lab final prep

Question 1

trace evidence: What is an element

Answer 1

A pure substance made of only one type of atom,cannot be decomposed by chemical means.

Question 2

trace evidence: what is the periodic table used for?

Answer 2

Organizes elements by atomic number and groups them by chemical properties and electron structure

Question 3

trace evidence: What are the three main phases of matter?

Answer 3

solid, liquid and gas and plasma

Question 4

trace evidence: what is a phase change?

Answer 4

a physical change between states of matter (melting, freezing, evaporation, sublimation, deposition, condensation)

Question 5

trace evidence: what is density?

Answer 5

, Mass per unit volume; used to compare glass fragments.

Question 6

trace evidence: What is refractive index?

Answer 6

The ratio of the speed of light in a vacuum to the speed of light in a substance.

Question 7

trace evidence: What is the Becke line?

Answer 7

A bright halo that moves toward the material with the higher refractive index.

Question 8

trace evidence:What is the prismatic effect in glass?

Answer 8

The bending of light into colored bands when passing through glass.

Question 9

GLASS FRACTURE ANALYSIS: What is the conical fracture caused by a bullet hole called?

Answer 9

A cone fracture or cone-shaped crater.

Question 10

glass fracture: What are radial fractures?

Answer 10

Long cracks radiating outward from the point of impact. form 1st

Question 11

glass fracture:What are concentric fractures?

Answer 11

Circular cracks formed around the point of impact. form 2nd

Question 12

glass: How can bullet impacts be sequenced?

Answer 12

By using the 3R Rule: Radial fractures form at Right angles to the Rear of impact. Newer fractures stop when they reach older fractures.

Question 13

glass:How do radial fractures help determine direction?

Answer 13

They form on the opposite side of the force.

Question 14

In the glass fracture diagram, what do the long cracks radiating outward from the bullet hole represent?

Answer 14

Radial fractures.

Question 15

In the glass fracture diagram, what do the circular cracks surrounding the point of impact represent?

Answer 15

Concentric fractures.

Question 16

In the glass fracture diagram, how do you determine the sequence of impacts?

Answer 16

New cracks stop when they meet older cracks; earlier fractures continue uninterrupted.

Question 17

According to the bullet-hole diagram, which side of the glass has the wider exit cone?

Answer 17

The side opposite the bullet’s entry point (the bullet exits with a larger, bevelled cone).

Question 18

glass: In the labeled diagram, what does part (a) represent?

Answer 18

The center of impact / bullet hole.

Question 19

glass:In the labeled diagram, what does part (b) represent?

Answer 19

Radial fractures extending from the first impact.

Question 20

glass:In the labeled diagram, what does part (c) represent?

Answer 20

The second bullet impact’s fracture pattern.

Question 21

glass:In the labeled diagram, what does part (d) represent?

Answer 21

A section of radial fractures from an earlier impact.

Question 22

glass:In the labeled diagram, what does part (e) represent?

Answer 22

Concentric (circular) fractures around an impact point.

Question 23

How are paint chips analyzed?

Answer 23

Layer-by-layer comparison using microscopes, FTIR, and color analysis.

Question 24

Why is paint layer structure important?

Answer 24

The number and order of layers can match a specific make/model of vehicle. factory paint is applied in a specific sequence (electrocoat → primer → basecoat → clear coat).
Each manufacturer has unique combinations.

Question 25

What can paint comparison tell an investigator? ,

Answer 25

Possible vehicle manufacturer, repaint history, and if two samples share a common origin.Type of vehicle, model year range, manufacturer, and possible source of the paint transfer.

Question 26

What are the major parts of hair?

Answer 26

Cuticle, Cortex, Medulla (The central canal inside the hair. Its pattern can indicate species and occasionally help with identification.).

Question 27

What part of hair contains most forensic value?

Answer 27

Cortex (contains pigment and microscopic features).

Question 28

Where is nuclear DNA found in hair?

Answer 28

In the follicle/root.

Question 29

Where is mitochondrial DNA found in hair?

Answer 29

In the shaft.especially the cortex.

Question 30

What does mitochondrial DNA tell you?

Answer 30

Maternal lineage.

Question 31

Examples of synthetic fibers

Answer 31

Nylon, Polyester, Acrylic, Rayon

Question 32

How are fibers characterized?

Answer 32

Microscopy, cross-section, burning tests, chemical solubility, refractive index.

Question 33

What properties are examined when comparing fibers?

Answer 33

Color, diameter, cross-sectional shape, dye composition.

Question 34

What are the building blocks of DNA?

Answer 34

Nucleotides (sugar + phosphate + base).

Question 35

What is PCR?

Answer 35

Polymerase Chain Reaction; amplifies small quantities of DNA.

Question 36

What is mitochondrial DNA?

Answer 36

DNA found in the mitochondria; inherited maternally and more stable.

Question 37

Difference between nuclear DNA and mtDNA?

Answer 37

Nuclear = found in nucleus, 46 chromosomes, inherited from both parents, unique to individual; mtDNA = circular, maternal lineage, many copies per cell.

Question 38

What are loci?

Answer 38

Specific chromosomal regions tested in STR analysis

Question 39

What are alleles?

Answer 39

Variations of STR repeat numbers at each locus.

Question 40

How to identify DNA contributors in the underwear stain?

Answer 40

Compare each locus’ alleles to the victim and suspects; matches across multiple loci indicate the contributor. Stain shows alleles matching victim + one suspect. Underwear stain alleles: D8S1179: 13,15 → matches suspect #2 (13,15) D21S11: 30 → matches suspect #2 (30) Other loci match suspect #2 AND victim → Conclusion: mixture of victim + suspect #2.

Question 41

Based on the DNA chart, who contributed to the underwear stain?

Answer 41

The stain matches suspect #2 (exact allele match across all loci) and victim.

Question 42

In the DNA table, what does each column header (D8S1179, D21S11, etc.) represent?

Answer 42

Each header is a locus—an STR area on a chromosome.

Question 43

dna: What does AMEL identify?

Answer 43

, Biological sex: X = female, X/Y = male.

Question 44

dna: How do you know suspect #1 is not a contributor

Answer 44

Several loci do not match the stain (TH01, D19S433, etc.).

Question 45

dna: How do you recognize a mixture?

Answer 45

More than two alleles appear at a locus.

Question 46

What is blood composed of?

Answer 46

Plasma, red blood cells, white blood cells, and platelets.

Question 47

blood and serology: What tests identify blood?

Answer 47

Presumptive tests (Kastle-Meyer, luminol), and confirmatory tests (Teichmann, Takayama, RSID).

Question 48

blood and serology: What are buccal cells?

Answer 48

Cheek cells used as a DNA reference sample

Question 49

blood and serology: How should biological evidence be stored?

Answer 49

In paper containers to prevent mold and allow drying.

Question 50

blood and serology: What are impact spatters?

Answer 50

Blood dispersed from forceful impact.

Question 51

blood and serology: What are transfer stains?

Answer 51

Patterns made when a bloody object contacts a surface.

Question 52

blood and serology: What are flow patterns?

Answer 52

Blood movement due to gravity

Question 53

blood and serology: How is the angle of impact calculated?

Answer 53

sin(θ) = width ÷ length.

Question 54

LAW & FORENSICS: What are the elements of a crime? ,

Answer 54

Actus reus (guilty act, intent) + Mens rea (guilty mind, the act).

Question 55

What are the Federal Rules of Evidence?

Answer 55

Rules governing what evidence may be admitted in court.

Question 56

Which rule governs expert testimony?

Answer 56

FRE Rule 702 defines qualifications and reliability standards for experts.

Question 57

What is an expert witness?

Answer 57

A qualified specialist who can give opinion-based testimony.

Question 58

What is a lay witness?

Answer 58

A non-expert who testifies only to what they observed.

Question 59

What is cross-examination?

Answer 59

Questioning by the opposing attorney; guaranteed by the 6th Amendment.

Question 60

What was the Frye case?

Answer 60

Established the “general acceptance” standard for scientific evidence. It set early rules for admitting scientific procedures.

Question 61

What was the Daubert case? and its significance

Answer 61

Established new criteria for scientific evidence reliability (testability, peer review, error rate, standards, acceptance).It shifted judges into “gatekeepers” of scientific evidence.

Question 62

What is Rosario material?

Answer 62

Prior statements by a prosecution witness that must be disclosed to the defense. It protects defendants’ right to cross-examine and challenge witness statements.