Note: For systematic learning, you can check the index page of the Instruments in Forensic Science. Here, we listed all the MCQs based on the NTA UGC syllabus.
1. Technique based on the differential rate of migration of analytes through a buffered medium for the quantitative and qualitative determination of ionic compound is known as:
- Electrophoresis
- Chromatography
- Spectrometry
- Distillation
Answer and Explanation
Answer: (1) Electrophoresis
2. Match the instruments with the material analyzed:
| Instrument | Material |
| (a) Electron microscope | (i) Bullet |
| (b) Electrophoresis | (ii) Alcohol |
| (c) GLC | (iii) Hair |
| (d) Comparison Microscope | (iv) Blood |
| (a) | (b) | (c) | (d) | |
| 1. | (iii) | (iv) | (ii) | (i) |
| 2. | (i) | (ii) | (iv) | (iii) |
| 3. | (ii) | (i) | (iii) | (iv) |
| 4. | (iv) | (iii) | (ii) | (i) |
Answer and Explanation
Answer: (1) (iii), (iv), (ii), (i)
Explanation:
-> Electron Microscope: They have high magnification and resolution power so they are used in hair and fiber analysis.
-> Electrophoresis: based on the migration of charged particles to the respective ends, they can be used for the separation of protein in the blood.
-> GLC: They are used for analyzing volatile compounds such as alcohol.
3. Which of these techniques is used to separate serum?
- GLC
- PCR
- Electrophoresis
- Both (2) and (3)
Answer and Explanation
Answer: (3) Electrophoresis
4. Which one of the following statements is true about the migration of biomolecules in electrophoresis?
- The rate of migration is directly proportional to the resistance of the medium
- Rate of migration is directly proportional to the current
- Low voltage is used for separation of high mass molecules
- Rate of migration is inversely proportional to the current
Answer and Explanation
Answer: (2) Rate of migration is directly proportional to the current
5. At pH 6 glycine behaves as
- Anion
- Cation
- Zwitterion
- Inorganic ion
Answer and Explanation
Answer: (3) Zwitterion
Explanation: Zwitterions are molecules or ions having separate positively and negatively charged functional groups.
6. Gel electrophoresis is useful in the identification of the following:
- Blood
- Alkaloids
- Insecticides
- All the above
Answer and Explanation
Answer: (1) Blood
Explanation: Gel Electrophoresis is a technique that is used to isolate, identify, and characterize the properties of DNA fragments in many different situations. That ‘s why the correct option is blood because (in the options) blood is the only component that is used to isolate the DNA.
7. In high voltage electrophoresis, increasing the voltage applied to the electrophoretic plates extend the separation capabilities to the substance with :
- Low molecular weight
- High molecular weight
- Equal molecular weight
- None of the above
Answer and Explanation
Answer: (1) Low molecular weight
Explanation: Lower molecular weight tends to be more moveable. Hence, when the voltage at the electrophoretic plates increases, the lower molecular weight substances such as amino acids, peptides, indoles, sugars, purines, pyrimidines, amines, and inorganic ions move faster and increase the rate of separation.
8. Match the following:
| List-I | List-II |
| (a) Gel electrophoresis | (i) Examination of synthetic fiber |
| (b) Polarising Microscope | (ii) Matching of firing pin mark |
| (c) Atomic Absorption Spectroscopy | (iii) Enzyme typing |
| (d) Comparison Microscope | (iv) Estimation of metals |
| (a) | (b) | (c) | (d) | |
| 1. | (i) | (ii) | (iii) | (iv) |
| 2. | (iii) | (i) | (iv) | (ii) |
| 3. | (iv) | (iii) | (ii) | (i) |
| 4. | (ii) | (iv) | (iii) | (i) |
Answer and Explanation
Answer: (2) (iii), (i), (iv), (ii)
9. PGM, ESD, and GLO-I enzymes can be analyzed on a single plate by
- Single system of electrophoresis
- Multi-system of electrophoresis
- Thick gel electrophoresis
- None of the above
Answer and Explanation
Answer: (1) Single system of electrophoresis
10. Different dye constituents of ink can be separated with the help of
(i) TLC (ii) VSC (iii) Electrophoresis (iv) ESDA
- (i) and (ii) are correct.
- (ii) and (iii) are correct.
- (i) and (iii) are correct.
- (i) and (iv) are correct.
Answer and Explanation
Answer: (3) (i) and (iii) are correct
Explanation: -> TLC is one of the most common types of techniques that are used to separate different ink constituents.
> Electrophoresis can also be used for separating dye constituents (rarely used).
Reference: The Identification of Inks by Electrophoresis
11. Serum protein polymorphism are demonstrated by
- HPLC
- Centrifugation
- GC-MS
- Electrophoresis
Answer and Explanation
Answer: (4) Electrophoresis
Explanation: Human serum contains many proteins, many of which show polymorphism. Common Serum proteins are:
-> Serum Haptoglobins (Hp): most widely used serum protein for forensic purposes. They have two alleles (Hp1 and Hp 2) that from three genotypes (Hp-, Hp2-2, Hp1-2/Hp2-1).
-> Group-specific component (Gc): three different forms i.e. Gc-1-1, Gc-2-2. and Gc-3-3
-> Ag Group: two alleles Ag (x) and Ag(y).
-> Gm and km systems: highly polymorphic and have a high concentration in dried blood because they are quite stable to heat. Gm has 20 allotypes while Km has 3.
-> Most of the human serum proteins are extracted using electrophoresis and isoelectric focusing (IEF).
-> Isoelectric Focusing is used mainly to separate proteins for analysis or purification.
Reference: Essentials of Forensic Medicine and Toxicology by Anil Aggrawal
12. Conventional electrophoretic techniques resolve allelic products of PGM locus into one of these phenotypes:
- 1, 1-2 and 2
- 1, 1-1 and 2
- 1, 2-2 and 2
- 2, 1-1 and 1
Answer and Explanation
Answer: (1) 1, 1-2 and 2
Explanation: There are three genetic loci that control PGM polymorphism
-> Locus 1 is on chromosome 1 (forensically important)
-> Locus 2 is on chromosome 4
-> Locus 3 is on chromosome 6
-> Conventional electrophoretic techniques for PGM activity routinely detect 3 phenotypes PGM 1, PGM 2,and PGM 2-1.
-> Newer Isoelectric Focusing (IEF) method of PGM analysis can detect 10 phenotypes: PGM 1+, PGM 1–, PGM 1+1–, PGM 2+, PGM 2–, PGM 2+2–, PGM 2+1–, PGM 2+1+, PGM 2–1+, and PGM 2–1–.
13. In capillary electrophoresis, which flow causes the movement of electrolytes through the tube?
- Micro-osmatic flow
- Electro-osmatic flow
- Macro-osmatic flow
- None of the above
Answer and Explanation
Answer: (2) Electro-osmatic flow
Explanation: Electro-osmotic flow is defined as the motion of liquid that is induced by an applied electric potential at the ends of the capillary tube in capillary electrophoresis.
14. In an SDS-PAGE:
- Proteins are denatured by SDS
- Proteins have the same charge to-mass ratio
- Smaller proteins migrate more rapidly
- All of the above
Answer and Explanation
Answer: (4) All of the above
Explanation: SDS-PAGE acronym for Sodium Dodecyl Sulfate–Polyacrylamide Gel Electrophoresis which is an electrophoresis method that allows protein separation by masses that is governed by the charge to mass ratio.
15. In capillary electrophoresis the internal diameter of fused-quartz capillary ranges between:
- 50 to 150 nm
- 20 to 100 µm
- 5 to 15 mm
- 1 to 2 cm
Answer and Explanation
Answer: (2) 20 to 100 µm
Explanation: Fused silica capillaries are almost universally used in capillary electrophoresis.
-> Internal diameter: 20 to 200 µm
-> Outside diameter: 150 to 360 µm
-> Length: 20 to 100 cm.
-> Optimum Internal diameter for best sensitivity and capacity is achieved by a large internal diameter. A capillary diameter of 50 µm is optimal for most applications but a diameter of 75 to 100 µm is needed when higher sensitivity.
-> Increasing diameter above 75 µm causes poor heat dissipation and requires low-conductivity buffer and low field strengths to avoid excessive Joule heating.
Reference: Capillary Electrophoresis of Proteins Pg 57
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