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1. Which of the following can distinguish human salivary amylase and human pancreatic amylase?

  1. Starch-iodine assay
  2. Phadebas assay
  3. RNA based assay
  4. Use of anti-human salivary amylase antibodies

Answer: (3) RNA based assay

2. Phase 1 oxidation reactions are catalyzed by which of the following?

  1. FMOs
  2. GSTs
  3. CYPs
  4. NATs

Answer: (3) CYPs

Explanation: Cytochromes P450 (CYPs)

3. The situation in which a gene at one locus alters the phenotypic expression of a gene at another locus is known as

  1. Dominance
  2. Codominance
  3. Pleiotropy
  4. Epistasis

Answer: (4) Epistasis

Explanation: Epistasis: Interaction of genes that are not alleles, in particular, suppression of the effect of one gene by another.
-> Example: A gene for total baldness would be epistatic to one for blond hair resulting in a baldness phenotype that supersedes genes for hair color, and so the effects are non-additive.

4. The possible Multi Enzymes System (MES) among the following is

  1. PGM, ESD, GLO
  2. PGM, ADA, GLO
  3. PGM, AK, GLO
  4. ESD, ADA, AK

Answer: (1) PGM, ESD, GLO

Explanation: There is a lot of research on Multiple Enzyme Systems (MES), in which more than one polymorphic enzyme or protein is determined in one and the same electrophoretic run.
Some typical combinations of Multi Enzymes System (MES) are:
-> By Wraxall and Stolorow (1978), uses PGM, ESD, and GLO on one plate.
-> Another MES setup is PGM, ADA, and AK.

5. Identify the correct sequence in which techniques of DNA analysis have been developed:

A. D1S80
D. mtDNA

Choose the correct answer from the options given below:

  1. A, B, C, D
  2. B, C, A, D
  3. B, A, C, D
  4. C, A, B, D

Answer: (3) B, A, C, D

-> HLA-DQ: The first PCR product for forensic analysis by PCR was introduced in 1986 i.e.e HLA DQ alpha.
-> D1S80: Nakamura, Y., et al. (1988), Isolation and mapping of polymorphic DNA sequence (pMCT118) on chromosome 1p (D1S80).
-> First STR kit: 1991, first useful polymorphic human STRs have been identified.
-> mtDNA: 1992, first application of mtDNA in casework (UK).
Read More: History and Development of Forensic Biology and DNA Analysis

6. Which of the two statements are true for the “Stochastic effect”?

(a) It happens when amplifying a very low level of template DNA
(b) It holds true for monozygotic alleles
(c) It is relevant for one of the two alleles of a heterozygote that fail to be detected
(d) It holds true for a large quantity of template DNA

Choose the correct option

  1. (a) and (b)
  2. (c) and (d)
  3. (a) and (c)
  4. (b) and (d)

Answer: (3) (a) and (c)

-> Stochastic (random) effect in DNA analysis is defined as the variation is a fundamental physical law of the PCR amplification process when examining low amounts of DNA.
-> With a heterozygous locus (two alleles are present), unequal sampling of the alleles can result in failure to detect one or both of the alleles. In that case, stochastic effects are seen as the fluctuation that has different alleles that are amplified from the same DNA extract.
-> This means that amplification of the same DNA extract can lead to two different alleles.

7. The expression of which of the two RT-PCR based analyses can be used for the identification of saliva

(a) Kallikrein 3 (b) B-spectrin (c) Histatin 3 (d) Statherin

Choose the correct option

  1. (a) and (d)
  2. (b) and (d)
  3. (a) and (c)
  4. (c) and (d)

Answer: (4) (c) and (d)

Explanation: Juusola and Ballantyne (2003) isolated mRNA from blood, semen, and saliva stains and used it for RT-PCR analysis. Specifically to saliva, they study saliva-specific genes such as statherin, histatin 3, PRB1, PRB2, and  PRB3. 

8. RFLP (Restriction Fragment Length Polymorphism) analysis determines which of the following?

A. Power of discrimination (Pd)
B. Variation in the length of a defined fragment of DNA
C. Hundreds of variations at each locus
D. Age of Bloodstain

Choose the most appropriate answer from the options given below:

  1. D, A and C only
  2. B, D and C only
  3. A, B and C only
  4. A, D and B only

Answer: (3) A, B, and C only

9. Assertion (A): Existence of heteroplasmy is one of the biggest problems of working with mtDNA.

Reason (R): Heteroplasmy is the most likely result of the errors or mutations that happen during mt DNA.

  1. Both (A) and (R) are true and (R) is the correct explanation of (A)
  2. Both (A) and (R) are true and (R) is not the correct explanation of (A)
  3. (A) is true but (R) is false
  4. (A) is false but (R) is true

Answer: (1) Both (A) and (R) are true and (R) is the correct explanation of (A).

Explanation: Heteroplasmy is described as the situation in which two or more mtDNA variants exist within the same cell. They are usually seen because of mutation.

10. The principle of radio-immunoassay is based on the interaction of:

  1. Unlabelled antigen with a fixed amount of corresponding labeled antigen and antibody
  2. Labelled antigen with a variable amount of antibody
  3. Unlabelled antigen with a variable amount of antibody
  4. Variable amount of both labeled antigen and antibody

Answer: (1) Unlabelled antigen with a fixed amount of corresponding labeled antigen and antibody

11. The technique used in the identification of saliva is based on the detection of specific types of mRNA expressed exclusively in certain cells in the oral cavity using one of these techniques.

  1. PCR
  2. RT-PCR
  3. Sequencer
  4. Gel-documentation

Answer: (2) RT-PCR

Explanation: RNA-based assay can be used in the identification of saliva using the Reverse Transcriptase Polymerase Chain Reaction (RT-PCR) method to detect gene expression levels of mRNAs. Two genes for this purpose is:
-> Gene Histatin 3 (HTN3): Histidine-rich protein involved in nonimmune host defense in the oral cavity.
-> Statherin (STATH) is an inhibitor of the precipitation of calcium phosphate salts in the oral cavity.

12. Which of the following can be detected through radioimmunoassay?

A. Metals
B. Toxicants
C. Drugs
D. Antigens

Choose the Correct answer from the options given below:

  1. A, B and C only
  2. A, B and D only
  3. A, C and D only
  4. B, C and D only

Answer: (4) B, C and D only

Explanation: Radioimmunoassay is a technique for determining antibody levels with the use of labeled radioisotope antigens in biological samples.

13. Enzyme that is used to join DNA fragments

  1. DNA- Topoisomerase
  2. DNA Ligase
  3. DNA Polymerase
  4. Reverse transcriptase

Answer: (2) DNA Ligase

Explanation: DNA ligase is a DNA-joining enzyme. If two pieces of DNA have matching ends, ligase can link them to form a single, unbroken molecule of DNA.
-> It is necessary for all entities to sustain the structural integrity of the genome

14. Which of the following conditions is an X‐linked condition?

  1. Haemophilia
  2. Huntington’s disease
  3. Cystic fibrosis
  4. Sickle cell anaemia

Answer: (1) Haemophilia

Explanation: Hemophilia is a sex-linked recessive disorder with an abnormal gene carried on the X chromosome.
-> It is also called X-linked recessive hereditary disorder.
-> Affects males due to the presence of only one X chromosome.
-> Complete androgen insensitivity syndrome (cAIS), formerly known as testicular feminization syndrome (a common form of male pseudohermaphroditism), is an X-linked recessive condition characterized by failure of normal masculinization of the external genitalia in genetically male (XY) individuals.

15. Statement (S1): Bovine Serum Albumin (BSA) is added to the PCR mixture to reduce the effect of PCR inhibitors.

Statement (S2): BSA acts as a binding site for PCR inhibitors.

  1. Both S1 and S2 are true and S2 is the correct explanation of S1
  2. Both S1 and S2 are true, but S2 is not the correct explanation of S1
  3. S1 is true but S2 is false
  4. S1 is false but S2 is true

Answer: (1) Both S1 and S2 are true and S2 is the correct explanation of S1

-> Bovine Serum Albumin (BSA) is one the most commonly used to overcome the inhibition effects and is added during the extraction process in PCR and ELISA (especially in the case of phenolic compounds).
-> Other chemicals that reduced the effect of inhibitors are:
● Polyvinylpolypyrrolidone (PVPP)
● Skim milk
● Sodium sulfite
● Dimethyl sulfoxide

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