Lec 5: STR limitations and SNPs
### Questions on the Limitations of Forensic DNA Testing
#### Technique and Amplification Errors
1. Does the technique used in forensic DNA testing make mistakes in amplifying bands?
- A) Frequently
- B) Probably not; early discussions focused on RFLP, now PCR
- C) Occasionally, especially with advanced techniques
- D) Never
- Correct Answer: B
#### Risks of Sample Contamination
2. What are the risks of sample contamination in forensic DNA testing?
- A) Insignificant
- B) Moderate
- C) Very significant
- D) Non-existent
- Correct Answer: C
3. At which stages can sample contamination occur?
- A) During sample collection
- B) During storage
- C) During analysis
- D) All of the above
- Correct Answer: D
#### Objectivity of Band Recognition
4. How objective is band recognition in forensic DNA testing?
- A) Completely objective
- B) Completely subjective
- C) A recent study suggests this can be subjective, at least in part
- D) Uncertain, varies with technique
- Correct Answer: C
5. What can influence the interpretation of band patterns from capillary trace?
- A) The quality of the equipment used
- B) The experience of the investigator
- C) The investigator's knowledge of the sample
- D) The environment in which the test is conducted
- Correct Answer: C
#### Likelihood and Robustness of ‘Random’ Matches
6. What is the likelihood of a ‘random’ match in forensic DNA testing?
- A) Very low, statistically insignificant
- B) Moderate, varies with population
- C) Still very contentious
- D) High, especially with degraded samples
- Correct Answer: C
7. How robust are the statistics on matching samples to suspects?
- A) Very robust, universally agreed upon
- B) Somewhat robust, but contentious
- C) Weak, generally unreliable
- D) Dependent on the specific laboratory
- Correct Answer: B
8. What factors contribute to the uncertainty in methods of assessing DNA matches?
- A) Different groups have different frequencies of some alleles
- B) Variation in laboratory techniques
- C) The subjective nature of interpreting results
- D) All of the above
- Correct Answer: D
#### Overall Limitations of DNA Typing
9. Is DNA typing infallible compared to other forensic analyses?
- A) Yes, it is the most reliable forensic method
- B) No, DNA typing is no more infallible than any other forensic analysis
- C) It depends on the case
- D) Only in specific scenarios
- Correct Answer: B
10. Which of the following is NOT a technical limitation of current STR technology?
- A) Capillary sequencers are old technology
- B) STR relies on DNA of length ≈ 500 bp
- C) STR is directly sequence-based
- D) Difficult to amplify degraded DNA
- Correct Answer: C
#### Summary and General Knowledge
11. Which statement summarizes the limitations discussed in the lecture?
- A) Forensic DNA testing is perfect and without flaws
- B) Forensic DNA testing has some limitations but is generally reliable
- C) Forensic DNA testing is outdated and should be replaced immediately
- D) Forensic DNA testing is as subjective and fallible as other forensic analyses
- Correct Answer: D
These questions cover the various aspects of limitations in forensic DNA testing, including technical issues, risks of contamination, subjectivity in interpretation, and the robustness of statistical matching.