Week 1-4 Forensic Science: Foundations, Serology, DNA, Toxicology, and TOD - Practice Flashcards

A set of practice flashcards in QUESTION_AND_ANSWER format, covering foundations of forensic science, serology, DNA analysis, forensic toxicology, and time-of-death concepts as presented in the notes.

What is the role of a Forensic Pathologist?

Perform autopsies and determine the cause of death.

What is the role of a Forensic Biologist?

Analyze bodily fluids and DNA.

What is the role of a Forensic Chemist?

Test unknown substances (e.g., drugs, explosives).

What is the role of a Forensic Toxicologist?

Analyze toxins, drugs in biological samples.

What do Crime Scene Examiners (CSEs) do?

Collect and document physical evidence.

What is the role of an Odontologist in forensics?

Identify individuals via dental records.

What does an Anthropologist do in forensic investigations?

Identify skeletal remains and assess trauma.

What do Digital Forensics Experts do?

Extract and analyse electronic data.

Why is collaboration important in forensic cases?

Cases often require input from multiple disciplines.

What is a positive control?

A positive control confirms that the test is working (e.g., known blood sample).

What is a negative control?

A negative control ensures specificity (e.g., clean swab).

What is the purpose of replicates in testing?

Testing the same sample multiple times for reliability.

What is blinding in forensic testing?

Preventing biased results by concealing sample identity.

What is randomisation and why is it used in testing?

Randomisation reduces bias by randomly assigning samples/tests.

What are confounding variables?

External factors that can affect results (e.g., environmental factors).

What are Standard Operating Procedures (SOPs)?

Documented procedures to ensure consistency and repeatability.

Why should you avoid assumptions in analysis?

To prevent bias and ensure objective interpretation.

What does statistical significance mean?

The likelihood that a result is not due to chance.

What is a Type I error?

False positive—rejecting a true null hypothesis.

What is a Type II error?

False negative—failing to reject a false null hypothesis.

What is deductive reasoning in forensic science?

General principle applied to a specific case (e.g., Newton's laws).

What is inductive reasoning?

Specific observations leading to a general conclusion.

What is abductive reasoning?

Best explanation based on incomplete evidence.

What biological fluids can serology identify at crime scenes?

Blood, semen, saliva, and urine.

Why is serology important before DNA testing?

Provides context and guides subsequent DNA analysis.

What kind of context can serology indicate?

Indicates presence of violence or sexual activity.

What is a presumptive test?

Fast, inexpensive test that suggests a substance is present but is not definitive.

Give an example of a presumptive test for blood.

Kastle-Meyer test—pink indicates positive for blood.

What is a confirmatory test?

Laboratory-based test providing a more definitive identification.

Give an example of a confirmatory test for blood.

Takayama test (blood) or similar confirmatory methods.

What does Kastle-Meyer indicate in serology?

A presumptive test for blood.

What does Hematrace indicate?

A confirmatory test for blood.

What is a presumptive test for semen?

Acid phosphatase test.

What are confirmatory tests for semen?

PSA testing and microscopy.

What test is used to detect saliva?

Phadebas test.

What factors determine the choice of serological tests?

Sample type and context.

What factors should be evaluated when interpreting serological results?

Staining pattern, location, and volume.

Why must degradation be considered in serology?

Degradation can affect results and interpretation.

Why must contamination be considered in serology?

Contamination can lead to false conclusions.

How do serological findings relate to case narratives?

They link staining to events like assault or struggle.

What is STR in DNA analysis?

Short Tandem Repeat — highly polymorphic DNA marker used for profiling.

What are the basic steps in DNA analysis?

Sample collection, DNA extraction, quantification, PCR amplification, separation/detection by electrophoresis.

Why is contamination control essential in DNA work?

To prevent false matches and erroneous results.

What are common applications of DNA fingerprinting?

Suspect identification, cold case resolution, missing persons, disaster victim identification.

What are typical applications of DNA databases?

Matching DNA profiles and performing familial searches (e.g., NCIDD).

What does STR stand for and how is it used in forensics?

Short Tandem Repeat; used to compare loci between DNA samples.

What does VNTR stand for?

Variable Number Tandem Repeat—older method with larger repeats.

What does RFLP stand for and why is it considered outdated?

Restriction Fragment Length Polymorphism; an older method requiring larger DNA quantities.

What does PCR stand for?

Polymerase Chain Reaction; amplifies small DNA samples.

What is SNP in forensics?

Single Nucleotide Polymorphism; used in phenotype prediction and additional analyses.

What is mtDNA and when is it useful?

Mitochondrial DNA; useful for degraded samples or maternal lineage.

What is a DNA match probability?

Product of individual allele frequencies across tested loci.

What does a low DNA match probability imply?

Strong evidence supporting a match.

What is the prosecutor's fallacy?

Mistakenly equating match probability with guilt probability.

What are common DNA collection challenges?

Contamination, degradation, and limited sample quantity.

What privacy concerns exist with DNA databases?

Privacy issues and potential misuse.

What does overrepresentation in DNA databanks mean?

Minority groups may be overrepresented in databases.

What are possible misuses or misinterpretations of DNA in court?

Overreliance on statistics or improper interpretation.

What is the role of a forensic toxicologist?

Detect and interpret drugs, poisons, and alcohol in biological samples.

Why is toxicology interpretation context-dependent?

Factors like metabolism, half-life, co-administration and postmortem changes affect results.