BSFS Forensic Biology and DNA Analysis

Question 1

Which technique is considered the gold standard for forensic DNA profiling in the United States today?

Accepted Answer

Short tandem repeat (STR) analysis

Answer

STR analysis is the FBI's current standard because it is highly discriminating, requires only a small amount of DNA, and is fully automated for CODIS database searching.

Question 2

CODIS, the national DNA database used by forensic labs in the U.S., stands for:

Accepted Answer

Combined DNA Index System

Answer

CODIS is the FBI's national database that links DNA profiles from crime scenes with known offenders to assist in solving crimes across jurisdictions.

Question 3

The presumptive test for semen that detects the enzyme acid phosphatase is known as:

Accepted Answer

AP spot test (acid phosphatase test)

Answer

The acid phosphatase spot test detects high concentrations of AP secreted by the prostate gland in semen, producing a purple color as a presumptive result.

Question 4

Polymerase chain reaction (PCR) is used in forensic DNA analysis primarily because it:

Accepted Answer

Amplifies small or degraded DNA samples into quantities sufficient for analysis

Answer

PCR exponentially replicates target DNA sequences, enabling analysis of trace or degraded biological evidence that would otherwise be insufficient for profiling.

Question 5

Mitochondrial DNA (mtDNA) analysis is preferred over nuclear STR typing when:

Accepted Answer

Evidence such as hair shafts without roots or aged bones contains insufficient nuclear DNA

Answer

mtDNA is present in thousands of copies per cell compared to two copies of nuclear DNA, making it recoverable from degraded evidence with minimal nuclear DNA.

BSFS - Bachelor of Science in Forensic Science Practice Test

BSFS - Bachelor of Science in Forensic Science Practice Test

BSFS Forensic Biology and DNA Analysis