FRSC 2030 Final Questions And
Answers 2025
National DNA Data Bank total offender hits since 2000 - Answer - 65,568
True or False, DNA collected from a biological sample at a crime scene can provide absolute proof of guilt
if it matches a suspect? - Answer - false, DNA can exclude an individual but can't prove it came from an
individual, if dna profile matches you must consider the chances that there is an identical dna profile in
the population
Forensic scientist should - Answer - put physical evidence into context, not prove innocence or guilt
more context acquired for evidence - Answer - the better
Purpose of Presumptive Test - Answer - help provide initial context at crime scenes as to where biological
stains are (despite having been cleaned, diluted, or if they are clear/colourless and hard to see), what
type biological stain is present (e.g., blood, semen, saliva), and the patterns of the biological stains (e.g.,
for blood spatter analyses
3 categories of presumptive tests - Answer - colour tests, luminescence tests, and antibody precipitin
tests
Kastle-Meyer Test - Answer - phenolphthalein reacts with the blood's hemoglobin in the presence of
hydrogen peroxide and is oxidized from its colorless form to a bright/deep pink color, not human blood
specific
Hemastix - Answer - fast and easy, a strip that has been coated with tetramethylbenzidine (TMB) and will
produce a green color with the presence of hemoglobin, not specific to human blood
,Luminol and bluestar - Answer - react with oxidizing agents, such as the heme in blood, to emit light, or
luminescence
Advantage of luminol/bluestar - Answer - finding minute traces of blood, including after a crime scene
has been cleaned and can tell if body was moved
Drawback of luminol/bluestar - Answer - reaction is not specific to blood, and other oxidizing agents like
bleach, some metals, and plant material can also cause luminescence with luminol
Precipitin Tests - Answer - serological tests to detect the presence of a specific antigen, such as human
specific blood antigens
Hematrace - Answer - uses the principles of the precipitin test to detect human heme in hemoglobin
antigens
How hematrace works - Answer - The test works when human hemoglobin antigens react with the
monoclonal antihuman antibodies that are labelled with a pink dye. When/if the antigens and antibodies
complex, a pink line is formed
Tests for Semen - Answer - needed because large percentage of cases are sexual assault, microscopic
examination of spermatozoa is performed along with presumptive and confirmation tests
Presumptive and confirmation semen test - Answer - presumptive- acid phosphatase test (colour)
confirmation- prostate specific antigen test (human)
Acid phosphatase test - Answer - high levels in human semen, has chemical activity that changes colour
when it detects monophenolic phosphoric acid, can take a a while to react
p30 test - Answer - Human semen also contains high levels of a substance called p30 or prostate specific
antigen, a protein which, with few exceptions, is specific to semen. The technique is very sensitive in
detecting minute amounts of this protein
,Presumptive tests for saliva - Answer - saliva contains alpha-amylase, this enzyme can be detected using
the Phadebas test, it turns blue
Other bodily fluids that have acid phosphatase - Answer - semen and vaginal secretions
Why are antibody tests important in identifying bodily fluids beyond just colour tests? - Answer - they
are often more specific, and less likely to give false positives based on cross-reactivity with other
substances
DNA - Answer - deoxyribonucleic acid is a set of four molecules that all include a sugar backbone, a
phosphate group and one of 4 different nucleotide bases (A, G, C, T)
Nuclear DNA - Answer - DNA within the nucleus is divided into chromosomes, 22 pairs of matched
chromosomes and 2 sex chromosomes (X and Y chromosomes).
Chromosomes in somatic cell - Answer - 46, are diploid- all chromosomes are paired
Somatic cells - Answer - can identify an individual from dna bc each cell has 2 copies of entire genome 2n
Gametes (sperm or egg) - Answer - haploid (one copy of each of the 23 chromosomes), 1n
A single sperm would have - Answer - 1n copies of genome
Coding part of DNA - Answer - (DNA that encodes for proteins) consists of ~30, 000 genes, or ~ 5% of
human genome
A specific region of DNA is called a locus (pl.: loci) - Answer - each adding power to our ability to
segregate between individual DNA profiles, with the cumulation of the power of these loci to distinguish
between individuals being extremely high
Example of the power of loci - Answer - chance that two unrelated individuals have the same DNA profile
by chance could be as high as 1 in several trillion - or not very likely!
, Mendelian Inheritance - Answer - getting half your DNA from each of your parents
Mitochondrial DNA (mtDNA) - Answer - small, several hundred copies in a given cell, maternally
inherited
Advantages of mtDNA - Answer - so many more copies per cell than nDNA, therefore small, degraded
evidence will more likely provide a mtDNA profile
Disadvantages to mtDNA - Answer - not all individuals have different copies of mtDNA, ability to
distinguish between individuals is much lower for mtDNA bc you can only trace maternal lineage
Paternal Inheritance (Y-chromosomes) - Answer - Y chromosome is not inherited from both parents, but
only from your father
Is the mtDNA or nDNA genome bigger? - Answer - mtDNA 17, 000 bp, nDNA 3.2 billion bp
What is the ploidy of human nDNA? - Answer - Diploid, copy from mom and a copy from dad
Where is mtDNA found - Answer - cytoplasm
What is an allele? - Answer - A genetic variant of a locus
Similarity of humans - Answer - 1/1000 bp differ between unrelated individuals, meaning that most
humans are 99.9% similar to each other
Bp difference amongst individuals - Answer - 6 million bp different between unrelated individuals that
can be used to unique identify a person
CODIS 13 loci - Answer - fraction of genomic variation looked at to distinguish dna profiles
Answers 2025
National DNA Data Bank total offender hits since 2000 - Answer - 65,568
True or False, DNA collected from a biological sample at a crime scene can provide absolute proof of guilt
if it matches a suspect? - Answer - false, DNA can exclude an individual but can't prove it came from an
individual, if dna profile matches you must consider the chances that there is an identical dna profile in
the population
Forensic scientist should - Answer - put physical evidence into context, not prove innocence or guilt
more context acquired for evidence - Answer - the better
Purpose of Presumptive Test - Answer - help provide initial context at crime scenes as to where biological
stains are (despite having been cleaned, diluted, or if they are clear/colourless and hard to see), what
type biological stain is present (e.g., blood, semen, saliva), and the patterns of the biological stains (e.g.,
for blood spatter analyses
3 categories of presumptive tests - Answer - colour tests, luminescence tests, and antibody precipitin
tests
Kastle-Meyer Test - Answer - phenolphthalein reacts with the blood's hemoglobin in the presence of
hydrogen peroxide and is oxidized from its colorless form to a bright/deep pink color, not human blood
specific
Hemastix - Answer - fast and easy, a strip that has been coated with tetramethylbenzidine (TMB) and will
produce a green color with the presence of hemoglobin, not specific to human blood
,Luminol and bluestar - Answer - react with oxidizing agents, such as the heme in blood, to emit light, or
luminescence
Advantage of luminol/bluestar - Answer - finding minute traces of blood, including after a crime scene
has been cleaned and can tell if body was moved
Drawback of luminol/bluestar - Answer - reaction is not specific to blood, and other oxidizing agents like
bleach, some metals, and plant material can also cause luminescence with luminol
Precipitin Tests - Answer - serological tests to detect the presence of a specific antigen, such as human
specific blood antigens
Hematrace - Answer - uses the principles of the precipitin test to detect human heme in hemoglobin
antigens
How hematrace works - Answer - The test works when human hemoglobin antigens react with the
monoclonal antihuman antibodies that are labelled with a pink dye. When/if the antigens and antibodies
complex, a pink line is formed
Tests for Semen - Answer - needed because large percentage of cases are sexual assault, microscopic
examination of spermatozoa is performed along with presumptive and confirmation tests
Presumptive and confirmation semen test - Answer - presumptive- acid phosphatase test (colour)
confirmation- prostate specific antigen test (human)
Acid phosphatase test - Answer - high levels in human semen, has chemical activity that changes colour
when it detects monophenolic phosphoric acid, can take a a while to react
p30 test - Answer - Human semen also contains high levels of a substance called p30 or prostate specific
antigen, a protein which, with few exceptions, is specific to semen. The technique is very sensitive in
detecting minute amounts of this protein
,Presumptive tests for saliva - Answer - saliva contains alpha-amylase, this enzyme can be detected using
the Phadebas test, it turns blue
Other bodily fluids that have acid phosphatase - Answer - semen and vaginal secretions
Why are antibody tests important in identifying bodily fluids beyond just colour tests? - Answer - they
are often more specific, and less likely to give false positives based on cross-reactivity with other
substances
DNA - Answer - deoxyribonucleic acid is a set of four molecules that all include a sugar backbone, a
phosphate group and one of 4 different nucleotide bases (A, G, C, T)
Nuclear DNA - Answer - DNA within the nucleus is divided into chromosomes, 22 pairs of matched
chromosomes and 2 sex chromosomes (X and Y chromosomes).
Chromosomes in somatic cell - Answer - 46, are diploid- all chromosomes are paired
Somatic cells - Answer - can identify an individual from dna bc each cell has 2 copies of entire genome 2n
Gametes (sperm or egg) - Answer - haploid (one copy of each of the 23 chromosomes), 1n
A single sperm would have - Answer - 1n copies of genome
Coding part of DNA - Answer - (DNA that encodes for proteins) consists of ~30, 000 genes, or ~ 5% of
human genome
A specific region of DNA is called a locus (pl.: loci) - Answer - each adding power to our ability to
segregate between individual DNA profiles, with the cumulation of the power of these loci to distinguish
between individuals being extremely high
Example of the power of loci - Answer - chance that two unrelated individuals have the same DNA profile
by chance could be as high as 1 in several trillion - or not very likely!
, Mendelian Inheritance - Answer - getting half your DNA from each of your parents
Mitochondrial DNA (mtDNA) - Answer - small, several hundred copies in a given cell, maternally
inherited
Advantages of mtDNA - Answer - so many more copies per cell than nDNA, therefore small, degraded
evidence will more likely provide a mtDNA profile
Disadvantages to mtDNA - Answer - not all individuals have different copies of mtDNA, ability to
distinguish between individuals is much lower for mtDNA bc you can only trace maternal lineage
Paternal Inheritance (Y-chromosomes) - Answer - Y chromosome is not inherited from both parents, but
only from your father
Is the mtDNA or nDNA genome bigger? - Answer - mtDNA 17, 000 bp, nDNA 3.2 billion bp
What is the ploidy of human nDNA? - Answer - Diploid, copy from mom and a copy from dad
Where is mtDNA found - Answer - cytoplasm
What is an allele? - Answer - A genetic variant of a locus
Similarity of humans - Answer - 1/1000 bp differ between unrelated individuals, meaning that most
humans are 99.9% similar to each other
Bp difference amongst individuals - Answer - 6 million bp different between unrelated individuals that
can be used to unique identify a person
CODIS 13 loci - Answer - fraction of genomic variation looked at to distinguish dna profiles
