
The presence of a cuticle
A medullary index of 0.33 or less
A wide diameter
Its ability to dissolve in water
Match the fibers to the correct source
cotton
linen
hemp
manila
wool
silk
asbestos
fiberglass
cashmere
Match the characteristics to the two different types of fibers.
damaged by micro-organisms
can have a cuticle
stronger
deteriorate in bright sun
melt at lower temperatures
very regular diameters
variation between fibers under the microscope
Classify each fiber analysis procedure as Destructive or Nondestructive.
burn test
polarizing light microscopy
infrared spectroscopy
solubility in solvents
absorption of stains
density
chromatography of dye
Explain why the presence of a white cotton fiber found on a suspect and found on a victim at a crime scene is not enough evidence to convict the suspect.
Which of the following are appropriate methods to collect fibers? Select all that apply
forceps
tape
vacuum
fingers (no gloves)
Reorder the following
Fiber
Yarn
Textile
Multiple garments collected from the victim can be placed in the same evidence bag.
True
False
A large sheet or curtains must be laid on a clean sheet of paper and rolled up so the evidence stays intact.
True
False
When fibers are transferred from victim to suspect or suspect to victim, this is called:
direct transfer
secondary transfer
If hairs from a dog are found in Mrs. Miller's classroom, it is most likely due to
direct transfer
secondary transfer
Which of the following observations are used to help identify a specific fiber?
smell of the burned fiber
on contact with the flame, does the fiber coil or melt?
color and structure of the residue left after the fiber burn
all of the above
Early collection of fibers in an investigation is critical. Within 24 hours, an estimated __% of fibers may have been lost from a crime scene.
85%
50%
95%
25%
A folded paper used to hold trace evidence
envelope
baggie
bindle
chain of custody
Match the following
wool
cotton
polyester
When using fiber as evidence, forensic scientists want to determine which of the following? Select all that apply.
type of fiber
fiber color
number of fibers
where fiber was found
source of fiber
Knowing the type of crime committed helps forensic scientists collect evidence. Explain why with the example of breaking and entering.
Scientists use this test to see the chemical structure of a fiber using beams of light:
Neutron Activation Analysis
Polarizing Light Microscopy
Long strings of repeating chemical units that make up synthetic fibers are called:
Strands
Fibers
Yarns
Polymers
