| Post Name | SCIENTIFIC OFFICER (Chemical Examiners Laboratory Department) |
|---|---|
| Question Paper Code | 175/2025 |
| Category Code | 185/2025 |
| Date of Test | 30 December 2025 |
| Medium of Question | ENGLISH |
| Exam Type | OMR Examination |
| Total Questions | 100 |
1
Which glycosidic linkage is typical of animal glycogen?
Answer
B. Ξ± β 1,4 with Ξ± β 1,6 branching
2
Which analytical technique is most commonly used to determine the secondary structure
content of proteins?
Answer
C. Circular Dichroism
3
The optical rotation of amino acids arises from :
Answer
A. The Ξ± β carbon being chiral
4
In fluorescence microscopy, why does the light emitted by a fluorophore have a longer
wavelength than the light used for excitation?
Answer
B. Stokes shift due to energy loss in the excited state
5
In agarose gel electrophoresis, the migration distance of linear DNA fragments decreases
as the fragment size increases. Since electrophoretic mobility is approximately inversely
proportional to the logarithm of DNA fragment length (in kb), what happens to the
mobility when the fragment size is doubled?
Answer
D. Mobility decreases by approximately a constant factor (βΌlog2)
3 A
6
In a PCR reaction, you accidentally omitted Mg2+from the reaction buffer. What is the
most likely outcome?
Answer
B. The DNA polymerase will have reduced activity or fail to extend.
7
Which of the following amino acids is most likely to be found in the interior of a globular
protein?
Answer
D. Leucine
8
A patient with chronic liver disease shows elevated AST, ALT, and GGT, with AST/ALT
ratio > 2. This pattern is most characteristic of :
Answer
B. Alcoholic liver disease
9
The biological value
Answer
C. Proportion of essential amino acids and their utilization
10
The predominant metabolic adaptation in marasmus is :
Answer
C. Enhanced lipolysis and ketone body production for energy
11
A child presents with chronic diarrhea, steatorrhea, abdominal distension, and poor
weight gain. Duodenal biopsy shows villous atrophy. Which condition is most likely?
Answer
C. Celiac disease
12
Rifampicin acts by :
Answer
B. Blocking bacterial RNA polymerase and inhibiting transcription
13
During severe hypoxia, which change in hemoglobin β oxygen dissociation curve and
metabolic parameter is MOST characteristic?
Answer
C. Shift to the right with increased H+ and 2,3- BPG (2,3-biphosphoglycerate)
14
In nephrotic syndrome, which of the following plasma proteins shows the greatest
proportional increase as a compensatory hepatic response?
Answer
C. Ξ±2-macroglobulin
15
Which of the following B vitamins is not correctly matched with its role in the citric acid
cycle?
Answer
D. Pyridoxine
16
Which of the following statements about the reciprocal regulation of glycogen synthase
and glycogen phosphorylase is correct?
Answer
C. One of the kinases that phosphorylates glycogen synthase is phosphorylase
kinase, which is Ca2+/calmodulin-dependent, contributing to inactivation of
synthesis when breakdown is promoted.
17
Which of the following metabolic disorders correctly matches the toxin or defect with its
biochemical consequence?
Answer
C. Refsum disease β accumulation of phytanic acid because of a defect in
peroxisomal ο-oxidation; leading to neuro symptoms like ataxia and retinitis
pigmentosa.
18
Which of the following statements is correct regarding the cyclooxygenase
Answer
B. Cyclooxygenase is a suicide enzyme.
19
A patient presents with elevated plasma tyrosine, liver failure, and elevated
succinylacetone on newborn screening. Which of the following enzyme defects is most
likely responsible?
Answer
C. Fumary lacetoacetate hydrolase
20
In Lesch β Nyhan syndrome, deficiency of hypoxanthine-guanine phosphoribosyl-
transferase (HGPRTase) leads to hyperuricemia. Which of the following best explains
why PRPP level rise in this condition, contributing to purine overproduction?
Answer
B. Due to HGPRTase deficiency, feedback inhibition of PRPP amidotransferase
by IMP and GMP decreases, increasing PRPP production.
21
In the mitochondrial electron transport chain, which of the following statements is
correct?
Answer
C. Coenzyme Q (ubiquinone) is a mobile electron carrier that accepts electrons
from both Complex I and Complex II.
22
Which of the following statements best describes allosteric regulation?
Answer
C. Allosteric effectors bind at a regulatory site distinct from the active site and
can influence enzyme kinetics by changing either Km, Vmax, or both.
23
Which of the following statement is / are CORRECT about EPIGENETICS
(i) Currently, there are three major types of epigenetic modifications:
(1) DNA methylation,
(2) Histone modification and
(3) noncoding RNAs.
(ii) DNA methylation is as well-known epigenetic change. Methylation of Adenine
occurs frequently; Cancer is the most common human disease associated with
aberrant DNA modification.
(iii) Noncoding RNAs also function in the regulation of translation. In addition to
noncoding ribosomal and tRNAs, there are many forms of noncoding RNA,
including long (> 200 nucleotides) and short (20-200 nucleotides) noncoding RNAs
Answer
C. only (i) and (iii)
24
Which of the following statement is / are CORRECT about Flow cytometry?
(i) This is the fluorescence technique used to identify and enumerate cells bearing a
particular antigen(s) or the surface markers by suspending them in a stream of
fluid and passing them through and electronic detection apparatus.
(ii) It allows simultaneous multiparametric analysis of the physical and / or chemical
characteristics of up to thousands of particles per second.
(iii) Different populations of molecules can be differentiated by charge using forward
and right-angle light scatter.
Answer
A. only (i) and (ii)
25
Which of the following statement is / are CORRECT about artificial active immunity?
(i) Artificial active immunity is the resistance induced by vaccines.
(ii) Vaccines are preparations of live or killed microorganisms or their products used
for immunisation.
(iii) Live vaccines initiate infections without causing any injury or disease. The
immunity caused by live vaccines lasts for several years but booster doses may be
necessary.
Answer
D. All of the above (i), (ii) and (iii)
26
Which of the following statement is / are INCORRECT Primary immunodeficiency
syndrome?
(i) The primary immunodeficiency may be due to humoral immunodeficiency
Answer
B. cell
defects}, cellular immunodeficiency {T cell defects} or combined immunodeficiency
27
Which of the following statement is / are CORRECT about MICRO RNA?
(i) The number of bases in micro RNA is 50 β 70.
(ii) They have RNA hairpin structure and are called short hairpin RNA.
(iii) These are transported through nuclear pores into the cytoplasm, where out of the
two stands, one is broken by dicer nuclease.
Answer
B. only (ii) and (iii)
28
Which of the following statement is / are INCORRECT about inhibitors of translation in
Bacteria?
(i) Tetracycline inhibits the peptidyl transferase activity of bacterial ribosomes.
(ii) Erythromycin bind to the 30S subunit of the bacterial ribosome and so inhibit
attachment of amino acyl tRNA to the A site of ribosomes.
(iii) Chloramphenicol prevents the translocation process.
Answer
D. All of the above (i), (ii) and (iii)
29
Which of the following statement is / are CORRECT about Repair of DNA?
(i) In Nucleotide excision-repair mechanism is used to replace regions of damaged
between two GATC sequences.
(ii) Faulty mismatch repair has been linked to hereditary non-polyposis colon cancer
{HNPCC}
(iii) In Base excision-repair, specific enzymes recognize a depurniated site and replace
the appropriate purine directly, without interruption of the phospho-diester
backbone
Answer
B. only (ii) and (iii)
30
Which of the following statement is / are CORRECT hypersensitivity reactions?
(i) In Type I hypersensitivity reactions, the antigen combines with the cell-fixed
antibody, leading to release of pharmacologically active substances.
(ii) In Type II hypersensitivity reaction, the damage is caused by antigen antibody
complexes. These may precipitate in and around small blood vessels, causing
damage to cells secondarily, or on membranes, interfering with their function.
(iii) In Type IV hypersensitivity reaction, is a cell-mediated response. The antigen
activates specifically sensitised CD4 and CD8 T cells, leading to the secretion of
lymphokines and phagocyte accumulation.
Answer
C. only (i) and (iii)
31
For a low-spin octahedral d5 complex, which electronic transition is Laporte-allowed but
spin-forbidden?
2
Answer
Question Cancelled
32
Which of the following organometallic fragments is NOT isolobal with methyl] radical?
Answer
Question Cancelled
33
A Ο -cyclopentadienyl (Ξ· β Cp)
5
complex of a Group-6 metal shows a
temperature-dependent NMR pattern that collapses from 10 signals to 2 signals at
320 K. What fluxional process is most consistent?
Answer
B. Ring-whizzing (Ξ· 5 β Ξ·1 β Ξ· 3 interchange)
34
The most stable sulphur-nitrogen compound among the following is :
Answer
B. S4N 4
35
A crystal shows strong reflections only when h, k, l are either all even or all odd. The
Bravais lattice is :
Answer
C. Face-centered cubic
36
Inverse spinel Fe3O4 has :
Answer
C. Fe3 + in tetrahedral, Fe2 + and Fe3 + in octahedral
37
The photoconductivity of a solid increases sharply when irradiated with photons of
energy slightly above the band gap because :
Answer
A. Carrier concentration increases exponentially
38
Atropisomerism results from :
Answer
C. Restricted rotation around a single bond
39
The two Ξ± -hydrogen atoms in 3-chlorobutanoic acid are :
Answer
C. diastereotopic
40
Thermal electrocyclic ring closure of (2E, 4Z 6K)-octatriene gives :
Answer
B. cis-5,6-dimethyl-1,3-cyclohexadiene
41
When a photo excited ketone is treated with an alkene an oxetane is produced. This
reaction is known as :
Answer
A. Paterno-Buchi reaction
42
The C=O stretching vibration for acetyl chloride occurs approximately at :
Answer
A. 1800 cmβ»ΒΉ
43
An organic compound shows a 13C NMR chemical shift value above 200 ppm. The
compound is most probably a/an :
Answer
A. Carbonyl compound
44
What is the product formed when erythro dl pair of 3-bromo-2-butanol is treated with
HBr?
Answer
B. Meso-2,3-dibromobutane
45
How many radial and angular nodes are possible for 4d orbital?
Answer
B. 1 radial nodes and 2 angular nodes
46
Which statistics is commonly applied for dilute systems?
Answer
A. Maxwell-Boltzmann
47
Which among the following statements are correct regarding transition moment integral β« Ο_i pΜ Ο_f dΟ? (i) The ground state Ο_i need not be totally symmetrical. (ii) The magnitude of transition moment integral for allowed transition must be non zero. (iii) For MW spectra, the transition moment operator is the dipole moment vector. (iv) If the direct product representation of transition moment integral is obtained as Bβ, i.e. β« Ο_i pΜ Ο_f dΟ = Bβ in Cβv point group, it is considered as an allowed transition.
Answer
C. (ii), (iii)
48
How many ESR lines are possible for 1, 4-Benzosemiquinone radical anion?
Answer
B. 5
49
Which of the following statements are correct about Mossbauer spectra?
(i) Isomer Shift depends on 5 electron density of the excited and ground state nuclei.
(ii) Quadrupole splitting does not occur for symmetrical field gradient at the nucleus.
(iii) Doppler effect and recoil energy are not affecting Mossbauer spectra.
(iv) The energy of the Ξ³ -ray must be ideally between 100 β 1000 keV
Answer
D. (i), (ii)
50
The expression for mean free path of a molecule is :
K bT K bT
Answer
A. 2
51
Among the following methods, which one is suitable for studying the kinetics of gas
phase fast reactions in which wall effects interfere?
Answer
B. Shock tube method
52
For the reaction between S2O32β and Iβ ion, which statements are correct?
(i) Rate constant increases with increases in ionic strength
(ii) Rate constant decreases with increases in ionic strength
(iii) Rate constant is independent of ionic strength
(iv) Volume of activation for this reaction is negative (βve)
Answer
C. (i), (iv)
53
In neutron activation analysis, the primary radiation detected is :
Answer
C. Gamma rays
54
The function of a supporting electrolyte in polarography is to suppress :
Answer
B. Migration current
55
The technique in which the emission of photons from analytes are brought to an excited
state by the use of high energy plasma is :
Answer
A. ICP AES
56
When the number of theoretical plates is large, the column will be more?
Answer
B. efficient
57
Which thermal method is used to study difference in temperature of reference and
sample, measured as a function of same applied temperature?
Answer
C. DTA
58
In analytical chemistry, a coulometer measures the :
Answer
D. quantity of electricity required for a chemical change of the analyte
59
A voltammetric technique in which current is measured as a function of time at constant
potential is :
Answer
A. Amperometry
60
The most widely used signals in SEM are from :
Answer
D. Secondary electrons
61
Which historical development significantly improved the accuracy of suspect
identification in the early twentieth century?
Answer
C. Discovery of fingerprint individuality
62
______________ courts function as Mahila courts.
Answer
B. Additional Sessions courts
63
In the context of Locardβs principle of exchange, which of the following scenarios most
accurately demonstrates a secondary transfer that can still be considered significant
evidence during reconstruction of crime scene?
Answer
D. A victimβs hair found on the upholstery of a taxi that the suspect boarded
after fleeing the crime scene
64
Which Forensic Laboratory in India is uniquely placed under the CBI instead of the
ministry of Home Affairs?
Answer
B. CFSL Delhi
65
Which one of these is a search method particularly suited for complex crime scenes
where fine trace evidence might be missed by visual inspection?
Answer
D. Alternate light source
66
During microscopic examination of a hair sample, a forensic scientist observes pigment
granules that vary in shape, size and distribution along the shaft. Which structural layer
is being analyzed and why is it critical for forensic comparison?
Answer
C. Cortex: because its pigment granules provide individualized color and pattern
characteristics
67
Which of the following statements about forensic soil evidence is false?
Answer
A. All soils are chemically identical in a given region, so differentiation is
impossible
68
Which instrumental technique is most definitive for identifying the chemical composition
of individual layers in a multilayered paint sample?
Answer
Question Cancelled
69
Correct statement regarding lip prints according to Suzuki and Tsuchihashi
classification:
Answer
B. Type II lip prints represents the branched grooves.
70
All the following statement are correct regarding adolescent dental age estimation
between 10 to 18 yrs.
(i) Demirjian method is based on eight developmental stages of calcification of seven
left mandibular permanent teeth.
(ii) Cameriereβs method is based on the relationship between age and the degree of
open apices in tooth roots.
(iii) Olze method is based on visual radiographic comparison of tooth development and
alveolar eruption on the right side of the jaw with standard figures
Answer
D. Only (i) and (ii)
175/2025 16 A
71
All are true regarding Bayardβs spots except:
Answer
C. It is pathognomonic of asphyxial death.
72
Incorrect statement regarding new amendments of sexual offense law in the Bharatiya
Nyaya Sanhita, 2023
Answer
A. Section 79 of BNS criminalizes disclosure of identity of the victims of sexual
offences.
73
All are true regarding Paraquat poisoning except:
Answer
D. It is a bipyridinium herbicide which causes miosis and cholinergic crisis.
74
Which among the following statement is/are false with respect to aconite poison?
(i) Aconite species contain diterpene
Answer
C. 20) and norditerpene
75
True statement regarding cocaine metabolism:
(i) Benzoylecgonine is a major metabolite produced by liver esterases and plasma
cholinesterase.
(ii) Benzoylecgonine assays may be successful in urine up to 2 to 3 days due to the long
elimination half-life.
(iii) Cocaine benzoylecgonine can be analysed in hair samples by GC-MS and RIA.
Answer
B. Only (ii) and (iii)
76
Incorrect statement with respect to analytical methods used in toxicology:
Answer
A. Enzyme mediated immunoassay technique (EMIT) works on the principle
that the amount of drug present is inversely proportional to the inhibition of
an enzyme-substrate reaction.
77
Which of the following statement is/are true with respect to classical signs of asphyxia?
(i) Tardieu spots are due to increased venous pressure in small venules and
arterioles.
(ii) Engorgement of right side of heart is due to diminished suction power of left
ventricle.
(iii) Increased fluidity of blood is due to fibrinolysis triggered by a surge of
catecholamines during the agonal period.
Answer
A. Only (ii) and (iii)
78
Features of early post-mortem changes in the eye after death is/are:
(i) Intraocular pressure becomes 10 mm Hg after 3 hours after clinical death.
(ii) Outline of optic disk becomes blurred within 6 hours after clinical death.
(iii) Tache noir formation within 30 minutes of death.
Answer
C. Only (i) and (ii)
79
All are true regarding βHarvard criteria 1969β to diagnose brain stem death, except:
Answer
B. Duration of testing of respiration is 6 minutes.
80
Which bone has highest sex determination accuracy?
Answer
D. Pelvis
81
Abrin, the toxin from Abrusprecatorius, causes:
Answer
A. Gastrointestinal haemorrhage and bowel oedema
82
All are true regarding carbamates poisoning, except:
Answer
B. Irreversible binding to acetyl choline esterase
83
Which sedative-hypnotic most commonly produces a bullous skin lesions?
Answer
B. Phenobarbital
84
Choose the incorrect statement regarding breath alcohol estimation:
Answer
D. Tidal air is the most accurate portion of expired air for breath alcohol
estimation.
175/2025 19 A
85
After seizure, a mobile device is kept in a βββββββββββ to avoid remote wiping, data
tampering, and network connectivity:
Answer
A. Faraday bag
86
Dynamic Host Configuration Protocol
Answer
D. HCP) was developed to provide automated IP
address assignments, reducing manual work for administrators. DHCP logs can show an
investigator exactly which βββββββββββ was assigned the IP address in question during
the specified time.:
87
The Viola-Jones algorithm is primarily used to detect βββββββββββ in biometrics.:
Answer
B. faces
88
The presence of VMWare virtual machine artifacts on a hard disk image is often
confirmed by identifying files such as the .vmdk (virtual hard drive for the guest
operation system) and the .vmem
Answer
B. ackup of the virtual machineβs paging file), what
does .vmss file depicts:
89
Brain and kidney have which LDH isoenzymes?
Answer
B. LDH3
90
Which is the most abundant and universally distributed unusual base present in t-RNA?
Answer
A. Pseudouridine
91
Prostaglandins are present in semen; which is derived from which fatty acids?
Answer
A. Arachidonic acid
92
Who stabilizes the helical structure of DNA and RNA, protecting genetic information
and enabling proper function?
Answer
C. Base stacking
93
A corpse was found in an open field. The first wave of insects from Calliphoridae family
were present and were actively ovipositing. These insects are most likely to be:
Answer
C. Blow flies
94
Which of the following statements are true regarding DNA barcoding of species?
(i) DNA barcoding has been shown to be particularly effective in identifying a wide
range of northern hemisphere bird species
(ii) In DNA barcoding, cytochrome oxidase I
Answer
B. (i) and (iii)
95
Of the methods used to remove numbers punched on metals, which of the following will
permanently remove all recoverable traces of original number?
Answer
D. Welding and Drilling
96
Which of the following are the essential components of Mac Naughtenβs Standard?
(i) The presence of psychopathology: disease of the mind, resulting in
(ii) A defect of reason, such that the person
(iii) Lacks knowledge concerning the nature, quality and/or wrongfulness of the act
(iv) There must be no evidence of planning or premeditation by the defendant before
the criminal act was committed.
Answer
A. (i), (ii) and (iii)
97
Which of the following strategies are found to be common for disguised handwriting but
not for disguised signatures?
(i) Greater pen stops and pen lifts
(ii) Unusual letter form
(iii) Change of slope
Answer
D. Only (i)
98
The formation of halo of ink around the character
Answer
A. (i), (ii) and (iii)
99
Which of the following problem generally arises while analyzing ink sample by Raman
spectrophotometer?
Answer
D. Occurrence of fluorescence signal
100
Which of the following water marking techniques gives a sharp edge definition?
(i) Wire mark.
(ii) Shaded mark
(iii) Mollete process
(iv) Embossed watermark
Answer
B. (i), (iii) and (iv)
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