Q: A DNA profile from a crime scene matches a suspect at 13 STR loci. What is the probability that this match occurred by chance, assuming each locus is independent and the genotype frequencies are $$p_1$$, $$p_2$$, ..., p_{13}$$?

The probability is $$p_1$$ \times $$p_2$$ \times ... \times p_{13}$$.

Question 1

Which DNA technique is most suitable for analyzing highly degraded samples from ancient remains?

Accepted Answer

Mitochondrial DNA profiling

Question 2

A forensic scientist needs to compare DNA from a small blood stain found at a crime scene. Which method is most appropriate for amplifying the DNA for analysis?

Accepted Answer

Polymerase chain reaction (PCR)

Question 3

Which of the following statements about STRs (Short Tandem Repeats) is correct?

Accepted Answer

STRs are 2–6 base pairs in length and are also called microsatellites.

Question 4

In a rape case with multiple male suspects, which DNA profiling method is most useful for distinguishing male DNA from female DNA?

Accepted Answer

Y chromosome STR profiling

Question 5

Which of the following is a limitation of VNTR analysis compared to STR analysis?

Accepted Answer

VNTR analysis requires a large amount of DNA and is less effective with degraded samples.

Question 6

A DNA profile from a crime scene matches a suspect at 13 STR loci. What is the probability that this match occurred by chance, assuming each locus is independent and the genotype frequencies are $$p_1$$, $$p_2$$, ..., p_{13}$$?

Accepted Answer

The probability is $$p_1$$ 	imes $$p_2$$ 	imes ... 	imes p_{13}$$.

Question 7

Which ethical issue is most directly related to the use of commercial DNA databases like 23andMe and Ancestry in forensic investigations?

Accepted Answer

The legality of collecting DNA without consent

Question 8

Which step is NOT part of the standard VNTR analysis workflow?

Accepted Answer

PCR amplification

Question 9

A forensic lab is comparing DNA profiles from two individuals using STR loci. Which scenario would indicate a non-match?

Accepted Answer

One individual has alleles at a locus that are not present in the other individual's profile.

Question 10

Which of the following best describes a single nucleotide polymorphism (SNP)?

Accepted Answer

A single base difference between individuals at a specific locus

Question 11

Why is mitochondrial DNA profiling particularly useful for identifying remains in missing persons cases?

Accepted Answer

It is inherited maternally and exists in many copies per cell, making it easier to recover from degraded samples.

Question 12

Which of the following is a technical limitation of DNA forensics?

Accepted Answer

Human error in sample handling

Question 13

In the context of DNA forensics, what is the primary purpose of the Combined DNA Index System (CODIS)?

Accepted Answer

To store and compare STR profiles from convicted offenders and crime scenes

Question 14

A paternity test uses STR loci to compare a child's DNA to two potential fathers. If the child shares alleles with only one of the men at all tested loci, what is the most likely conclusion?

Accepted Answer

The man who shares alleles at all loci is most likely the biological father.

Question 15

Which DNA technique is most likely to be used for species identification in food samples?

Accepted Answer

Mitochondrial DNA analysis

Question 16

DNA phenotyping can be used to predict which of the following traits from a DNA sample?

Accepted Answer

Eye, hair, and skin color

Question 17

Which scenario best illustrates the importance of using multiple loci in DNA profiling?

Accepted Answer

Multiple STR loci are used, reducing the probability of a random match.

Question 18

Which of the following is NOT an ethical concern in DNA forensics?

Accepted Answer

Amplifying DNA using PCR

Question 19

A forensic scientist is interpreting a DNA profile and finds a partial match between a crime scene sample and a database entry. Which issue must be considered before pursuing this lead?

Accepted Answer

The legality and ethics of pursuing partial matches

Question 20

Which of the following best explains why identical twins cannot be distinguished using standard autosomal STR profiling?

Accepted Answer

They have identical autosomal STR profiles due to their shared genetic material.

DNA Forensics: Techniques, Interpretation, and Ethical Issues

Study Guide - Practice Questions

Study Guide - Flashcards