← Combined Technical (NG)
Past Questions
Enriched medium is mainly used to:
A)
Support the growth of fastidious organisms
B)
Support the growth of all microbes
C)
Inhibit unwanted organisms
D)
Differentiate between bacteria
Enriched media are basal media supplemented with extra nutrients such as blood, serum, or egg to help grow fastidious organisms that require special nutritional factors. Therefore, option (a) is correct. Option (b) is too broad because no medium supports all microbes. Option (c) describes selective media, which inhibit unwanted organisms. Option (d) describes differential media, which help distinguish bacteria based on biochemical characteristics.
Seminiferous tubules are separated by:
A)
Sertoli cells
B)
interstitial cells
C)
Intercellular fluids
D)
NATB
Seminiferous tubules in the testes are separated by interstitial tissue, which contains interstitial (Leydig) cells. These cells lie in the spaces between the seminiferous tubules and secrete testosterone.
Why others are incorrect:
(a) Sertoli cells are present inside the seminiferous tubules and support developing sperm cells; they do not separate tubules.
(c) Intercellular fluids may be present in tissues, but the tubules are specifically separated by interstitial tissue containing Leydig cells.
(d) NATB is incorrect because option (b) is correct.
Antibodies that cross the placenta from mother to fetus is:
A)
IgG
B)
IgA
C)
IgM
D)
IgE
IgG is the only major immunoglobulin class that efficiently crosses the placenta from mother to fetus, providing passive immunity to the newborn.
Why others are incorrect:
- IgA: Mainly found in secretions like saliva, tears, and breast milk; it does not significantly cross the placenta.
- IgM: It is a large pentamer molecule, so it cannot cross the placenta.
- IgE: Involved in allergy and parasitic responses; it does not cross the placenta.
Therefore, the correct answer is IgG.
Sabroud’s dextrose agar is the most common media used in :
A)
Viral culture
B)
COVID
C)
Diagnostic mycology
D)
Sensitivity to antibodies
Sabouraud’s dextrose agar (SDA) is a standard culture medium used for the isolation and growth of fungi, especially yeasts and molds. Therefore, it is most commonly used in diagnostic mycology.
Why others are incorrect:
- (a) Viral culture: Viruses require living cells for growth, not SDA.
- (b) COVID: COVID-19 is diagnosed mainly by RT-PCR, antigen tests, or related methods, not by SDA.
- (d) Sensitivity to antibodies: Antibody sensitivity testing is unrelated to SDA fungal culture media.
Which tumor marker is mostly associated with ovarian cancer?
A)
Prostate - specific antigen (PSA)
B)
Alpha-fetoprotein ( AFP)
C)
CA 125
D)
Carcinoembryogenic antigen (CEA)
CA 125 is the tumor marker most commonly associated with ovarian cancer, especially epithelial ovarian cancer.
Why others are incorrect:
- PSA is mainly a marker for prostate cancer.
- AFP is associated with hepatocellular carcinoma and some germ cell tumors.
- CEA is commonly linked with colorectal and some other gastrointestinal cancers.
Therefore, the correct answer is CA 125.
The most common site of hospital-acquired infection is:
A)
Urinary tract
B)
Gastrointestinal tract
C)
Skin
D)
Eyes
The most common hospital-acquired (nosocomial) infection is urinary tract infection (UTI), most often associated with catheter use. Hence, option (a) is correct. Gastrointestinal infections, skin infections, and eye infections can also occur in hospitals, but they are less common than catheter-associated urinary tract infections.
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.
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.
The quickest method for separation of protein :
A)
Electrophoresis
B)
Thin layer chromatography
C)
High performance liquid chromatography
D)
Ion exchange
Proteins are most quickly separated by electrophoresis because they migrate rapidly in an electric field based on their charge and size. It is a standard fast method for protein separation and analysis. Thin layer chromatography is mainly used for small molecules, not proteins. High performance liquid chromatography is effective but generally more instrument-intensive and not the quickest standard answer in basic analytical technique MCQs. Ion exchange is a chromatographic separation method, but it is slower than electrophoresis for rapid protein separation.
Which molecule combines with Acetyl-CoA in the first step of the TCA cycle?
A)
Pyruvate
B)
Citrate
C)
Oxaloacetate
D)
Alpha-ketoglutarate
In the first step of the TCA (Krebs) cycle, Acetyl-CoA combines with oxaloacetate to form citrate in a reaction catalyzed by citrate synthase. Therefore, oxaloacetate is the molecule that combines with Acetyl-CoA. Option (b) citrate is the product, not the reactant. Pyruvate is converted to Acetyl-CoA before entering the cycle, and alpha-ketoglutarate is an intermediate formed later in the cycle.
Mobility of particles during electrophoresis is based on all of the following parameters, EXCEPT :
A)
Current and voltage
B)
Quality of supporting medium
C)
pH of buffer medium
D)
Solubility of particular protein
In electrophoresis, the mobility of particles depends mainly on the applied electric field (current/voltage), the nature and quality of the supporting medium, and the pH of the buffer because pH affects the net charge on the molecules. Solubility of a particular protein is not a standard factor determining electrophoretic mobility. Therefore, option (d) is the exception. Options (a), (b), and (c) all influence migration during electrophoresis.
The screening test for syphilis is:
A)
WIDAL
B)
Microscopy
C)
Ziehl–Neelsen
D)
VDRL
VDRL (Venereal Disease Research Laboratory test) is a standard screening test for syphilis. It is a non-treponemal serological test used to detect antibodies produced in response to Treponema pallidum infection. Widal test is used for typhoid fever, Ziehl–Neelsen staining is used to detect acid-fast bacilli such as Mycobacterium tuberculosis, and microscopy alone is not the standard screening test for syphilis.
AIDS is diagnosed when CD4+ cell count falls below:
A)
600 cells/mm³
B)
200 cells/mm³
C)
500 cells/mm³
D)
350 cells/mm³
AIDS is clinically diagnosed when the CD4+ T-lymphocyte count falls below 200 cells/mm³ (or when certain AIDS-defining illnesses are present). Therefore, option (b) is correct. The other values—600, 500, and 350 cells/mm³—may indicate varying degrees of immune suppression but do not define AIDS.
To prevent hospital acquired infection, how many movements of hand hygiene have been laid down by WHO?
A)
5
B)
7
C)
6
D)
8
WHO has laid down the '5 Moments for Hand Hygiene' to prevent hospital-acquired infections. These are: before touching a patient, before a clean/aseptic procedure, after body fluid exposure/risk, after touching a patient, and after touching patient surroundings. Therefore, the correct answer is 5. Options 7, 6, and 8 are incorrect because WHO specifically recommends five moments, not those numbers.
Drug Susceptibility Test (DST) for tubercle bacilli is done by these methods, EXCEPT:
A)
Propertion method
B)
BACTEC MGIT
C)
DNA microarray
D)
HPLC
Drug Susceptibility Testing (DST) for Mycobacterium tuberculosis is used to determine whether the bacilli are resistant or sensitive to anti-TB drugs. Common DST methods include: (a) Proportion method – a standard culture-based DST method; (b) BACTEC MGIT – a liquid culture system widely used for TB drug susceptibility testing; and (c) DNA microarray – a molecular method that can detect resistance-associated mutations. (d) HPLC (High Performance Liquid Chromatography) is not a standard DST method for tubercle bacilli; it is mainly used for chemical analysis and, in mycobacteriology, may help in species identification based on mycolic acids rather than drug susceptibility testing. Therefore, HPLC is the exception.
Which of the following is the most specific cardiomarker for myocardial damage?
A)
Apolipoprotein A-1
B)
high- sensitivity C-reactive protein ( hs-CRP)
C)
Troponin - I
D)
Lipoprotein (A)
Troponin-I is the most specific biomarker for myocardial damage because it is released from injured cardiac muscle and is highly specific to cardiac tissue. It is widely used to diagnose myocardial infarction.
Why others are incorrect:
(a) Apolipoprotein A-1 is related to HDL metabolism, not a marker of acute myocardial injury.
(b) hs-CRP is an inflammatory marker and indicates cardiovascular risk, but not specific myocardial damage.
(d) Lipoprotein (A) is a cardiovascular risk factor, not a marker of acute cardiac muscle injury.
Which of the following is an example of epimers?
A)
Glucose and ribose
B)
Glucose and galactose
C)
Galactose , mannose and glucose
D)
Glucose, ribose and mannose
Epimers are sugars that differ in configuration at only one chiral carbon atom. Glucose and galactose are epimers because they differ only at the C-4 carbon.
Why others are incorrect:
(a) Glucose and ribose differ in the number of carbon atoms, so they are not epimers.
(c) Galactose, mannose and glucose are related sugars, but galactose and mannose differ at more than one chiral carbon, so the whole set is not a single example of epimers.
(d) Glucose, ribose and mannose is incorrect because ribose is a pentose, not an epimer of glucose or mannose.
The prophage of bacteriophage behaves like a segment of the host chromosome and replicates synchronously with it. This phenomenon in lysogenic cycle is known as:
A)
Biosynthesis
B)
Lysogeny
C)
Lysogenic interconversion
D)
Maturation + Assembly
In the lysogenic cycle, the bacteriophage DNA integrates into the bacterial chromosome and becomes a prophage. The prophage then behaves like a part of the host chromosome and replicates along with it during cell division. This condition is called lysogeny.
Why others are incorrect:
(a) Biosynthesis refers to synthesis of viral components during the lytic cycle.
(c) Lysogenic interconversion refers to change in properties of the host bacterium due to presence of a prophage, not the integrated state itself.
(d) Maturation + Assembly is the stage where viral particles are put together in the lytic cycle.
Which enzyme in the pentose phosphate pathway requires thymine pyrophosphate (TPP) as a coenzyme?
A)
G6PD
B)
Transaldolase
C)
Transketolase
D)
Hexokinase
In the pentose phosphate pathway, transketolase requires thiamine pyrophosphate (TPP) as a coenzyme for transfer of a 2-carbon unit between sugars. Therefore, option (c) is correct. G6PD uses NADP+ as cofactor, transaldolase does not require TPP, and hexokinase uses ATP for phosphorylation of glucose.
In the Kirby–Bauer disc diffusion method, the zone of inhibition around an antibiotic disc indicates:
A)
Bacterial growth
B)
Resistance of the antibiotic
C)
Sensitivity of the organism to the antibiotic
D)
Quality of the culture media
In the Kirby–Bauer disc diffusion test, antibiotic discs are placed on a bacterial lawn grown on agar. If the antibiotic is effective against the organism, it prevents bacterial growth around the disc, producing a clear 'zone of inhibition.' A larger clear zone generally indicates greater sensitivity, while little or no zone suggests resistance. Therefore, the zone of inhibition indicates the sensitivity of the organism to the antibiotic. Options (a), (b), and (d) are incorrect because the clear zone shows absence of growth due to antibiotic action, not bacterial growth, antibiotic resistance, or media quality.
Bence Jones proteins are derived from:
A)
Alpha globulins
B)
Beta globulins
C)
Delta globulins
D)
Gamma globulins
Bence Jones proteins are free immunoglobulin light chains found especially in disorders like multiple myeloma. Immunoglobulins belong to the gamma globulin fraction of plasma proteins, so Bence Jones proteins are derived from gamma globulins.
Why others are incorrect:
- Alpha globulins: include proteins like alpha-1 antitrypsin and haptoglobin, not immunoglobulin light chains.
- Beta globulins: include transferrin and complement components, not Bence Jones proteins.
- Delta globulins: not the relevant plasma protein fraction here.
Therefore, the correct answer is Gamma globulins.
Which of the following is a derived SI Unit?
A)
Meter
B)
Kilogram
C)
Newton
D)
Second
The SI base units include meter (length), kilogram (mass), and second (time). A derived SI unit is formed by combining base units. Newton is the SI unit of force, and it is derived as kg·m/s². इसलिए Newton is the derived SI unit. Options (a), (b), and (d) are all base SI units.
Water bath can be used to disinfect all, EXCEPT:
A)
Bacterial vaccine
B)
Serum
C)
Body fluids
D)
Urine sample
A water bath is used for heat disinfection of certain heat-sensitive laboratory materials at controlled temperatures, such as serum, body fluids, and urine samples. These materials can be disinfected without severe damage when properly heated. Bacterial vaccines, however, contain antigenic components that can be destroyed or altered by heating in a water bath, making them unsuitable for this method. Therefore, bacterial vaccine is the exception. Options (b), (c), and (d) are materials that may be disinfected using a water bath under laboratory practice.
A low blood urea nitrogen (BUN) level could indicate which of the following?
A)
Dehydration
B)
Liver failure
C)
Pre-renal azotemia
D)
Blockage of the urinary tract
BUN (blood urea nitrogen) reflects the amount of urea produced in the liver from protein metabolism and excreted by the kidneys. A low BUN level can occur when the liver cannot adequately synthesize urea, as in liver failure.
Why others are incorrect: (a) Dehydration usually increases BUN due to reduced plasma volume, (c) pre-renal azotemia raises BUN because of reduced renal perfusion, and (d) urinary tract blockage commonly causes retention of nitrogenous wastes, leading to elevated BUN rather than low BUN.
What is the primary function of a volumetric glass?
A)
Mixing liquids
B)
Heating solution
C)
Precise volume measurement
D)
Pouring liquids
Volumetric glassware, such as volumetric flasks, pipettes, and burettes, is specially designed to measure or contain very accurate volumes of liquids. Therefore, its primary function is precise volume measurement. (a) Mixing liquids is not its main purpose, though some glassware can be used for mixing. (b) Heating solution is done using apparatus like beakers or flasks made for heating. (d) Pouring liquids is only a general use, not the primary function of volumetric glassware.