UGC NET Exam June 2019 Forensic Science Paper-2 Question Paper with Answer Key & Explanation

81. Statement 1(S1): Luminol test is a confirmatory test for detection of blood.

Statement 2 (S2): Luminol added together with H2O2 (Hydrogen Peroxide) becomes luminescent in the presence of haemoglobin.

Choose the correct answer:

A. S1 and S2 both are correct and S2 is explanation of S1

B. S1 and S2 both are correct and S2 is not correct explanation of S1

C. S1 is false and S2 are true

D. Both are false

Ans.- C. S1 is false and S2 are true

Explanation:

Luminol Test is a Presumptive Test for Blood detection. The luminol solution contains both luminol (C8H7N3O2) and hydrogen peroxide (H2O2). The hydrogen peroxide reacts with the iron in blood to produce oxygen, then oxygen then reacts with the luminol, changing the structure of the molecule and temporarily adding energy, which produce light.

82. ‘Disulfiram’ is used for treatment of chronic alcohol abuse acts by:

i. Increasing the concentration of acetaldehyde

ii. Blocking aldehyde dehydrogenase

iii. Increasing the concentration of acetic acid

iv. Blocking acetate dehydrogenase Choose the correct answer

A.  iii and ivB. i and iv
C. i and iiD. ii and iii

Ans.- C. i and ii

Explanation:

The enzyme alcohol dehydrogenase in the liver and brain converts alcohol into acetaldehyde. The enzyme aldehyde dehydrogenase (ALDH) oxidizes the acetaldehyde byproduct into acetic acid. Disulfiram inhibits this oxidation by inhibiting ALDH, causing rapid development of acetaldehyde in the blood upon consumption of alcohol. The result is called the disulfiram – alcohol reaction, and it can increase the concentration of acetaldehyde in the blood by 5 to 10 times that occurring without disulfiram.

83. The net retardation of projectile due to air resistance is given by:

A. AVnB. ½ gt2
C. t xV cos ED. 4r-1/7

Where ‘A’ and ‘n’ are constant that vary for different velocity zones ,’V’ is the velocity of the projectile , ‘g’ is the acceleration due to gravity , ‘t’ is the time taken by projectile, ‘E’ is the angle of deviation and ‘r’ the ogival radius in calibers.

Ans.- A. AVn

84. Which type of neutron is most suitable for NAA technique?

A. Very low energy neutronB. Cold neutron
C. Thermal neutronD. High energy neutron

Ans.- C. Thermal neutron

85. Match List-1 with List2

List-1List-2
a. RFLPi. Heteroplasmy
b. STRii. Southern blotting
c. mt-DNAiii. Paternal lineage
d. Y-STRiv. Multiplexing

Choose the correct option from those given below:

A.a- ivb- ic- iid- iii
B.a- ib- iiic – ivd- ii
C.a. iib- ivc- id- iii
D.a. iiib- iic- ivd- i

Ans.- C.

86. ANFO stands for:

A. Ammonium Nitrite Fuel OilB. Ammonium Nitrate Fuel Oil
C. Ammonium Nitride Fuel OilD. Ammonium Nitroglycerine Fuel Oil

Ans.- B. Ammonium Nitrate Fuel Oil

87. Aluminum, calcium, magnesium and cobalt are components of:

A. Red colour safety glassB. Blue colour safety glass
C. Yellow colour safety glassD. Green colour safety glass

Ans.- B. Blue colour safety glass

88. Statement 1 (S1):- Cement is made by mixing together calcareous and argillaceous material at high temperature.

Statement 2 (S2):- Property of cement depends on various phase composition of clinker and on the structure of individual crystal phase.

Choose the correct answer:

A. Both are CorrectB. Both are wrong
C. S1 correct, S2 wrongD. S1 wrong, S2 correct

Ans.- A. Both are Correct

89. Which of the following is used to analyze for the presence of ‘Gun-Shot-Residue’?

A. Micro spectrophotometryB. Refractive Index measurement
C. Polarized light MicroscopyD. Scanning Electron Microscopy coupled with energy dispersive X-ray analyzer

Ans.- D. Scanning Electron Microscopy coupled with energy dispersive X-ray analyzer

Explaining:

Scanning electron microscopes can observe individual characteristics of each particle.  This can link lead (Pb), barium (Ba), and antimony (Sb) to a single particle, which can determine if  the elements are unique or consistent with gunshot residue. 

90. In trap cases, the pink colour of ‘Phenolphthalein’ fades due to:

A. Complex with Na2CO3B. 2 (4-hydroxybenzoyle) benzoic acid and phenol
C. TrichlorophenolphthaleinD. Phenolic anhydride

Ans.- B. 2 (4-hydroxybenzoyle) benzoic acid and phenol

Explanation:

Colour of phenolphthalein fades due to its breaking down into 2 (4-hydroxybenzoyl) benzoic acid and phenol in alkali medium. The chemical break down of the alkaline phenolphthalein is caused by the oxygen present in the air.