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1. Which one of these is not true for stutter bands in DNA analysis?

  1. It refers to the consistent observation of a minor band, one repeat unit smaller
  2. These are observed as “Shadow bands”.
  3. The occurrence of these is much reduced for shorter repeat units.
  4. They are mostly seen/observed in the amelogenin locus.

Answer: (4) They are mostly seen/observed in the amelogenin locus.

Explanation: Stutter peaks are found in almost every electropherogram in the form of small peaks that occur immediately before or after a real peak.

2. If the two genes comprising an allelomorphic pair are identical, the individual is said to be

  1. Heterozygous 
  2. Homozygous
  3. Mutant 
  4. Stutter alleles

Answer: (2) Homozygous

-> Homozygous: two identical alleles at a locus
-> Heterozygous: two different alleles at a locus
-> Hemizygous: if one allele is missing

3. SYBR Green Dye is used for:

  1. HPLC
  2. Immunofluorescence
  3. PCR
  4. ELISA

Answer: (3) PCR

-> SYBR Green is a type of asymmetrical cyanine dye that is used as a nucleic acid stain in molecular biology and fluorescence at 520 nm.
-> Process: As new DNA strands are synthesized during extension, SYBR dye embeds within the double stands. During denaturation (or annealing) when most of the DNA in the tube is still single-stranded, SYBR Green dye releases and doesn’t fluoresce.
-> These interaction dyes are used to assess how much PCR product is being made in each cycle of the reaction since the dyes only fluoresce when bonded to double-stranded DNA.

4. Assertion (A): DNA typing of feces has not proven very successful.

Reason (R): Because a large number of bacteria and digestive enzymes degrade DNA.

  1. Both (A) and (R) are correct
  2. (A) is correct and (R) is incorrect
  3. Both (A) and (R) are incorrect
  4. (A) is incorrect and (R) is correct

Answer: (1) Both (A) and (R) are correct

5. STR DNA analysis can help in determining which of the following?

  1. Age of an individual
  2. Race of an individual
  3. Gender of an individual
  4. Height of an individual

Answer: (3) Gender of an individual

-> STR DNA analysis can be used for gender determination based on the X and Y chromosomal STR loci.
-> Till now, age and height can’t be determined by the STR DNA analysis.
-> While talking about race determination from STR DNA, there is a complex relation and variation of ancestry, genetic makeup, and phenotype. Moreover, there is no specific gene that can be used for race determination.

6. Assertion (A): In cases of mass disasters involving very high-temperature incidents, teeth are considered the most suitable material for DNA analysis.

Reason (R): Cellular material present in the pulp cavity may remain unaffected by extreme conditions.

  1. Both (A) and (R) are incorrect
  2. Both (A) and (R) are correct
  3. (A) is correct but not (R)
  4. (R) is correct but not (A)

Answer: (2) Both (A) and (R) are correct

Explanation: This is the reason why forensic odontology comes in handy in the identification of mass destruction cases.

7. The polymorphic enzymes found in human blood may help in:

  1. Individualization
  2. Polymorphism
  3. Agglutination
  4. Precipitation

Answer: (1) Individualization

Explanation: The polymorphic enzyme (DNA) pattern can be used to identify the individuality of the person. Moreover, it is also proven that the patterns of DNA polymorphisms can also be extracted from two to three-year-old dried bloodstains. So, it means that the results can be used for identification purposes.
Reference: Application of DNA Polymorphisms to the Forensic Examination of Dried Blood Stains

8. Two arms composed mainly of DNA and held together by centromere is:

  1. Gene
  2. Cell
  3. Protein
  4. Chromosome

Answer: (4) Chromosome

Explanation: Two chromatids (newly copied chromosomes) are held together at a region of DNA called the centromere which is responsible for guiding the movement of chromosomes during mitosis and meiosis.
-> Mitosis: Mitosis produces two diploid somatic cells that are genetically identical to each other and the original parent cell.
-> Meiosis: Meiosis produces four haploid gametes that are genetically unique from each other and the original parent cell.
Reference: DNA Structure

9. STRs are highly polymorphic. STR alleles per locus are

  1. 5-20
  2. 50-150
  3. 500-1000
  4. 1000-10000

Answer: (1) 5-20

10. Which of the following is correct about the DNA fingerprint pattern of a child?

  1. It is exactly similar to the DNA fingerprint pattern of both the parents.
  2. 50% bands of DNA fingerprint pattern of the child will be similar to mother and rest similar to father.
  3. 100% similar to the father’s DNA fingerprint pattern.
  4. 100% similar to the mother’s DNA fingerprint pattern.

Answer: (2) 50% bands of DNA fingerprint pattern of the child will be similar to mother and rest similar to father.

11. The restriction enzymes were discovered by which of the following scientists?

  1. Watson and Crick
  2. Boyer and Cohen
  3. Nathan, Arber, and Smith
  4. Jacob and Monad

Answer: (3) Nathan, Arber, and Smith

12. Match the following:

List-I (Type of Satellite DNA)List-II (Size of repeat unit in base pairs)
(a) Microsatellite(i) 6
(b) Minisatellite (telomeric)(ii) 1million – 10 million
(c) Minisatellite (hypervariable)(iii) 100- Several thousand
(d) Satellite(iv) 7-100
 (v) 1-6

Answer: (3) (v), (i), (iv), (iii)

-> Satellites: Tandemly repeated sequences ranging from 2 to 100s of base pairs (bp) per repeat.
-> Microsatellites: Small sequences of 1 to 6 base pairs repeated 10 to 100 times per cluster.
-> Telomeric Minisatellites: Repeat sequence of 1 to 6 (usually 6 i.e. “TTAGGG”’ in humans)
-> Hypervariable Minisatellite: 6 to > 50 bp
-> Short Tandem Repeats (STRs): 3 to 5 bp

13. Which human DNA quantitation standard was released by NIST for use in forensic laboratories?

  1. SRM 2372
  2. SRM 2513
  3. SRM 2317
  4. SRM 2732

Answer: (1) SRM 2372

Explanation: These SRMs are useful for developing the right DNA profile. For developing a DNA fingerprint, the analyst must know how much DNA is required to make a DNA profile. 

14. SRM 2372 was first introduced in:

  1. 1997
  2. 2001
  3. 2007
  4. 2010

Answer: (3) 2007

Explanation: In October 2007, NIST Standard Reference Material (SRM) introduced 2372 as a standard for human DNA quantification. 

15. How many standard samples are provided by NIST in SRM 2372?

  1. Two
  2. Three
  3. Four
  4. Seven

Answer: (2) Three

Explanation: It contains 3 vials of human DNA which are suspended in a clear solution.

16. Vial 2 of SRM 2372 has a standard and precisely measured quantity of_____________.

  1. Male DNA
  2. Female DNA
  3. Transgender DNA
  4. Both (1) and (2)

Answer: (2) Female DNA

Explanation: These different vials (1st for male DNA, 2nd for female, 3rd for mixed human DNA) come in standard and precisely measured quantities of human DNA which are used for the calibration of their instruments.
Reference: Production and certification of NIST Standard Reference Material 2372 Human DNA Quantitation Standard [PubMd.Gov]

17. That there are 23 pairs of chromosomes in man was established by

  1. Tjio & Levan
  2. Landsteiner & Weiner
  3. Landsteiner & Levine
  4. Weiner & Levine

Answer: (1) Tjio & Levan

Explanation: Joe Hin Tjio and Albert Levan, discovered that the number of chromosomes (karyotype) in humans was 46 chromosomes, 23 each gender. The finding was established in December 1955.

18. Crossover occurs during

  1. Prophase of mitosis
  2. Prophase I of meiosis
  3. Prophase II of meiosis
  4. Prophase I and II of meiosis

Answer: (2) Prophase I of meiosis

Explanation: Crossover is a process in which homologous chromosomes trade parts. It occurs at Prophase I of meiosis when homologous pair appear as a Tetrad (also called Pachytene).
-> Point of crossover appears as chiasmata (singular-chiasma) as homologous chromosomes tend to separate (Diplotene).
Read More: In meiosis, how does prophase I differ from prophase II?

19. Regions of chromosomes that are transcriptionally active are known as

  1. Euchromatin
  2. Chromatin
  3. Telomere
  4. Centromere

Answer: (1) Euchromatin

Explanation: During most of a cell’s life cycle, the chromosomes exist in an unraveled
a linear form that can be transcribed to code for proteins.

-> Region of chromosomes that are transcriptionally active is known as euchromatin.
● These chromosomes undergo normal chromosome condensation and decondensation
during the cell cycle.
● These regions account for most of the genome and lack repetitive DNA.

-> The transcriptionally inactive portions of chromosomes, such as centromeres, are
heterochromatin regions and remain condensed throughout the cell cycle.
● These chromosomes are generally not sequenced due to complex repeat patterns (repetitive DNA) that can be found at centromeres, much of the Y chromosome’s long arm, and the short arms of the acrocentric chromosomes.

20. In a DNA profile, null alleles arise as a result of:

  1. Allele drop out
  2. Allele drop in
  3. Low pH
  4. High pH

Answer: (1) Allele drop out

-> Null alleles: Also called silent alleles, is a nonfunctional allele caused by a failure in amplification during PCR reaction which could be due to a genetic mutation.
-> Allelic dropout (ADO): is a common phenomenon, that usually occurs when DNA is inadequate. It happens when one allele may be preferentially amplified over other (or one allele has insufficient amplification). It was first described in 1991 with the term “partial amplification failure”.
-> Allelic Drop-in (ADI): is seen when a small number of low STR alleles appear that are not derived from the donor sample to the profile. It occurs because of sporadic contamination events.

21. Which of the following parts of a firearm is the most appropriate to collect ‘contact DNA’ of the shooter?

  1. Unfired bullet
  2. Barrel
  3. Trigger
  4. Chamber

Answer: (3) Trigger

Explanation: Trigger and shoulder stock/buttstock is the most preferential region from where shooter probably loses their DNA traces in form of sweat or blood.

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