← Combined Technical (NG)
Past Questions
Normal serum electrolyte level of potassium is :
A)
3.5-5 mmol/L
B)
3.5-5 nm/L
C)
136-145 mmol/L
D)
146-166 mml/L
The normal serum potassium level in adults is about 3.5-5.0 mmol/L (or mEq/L). Therefore, option (a) is correct. Option (b) is incorrect because the unit 'nm/L' is wrong. Option (c) 136-145 mmol/L is the normal range for serum sodium, not potassium. Option (d) 146-166 mml/L is also not the normal potassium range and uses an incorrect unit.
All of the following are disadvantages of Radioimmunoassay, EXCEPT :
A)
Picogram quantities of substances cannot be analysed
B)
Shelf life of reagent is short
C)
Radioisotopes require stringent laws
D)
Machines are inexpensive
Radioimmunoassay (RIA) is a highly sensitive analytical technique that can detect very small, even picogram-level, quantities of substances. So option (a) is not a true statement about RIA’s limitation as written. However, the question asks for the EXCEPT among disadvantages, and the clearly non-disadvantage option is (d).
Why (d) is correct: if machines are inexpensive, that is an advantage, not a disadvantage.
Why the others are disadvantages/related concerns:
- (b) Shelf life of reagent is short: true, because radioactive reagents decay over time.
- (c) Radioisotopes require stringent laws: true, due to radiation safety, storage, handling, and disposal regulations.
- (a) Picogram quantities of substances cannot be analysed: this is actually false for RIA, because RIA is known for detecting picogram amounts; hence it does not describe a disadvantage of RIA.
Thus, the intended answer is (d) Machines are inexpensive.
Indian ink for CSF is used for detection of:
A)
Aspergillus
B)
Cryptoccocus
C)
Dermatophytes
D)
Blastomycosis
Indian ink preparation of cerebrospinal fluid (CSF) is classically used to detect Cryptococcus, especially Cryptococcus neoformans, because its thick polysaccharide capsule appears as a clear halo against the dark background.
Why others are incorrect:
- Aspergillus: usually detected by culture, microscopy, galactomannan, or histopathology, not Indian ink CSF.
- Dermatophytes: infect skin, hair, and nails; diagnosed by KOH mount/culture, not CSF Indian ink.
- Blastomycosis: diagnosed by tissue microscopy/culture/antigen tests, not typically by Indian ink CSF.
Therefore, the correct answer is option (b).
One of the best methods to determine the number of bacteria present per ml of liquid broth/ specimen is:
A)
Pour plate method
B)
Spread plate method
C)
Liquid culture
D)
Streak plate method
The pour plate method is one of the best methods for determining the number of viable bacteria per ml of a liquid specimen because a measured volume of diluted sample is mixed with molten agar and colonies are counted after incubation. This allows estimation of colony-forming units (CFU/ml). The spread plate method also helps in counting viable cells, but only a small volume is spread on the surface, so pour plate is classically preferred in such exam questions for bacterial count per ml. Liquid culture is used for growth, not accurate counting, and streak plate is mainly used for isolation of pure colonies, not enumeration.
Fouchet’s test in urine is used to detect:
A)
Ketone bodies
B)
Urobilinogen
C)
Fructose
D)
Bilirubin
Fouchet’s test is used to detect bile pigments, especially bilirubin, in urine. In this test, bilirubin is oxidized to biliverdin, producing a green/blue-green color. Therefore, option (d) is correct. The other options are incorrect because ketone bodies are detected by Rothera’s test, urobilinogen by Ehrlich’s aldehyde reaction, and fructose by Seliwanoff’s test.
WIDAL test detects:
A)
Antigen–antibody precipitation
B)
O and H agglutinins
C)
Salmonella DNA
D)
Typhoid toxin
The Widal test is a serological agglutination test used for diagnosing enteric fever (typhoid/paratyphoid). It detects antibodies in the patient's serum against the O (somatic) and H (flagellar) antigens of Salmonella typhi. Therefore, it detects O and H agglutinins.
Why others are incorrect: (a) Widal is based on agglutination, not precipitation; (c) Salmonella DNA is detected by molecular tests like PCR, not Widal; (d) Widal does not detect any typhoid toxin.
Who is the father of modern biochemistry?
A)
Carl Neuberg
B)
Justus von liebig
C)
Felix Hoppe
D)
Strasbourg
Carl Neuberg is widely known as the father of modern biochemistry because of his pioneering work in biochemical research, especially in enzyme chemistry and metabolism. Justus von Liebig is often called the father of agricultural chemistry, not modern biochemistry. Felix Hoppe-Seyler is an important founder of biochemistry as a discipline, but the title 'father of modern biochemistry' is generally attributed to Carl Neuberg. Strasbourg is a place, not a scientist.
Southern blotting analysis is used for all, EXCEPT :
A)
Detecting the presence of mutant gene
B)
Visualising DNA profile
C)
Studying a microarray
D)
Detecting restriction fragment length polymorphism
Southern blotting is a technique used to detect specific DNA sequences in DNA fragments after gel electrophoresis and transfer to a membrane. It is used for detecting mutant genes, analysing DNA profiles, and identifying restriction fragment length polymorphism (RFLP). Microarray analysis is a different high-throughput hybridization technique performed on chips or slides, not by Southern blotting. Therefore, the exception is option (c).
Commonly used confirmatory diagnostic test for Western blot is:
A)
Hepatitis A
B)
HIV
C)
Influenza
D)
Tuberculosis
Western blot has been commonly used as a confirmatory test for HIV infection after an initial screening test such as ELISA. It detects antibodies against specific HIV proteins, making it useful for confirmation. The other options are incorrect because Western blot is not the commonly used confirmatory diagnostic test for Hepatitis A, Influenza, or Tuberculosis.
Which of the following protein was first sequenced by Frederick Sanger?
A)
Myosin
B)
Insulin
C)
Myoglobin
D)
Haemoglobin
Frederick Sanger was the first scientist to determine the complete amino acid sequence of a protein, and that protein was insulin. This landmark work showed that proteins have a definite chemical structure and earned him the Nobel Prize in Chemistry in 1958. The other options are incorrect: myosin is a muscle protein not first sequenced by Sanger, myoglobin was later structurally studied by other researchers, and haemoglobin was also not the first protein sequenced by him.
Transmission of genes from one bacterium to another neighbour bacterium is known as:
A)
Vertical gene transfer
B)
Horizontal gene transfer
C)
Mutation
D)
Transduction
Gene transfer from one bacterium to another neighbouring bacterium is called horizontal gene transfer, because the genes move between organisms of the same generation rather than from parent to offspring. Vertical gene transfer is inheritance from parent to daughter cells. Mutation is a change in genetic material, not transfer between bacteria. Transduction is only one specific type of horizontal gene transfer mediated by bacteriophages, so the broader correct answer is horizontal gene transfer.
Why should glasswares be placed on a heat-resistant surface during heating?
A)
Prevent thermal shock
B)
Speeding up the process
C)
Save energy
D)
Increase efficiency
Glassware should be placed on a heat-resistant surface during heating to prevent sudden temperature changes that can crack or shatter the glass due to thermal shock. Heat-resistant surfaces distribute heat more safely and reduce stress on the glass. Options (b), (c), and (d) are incorrect because the main purpose is safety and protection of the glassware, not speeding up the process, saving energy, or increasing efficiency.
Housefly acts as mechanical vector for transmission of all of the following infections, EXCEPT:
A)
Amoebiasis
B)
Typhoid
C)
Cholera
D)
Hepatitis B
Houseflies are mechanical vectors that carry pathogens externally on their body parts or internally in the gut and contaminate food and water. They commonly spread intestinal infections such as amoebiasis, typhoid, and cholera. Hepatitis B, however, is not transmitted mechanically by houseflies; it spreads mainly through infected blood, body fluids, sexual contact, and from mother to child. Therefore, the exception is Hepatitis B.
Sterilization of glassware is done by :
A)
Autoclave
B)
Phenolic compunds
C)
Tyndallization
D)
Hot air oven
Glassware is sterilized by dry heat, and the standard method is a hot air oven. Dry heat effectively sterilizes glass items such as Petri dishes, pipettes, test tubes, and flasks without causing rust or moisture-related problems.
Why others are incorrect:
- Autoclave: Uses moist heat under pressure; mainly for culture media, dressings, and some instruments, not the preferred standard method for glassware.
- Phenolic compounds: These are disinfectants, not a sterilization method for glassware.
- Tyndallization: A method of intermittent steaming used for certain heat-sensitive materials, not routine glassware sterilization.
Therefore, the correct answer is Hot air oven.
Which of the following measures the ability of the liver to synthesize clotting factors?
A)
AST/ALT
B)
Alkaline phosphatase
C)
Bilirubin
D)
INR
INR (International Normalized Ratio) reflects prothrombin time and is used to assess the liver’s synthetic function because the liver produces several clotting factors. When liver synthesis is impaired, INR becomes prolonged. AST/ALT indicate hepatocellular injury, alkaline phosphatase suggests cholestasis, and bilirubin reflects excretory/metabolic function rather than clotting factor synthesis.
Distilled water is a poor conductor of electricity because it lacks:
A)
Air
B)
Salts and minerals
C)
Hydrogen ions
D)
Pure H2O molecules
Electric current in water is conducted mainly by dissolved ions. Distilled water is nearly free from dissolved salts and minerals, so it has very few ions to carry electricity and is therefore a poor conductor. Option (a) is irrelevant. Option (c) is incorrect because pure water has a very small number of H+ and OH− ions due to self-ionization, but not enough for good conduction. Option (d) is incorrect because distilled water is made of pure H2O molecules; the problem is the absence of dissolved ionic impurities.
Immunofluorescence test is based on the use of:
A)
Radioactive isotopes
B)
Fluorescent-labeled antibodies
C)
Enzyme-substrate reaction
D)
Heat fixation
Immunofluorescence is a serological/immunological technique in which antibodies are tagged with fluorescent dyes (such as fluorescein). These labeled antibodies bind specifically to antigens, and the fluorescence can then be seen under a fluorescence microscope. Therefore, the test is based on fluorescent-labeled antibodies.
Why others are incorrect: Radioactive isotopes are used in radioimmunoassay, not immunofluorescence. Enzyme-substrate reaction is the basis of ELISA/immunoenzyme tests. Heat fixation is only a specimen preparation step and not the principle of the test.
Wasserman Test for Syphilis is a type of:
A)
Agglutination test
B)
Precipitation test
C)
Neutralization test
D)
Complement fixation test
The Wassermann test is a classical serological test used for detecting syphilis, and it is based on the principle of complement fixation. In this test, if antibodies against the syphilis organism are present in the patient's serum, they react with the antigen and fix the complement. Therefore, the correct answer is (d) Complement fixation test.
Why others are incorrect:
(a) Agglutination test: involves clumping of particles or cells, not the basis of the Wassermann test.
(b) Precipitation test: involves formation of an insoluble antigen-antibody complex, not used here.
(c) Neutralization test: measures the ability of antibodies to neutralize toxins or viruses, not syphilis diagnosis in the Wassermann test.
In salmonella infection, stool culture is positive in :
A)
First week of illness
B)
3 — 4 weeks
C)
6 — 8 weeks of illness
D)
8 — 10 weeks
In enteric fever (salmonella infection/typhoid), different specimens become positive at different stages. Blood culture is usually positive in the 1st week, stool culture commonly becomes positive from the 2nd week onward and is most classically associated with the 3rd–4th week, while urine culture may become positive later. Therefore, the best answer is 3—4 weeks. Option (a) is more typical for blood culture, and options (c) and (d) are too late for the usual expected stool culture positivity period.
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 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.
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.
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.
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.
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).