← Combined Technical (NG)
Past Questions — 2026
PCR can be used to detect the genes in the organism responsible for drug resistance, EXAMPLE:
A)
Mec-A gene in S aureus (MRSA)
B)
-lactamases in ESBL
C)
Mex PM gene in P. aeruginosa
D)
FoxP3 gene in Streptococci
PCR is commonly used to detect specific resistance genes. In methicillin-resistant Staphylococcus aureus (MRSA), the key resistance determinant is the mecA gene, which encodes an altered penicillin-binding protein (PBP2a) that confers resistance to beta-lactam antibiotics.
Why (a) is correct:
- mecA is a well-known, specific genetic marker for MRSA.
- PCR detection of mecA is a standard method for confirming methicillin resistance.
Why the others are incorrect:
- (b) Beta-lactamase in ESBL is not a single specific gene name; ESBL resistance is usually due to specific genes such as blaTEM, blaSHV, or blaCTX-M.
- (c) “Mex PM gene” is not the standard named resistance gene typically cited for PCR detection in P. aeruginosa in this context.
- (d) FoxP3 is a regulatory gene associated with T-regulatory cells in humans, not a drug-resistance gene in Streptococci.
Therefore, the best answer is (a).
Which of the following medium is used for cultivation of malaria parasite :
A)
Diamond’s TYM medium
B)
NNN medium
C)
Cysteine peptone media
D)
RPMI 1640 medium
Malaria parasite (Plasmodium spp.) is cultivated in vitro using RPMI 1640 medium, commonly supplemented with serum and other additives for red blood cell culture. Therefore, option (d) is correct. The other media are used for different parasites: Diamond’s TYM medium is used for Trichomonas, NNN medium is used for Leishmania/Trypanosoma, and cysteine peptone medium is used for certain protozoa such as Entamoeba.
In biomedical waste management, yellow plastic bag contents should be treated by:
A)
Incineration
B)
Autoclave
C)
Land fill
D)
Microwaving
In biomedical waste management, the yellow bag/category is used for infectious and pathological waste such as human/animal anatomical waste, soiled waste, microbiology waste, etc. This type of waste is meant for destruction by incineration (or plasma pyrolysis/deep burial in permitted cases), not by autoclaving or microwaving as the primary answer in standard MCQs.
Why others are incorrect:
- (b) Autoclave: generally used for sterilizing certain infectious plastic/glass/metal sharps or recyclable contaminated waste, not the standard disposal method for yellow bag waste.
- (c) Land fill: not the primary treatment for yellow category biomedical waste.
- (d) Microwaving: used for disinfection of specific biomedical waste categories, but not the standard method for yellow bag contents.
Therefore, the correct answer is Incineration.
The ribosome is the site of:
A)
DNA replication
B)
Protein synthesis
C)
RNA sequencing
D)
Lipid synthesis
Ribosomes are the cellular organelles where proteins are made by translating mRNA into polypeptide chains. Therefore, the correct answer is protein synthesis. DNA replication occurs mainly in the nucleus, RNA sequencing is not a normal ribosomal function, and lipid synthesis occurs mainly in the smooth endoplasmic reticulum.
The protein coat surrounding the viral nucleic acid is called:
A)
Envelope
B)
Ribosome
C)
Capsid
D)
Mesosome
The protein coat that directly surrounds and protects the viral nucleic acid is called the capsid. It is made of protein subunits called capsomeres. An envelope is an outer lipid covering present only in some viruses and lies outside the capsid. Ribosomes are cell structures for protein synthesis and are not viral coats. Mesosome is a term formerly used for infoldings in bacterial plasma membrane, not a viral structure.
The temperature and pressure commonly used in an autoclave are:
A)
100°C at 15 psi for 10 min
B)
121°C at 15 psi for 15–20 min
C)
160°C for 2 hours
D)
120°C for 30 min
The standard sterilization condition for an autoclave is saturated steam at 121°C under 15 psi pressure for about 15–20 minutes. This combination is sufficient to kill vegetative cells, spores, and most microorganisms. Option (a) is incorrect because 100°C is the boiling point of water and is not enough for reliable sterilization in an autoclave. Option (c) refers to hot air oven sterilization, not autoclaving. Option (d) is incomplete because autoclave sterilization is defined by both temperature and pressure, and the standard accepted value is 121°C at 15 psi for 15–20 minutes.
Which of the following best defines an opportunistic infection?
A)
Infection caused by highly pathogenic organisms only
B)
Infection acquired in a hospital setting
C)
Infection occurring when normal defenses are weakened
D)
Infection transmitted through insect vectors
An opportunistic infection is one that occurs when the body's normal immune defenses are weakened, allowing ordinarily harmless or low-virulence microorganisms to cause disease. Therefore, option (c) is correct. Option (a) is incorrect because opportunistic infections are often caused by organisms that are not highly pathogenic in healthy individuals. Option (b) refers specifically to nosocomial or hospital-acquired infections. Option (d) describes vector-borne infections, which are transmitted by insects such as mosquitoes or flies.
The most common species causing invasive Aspergillosis is:
A)
Aspergillus flavus
B)
Aspergillus niger
C)
Aspergillus fumigatus
D)
Aspergillus terreus
Invasive aspergillosis is most commonly caused by Aspergillus fumigatus. It is the leading pathogenic species because its small airborne conidia can easily reach the alveoli, especially in immunocompromised patients. Aspergillus flavus can also cause disease but is less common than A. fumigatus. Aspergillus niger is more often associated with otomycosis and colonization, while Aspergillus terreus is a recognized cause of invasive disease but is less common. Therefore, option (c) is correct.
In a person who is fasting, the urine will contain:
A)
Little glucose
B)
Less urea
C)
Excess urea
D)
Little fat
During fasting, the body first uses stored glycogen and then begins breaking down proteins and fats for energy. Breakdown of proteins produces amino groups, which are converted into urea in the liver and excreted in urine. Therefore, urine in a fasting person contains excess urea. (a) Little glucose is incorrect because glucose is normally not present in urine unless blood sugar is abnormally high. (b) Less urea is incorrect because protein catabolism increases during fasting. (d) Little fat is incorrect because fats are not excreted in urine in this form.
Ketone bodies in urine are identified by:
A)
Rothera’s test
B)
Benzidine test
C)
Heat acetic acid test
D)
Benedict’s test
Ketone bodies in urine are detected by Rothera’s test, which identifies acetoacetic acid and acetone using sodium nitroprusside in an alkaline medium to produce a purple color. Benzidine test is used for blood detection, Heat acetic acid test is used for urinary protein, and Benedict’s test is used for reducing sugars such as glucose. Therefore, option (a) is correct.
Which of the following is a measure of variability?
A)
Mean
B)
Mode
C)
Interquartile range
D)
Percentile
A measure of variability describes how spread out the data are. The interquartile range (IQR) measures the spread of the middle 50% of the data, so it is a measure of variability. Mean and mode are measures of central tendency, while percentile indicates position in a distribution, not variability.
If a pH of a solution changes from 5 to 3, how does the hydrogen ion concentration change?
A)
Increases by a factor of 2
B)
Increases by a factor of 100
C)
Decreases by a factor of 2
D)
Decreases by a factor of 10
pH = -log10[H+]. A decrease in pH from 5 to 3 means the pH drops by 2 units. Each 1-unit decrease in pH increases hydrogen ion concentration by 10 times. Therefore, a 2-unit decrease increases [H+] by 10 × 10 = 100 times. Hence, option (b) is correct. The other options are incorrect because pH changes are logarithmic, not linear.
What is the wavelength range of the UV spectrum?
A)
100 nm to 400 nm
B)
200nm to 800 nm
C)
300 nm to 1000nm
D)
400 nm to 1600 nm
Ultraviolet (UV) radiation lies just beyond the violet end of the visible spectrum. Its commonly accepted wavelength range is about 100 nm to 400 nm. Hence option (a) is correct. Option (b) extends well into the visible region, option (c) includes visible and near-infrared regions, and option (d) mainly covers visible to infrared wavelengths.
All of the following biochemical parameters are indices of liver function test, EXCEPT :
A)
Bilirubin
B)
Albumin
C)
SGOT
D)
Creatinine
Liver function tests commonly include bilirubin, albumin, and liver enzymes such as SGOT (AST). Bilirubin assesses bile pigment metabolism, albumin reflects the liver’s synthetic function, and SGOT indicates liver cell injury. Creatinine is primarily a marker of kidney function, not liver function. Therefore, creatinine is the exception. Options (a), (b), and (c) are all related to liver function assessment, while option (d) is not.
NaF in grey vacutainer blocks _______ enzymes in blood and is used for blood sugar estimation
A)
Enolase
B)
Lipase
C)
Amylase
D)
Glycase
Sodium fluoride (NaF) in the grey vacutainer is an antiglycolytic agent used for blood glucose estimation. It inhibits the glycolytic enzyme enolase, thereby preventing breakdown of glucose in the collected blood sample. Hence blood sugar remains stable for estimation. Lipase and amylase are digestive enzymes, and 'glycase' is not the relevant enzyme here.
The degree of unsaturation of a lipid can be measured by which value?
A)
Saponification number
B)
Iodine number
C)
Reichert-Meissl number
D)
Acetyl number
The degree of unsaturation of a lipid is measured by the iodine number (or iodine value). Unsaturated fatty acids contain double bonds, and iodine adds across these double bonds; therefore, the more iodine absorbed, the greater the unsaturation.
Why others are incorrect:
(a) Saponification number measures the amount of alkali needed to saponify fat, related to average molecular weight/chain length, not unsaturation.
(c) Reichert-Meissl number measures volatile water-soluble fatty acids in fats like butter.
(d) Acetyl number measures the number of free hydroxyl groups present in a fat or oil.
All are components of Gram negative bacteria cell wall, EXCEPT:
A)
Peptido glycan layer
B)
Lipopolysaccharide
C)
Braun’s lipoprotein
D)
Teichoic acid
Gram-negative bacterial cell walls contain a thin peptidoglycan layer, an outer membrane with lipopolysaccharide (LPS), and Braun’s lipoprotein linking the outer membrane to peptidoglycan. Teichoic acid is a characteristic component of Gram-positive bacteria, not Gram-negative bacteria. Therefore, option (d) is the exception. Options (a), (b), and (c) are all components associated with Gram-negative bacterial cell walls.
Positive Immunochromatography Test for Scrub Typhus needs to be cross checked by:
A)
PCR
B)
ELISA
C)
RT-PCR
D)
Flow cytometry
A positive immunochromatography test (rapid card test) for Scrub Typhus is usually a screening test and should be confirmed by a more reliable serological assay such as ELISA, especially IgM ELISA. ELISA is widely used for cross-checking because it has better sensitivity and specificity than rapid tests. PCR can detect Orientia tsutsugamushi early in infection, but it is not the routine cross-checking method for a positive rapid immunochromatography test in standard diagnostic practice. RT-PCR is mainly for RNA targets and is not the standard answer here. Flow cytometry is not used for routine confirmation of Scrub Typhus. Therefore, the correct answer is ELISA.
Folic acid is required for the growth of:
A)
Lactobacillus sp
B)
Enterococcus faecalis
C)
Bacillus anthracis
D)
Morganella morganii
Enterococcus faecalis (formerly Streptococcus faecalis) is a classic folic-acid-requiring organism and has been used in microbiological assays for folic acid estimation. Therefore, it requires folic acid for growth.
Why others are incorrect:
- Lactobacillus sp: many species are associated more commonly with assays of vitamins such as riboflavin or niacin; they are not the standard answer here.
- Bacillus anthracis: does not characteristically require folic acid for growth.
- Morganella morganii: not known as a folic-acid-requiring test organism.
Hence, the correct answer is Enterococcus faecalis.
Qualitative test for lipids are all of the following tests, EXCEPT:
A)
Acrolein test
B)
Emulsification test
C)
Solubility test
D)
Iodine oxide test
Common qualitative tests for lipids include the acrolein test, emulsification test, and solubility test. The acrolein test detects glycerol-containing fats by producing a pungent acrolein smell on heating. Emulsification test checks the formation of emulsion due to lipids, and solubility test uses the property that lipids are insoluble in water but soluble in organic solvents. 'Iodine oxide test' is not a standard qualitative test for lipids, so it is the exception.
Which of the following is true about the primary structure of proteins?
A)
Helical structure of the protein
B)
Subunit structure of the protein
C)
3D structure of the protein
D)
Sequence of amino acids joined by a peptide bond
The primary structure of a protein refers to the linear sequence of amino acids linked together by peptide bonds. This sequence determines how the protein will fold and function. Option (a) describes secondary structure, such as alpha-helix. Option (b) refers to quaternary structure, involving multiple subunits. Option (c) refers to tertiary structure, the overall three-dimensional folding of a single polypeptide chain.
Vector for Scrub Typhus is mainly:
A)
Cyclops
B)
Rat flea
C)
Louse
D)
Trombiculid mites
Scrub typhus is caused by Orientia tsutsugamushi and is transmitted mainly by the larval stage (chigger) of trombiculid mites, especially Leptotrombidium species. Therefore, option (d) is correct.
Why others are incorrect: Cyclops is a crustacean vector/intermediate host in some parasitic diseases, rat flea transmits plague, and louse is associated with diseases like epidemic typhus—not scrub typhus.
Proteins may be denatured irreversibly by:
A)
Adding urea
B)
Bringing to isoelectric pH
C)
Heat coagulation
D)
Mercaptoethanol
Denaturation means loss of a protein’s native three-dimensional structure. Heat can unfold proteins and, on strong heating, causes coagulation with aggregation, which is usually irreversible.
Why others are incorrect:
(a) Urea denatures proteins mainly by disrupting non-covalent interactions, but this is often reversible after removal.
(b) At the isoelectric pH, proteins have minimum solubility and may precipitate, but this is not necessarily irreversible denaturation.
(d) Mercaptoethanol reduces disulfide bonds and can unfold proteins, but this change may be reversible if the reducing agent is removed and correct conditions are restored.
Therefore, the protein may be denatured irreversibly by heat coagulation.
All the techniques listed below measure proteins, EXCEPT:
A)
Nephelometry
B)
ELISA
C)
Flame photometry
D)
Radial immunodiffusion
Nephelometry, ELISA, and radial immunodiffusion are all used for protein estimation, especially immunoglobulins or other specific proteins. Nephelometry measures light scattered by antigen-antibody complexes, ELISA detects specific proteins using enzyme-linked antibodies, and radial immunodiffusion measures protein concentration by diffusion in agar. Flame photometry, however, is used to measure metal ions such as sodium, potassium, and lithium, not proteins. Therefore, the correct answer is flame photometry.
Which of the following symptoms is associated with hypocalcemia?
A)
Muscle cramps
B)
Tingling sensation in fingers or around mouth
C)
Fatigue
D)
High blood pressure
Hypocalcemia means low calcium level in blood, which increases neuromuscular excitability. A classic symptom is paresthesia—tingling or numbness around the mouth and in the fingers. Muscle cramps can also occur in hypocalcemia, but the more characteristic symptom among the given options is tingling sensation. Fatigue is nonspecific, and high blood pressure is not a typical symptom of hypocalcemia.