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All 100 questions with answers

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  1. 1.
    Which of the following statements is/are correct about RAST? (i) It measures IgE antibodies in the serum (ii) It is scored from 0 to 6 (iii) It is the same as the skin prick test
    Show answer and explanation
    Answer: B —
    Only (i) and (ii)
    Radioallergosorbent test (RAST) measures specific IgE antibodies in the serum and is typically scored from 0 to 6, but it is not the same as a skin prick test.
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  2. 2.
    A solution with pH 4 is _____________ times more acidic than a solution with pH 6
    Show answer and explanation
    Answer: D —
    100
    Each unit change in pH represents a tenfold change in hydrogen ion concentration. A difference of 2 pH units (6−4=26 - 4 = 2) corresponds to 102=10010^2 = 100 times.
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  3. 3.
    Which of the following drugs is not an enzyme inhibitor?
    Show answer and explanation
    Answer: C —
    siRNA
    siRNA acts via RNA interference to silence gene expression by degrading mRNA rather than inhibiting an enzyme directly.
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  4. 4.
    Identify the protein that matches with the following descriptions: (i) Fibrous protein (ii) Composed of three chains (iii) Associated with Ehlers-Danlos Syndrome
    Show answer and explanation
    Answer: A —
    Collagen
    Collagen is a fibrous protein composed of a triple helix of three chains, and its defects are associated with Ehlers-Danlos syndrome.
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  5. 5.
    Enzyme activity is measured based on the intensity of emitted light in _________ method
    Show answer and explanation
    Answer: C —
    Luminiscence
    Luminescence measures enzyme activity based on the intensity of emitted light resulting from a chemical reaction.
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  6. 6.
    Pick the group of non-polar aminoacids
    Show answer and explanation
    Answer: D —
    Alanine, Leucine, Isoleucine, Methionine
    Alanine, leucine, isoleucine, and methionine all possess non-polar (hydrophobic) side chains.
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  7. 7.
    Which of he following serves the purpose of locating the radioactive emissions in the process of autoradiography?
    Show answer and explanation
    Answer: B —
    Photographic Emulsion
    Autoradiography uses a photographic emulsion to detect and locate radioactive emissions within a specimen.
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  8. 8.
    Which organelle does not contain nucleic acid?
    Show answer and explanation
    Answer: C —
    Golgi Body
    Golgi body does not contain nucleic acids, whereas ribosomes contain rRNA, and mitochondria and chloroplasts contain their own circular DNA.
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  9. 9.
    The plasma protein that is involved in copper homeostasis is ________
    Show answer and explanation
    Answer: A —
    Ceruloplasmin
    Ceruloplasmin is the major copper-carrying protein in the blood and plays a key role in copper homeostasis.
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  10. 10.
    Which technique/s can be used for the analysis of nucleic acids? (i) PAGE (ii) Northern Blotting (iii) SDS PAGE (iv) Southern Blotting
    Show answer and explanation
    Answer: D —
    Only (i), (ii) and (iv)
    PAGE, Northern blotting, and Southern blotting are used for nucleic acid analysis, whereas SDS-PAGE is primarily used for proteins.
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  11. 11.
    Identify the class of antibody with the bighest avidity for antigens:
    Show answer and explanation
    Answer: B —
    IgM
    Due to its pentameric structure containing 10 antigen-binding sites, IgM exhibits the highest avidity for antigens.
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  12. 12.
    A buffer solution contain 0.36 M sodium acetate (CH3COONa) and 0.036 M acetic acid (CH3COOH),pKa=4.8. What is the pH of this buffer solution?
    Show answer and explanation
    Answer: C —
    5.8
    Using Henderson-Hasselbalch equation: pH=pKa+log⁡([A−][HA])=4.8+log⁡(0.360.036)=4.8+log⁡(10)=4.8+1=5.8\text{pH} = \text{p}K_a + \log\left(\frac{[A^-]}{[HA]}\right) = 4.8 + \log\left(\frac{0.36}{0.036}\right) = 4.8 + \log(10) = 4.8 + 1 = 5.8.
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  13. 13.
    Which kind of shift is associated with uv absorption of DNA that is denatured?
    Show answer and explanation
    Answer: C —
    Hyperchromic shift
    Denaturation of DNA exposes the bases, leading to an increase in UV absorbance, known as a hyperchromic effect or hyperchromic shift.
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  14. 14.
    Match the following correctly: (i) Oxidoreductase (a) Fumarase (ii) Hydrolase (b) Aminoacyl tRNA Synthase (iii) Lyase (c) Urease (iv) Ligase (d) Catalase
    Show answer and explanation
    Answer: B —
    (i)-(d), (ii)-(c), (iii)-(a), (iv)-(b)
    Catalase is an oxidoreductase, Urease is a hydrolase, Fumarase is a lyase, and Aminoacyl tRNA synthase is a ligase.
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  15. 15.
    The aminoacid that cannot be found in alpha-helix structure of proteins is _________
    Show answer and explanation
    Answer: A —
    Proline
    Proline's rigid cyclic structure lacks the necessary amide hydrogen for hydrogen bonding and introduces a kink, making it an alpha-helix breaker.
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  16. 16.
    Which term represents the number of substrate molecules that can be converted to product by a single enzyme molecule per unit time?
    Show answer and explanation
    Answer: D —
    T urnover number
    Turnover number (kcatk_{cat}) is the maximum number of substrate molecules converted to product per enzyme molecule per unit time.
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  17. 17.
    Which of the following is used to bombard the sample in Mass spectrometry?
    Show answer and explanation
    Answer: C —
    Electrons
    In standard electron ionization mass spectrometry, a beam of high-energy electrons is used to bombard and ionize the sample molecules.
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  18. 18.
    The proteins bound to ion exchange resins can be displaced by altering the ____________
    Show answer and explanation
    Answer: B —
    Ionic strength of eluent buffer
    Elution in ion-exchange chromatography is typically achieved by altering the ionic strength or pH of the eluent buffer to compete with the bound proteins.
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  19. 19.
    Pick the incorrect statement
    Show answer and explanation
    Answer: D —
    NADH dehydrogenase is an extrinsic protein
    NADH dehydrogenase (Complex I) is a multi-subunit integral membrane protein complex, not an extrinsic/peripheral protein.
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  20. 20.
    Which of the following diseases is associated with an elevated value of serum Creatine kinase-3 (CK3)?
    Show answer and explanation
    Answer: D —
    Muscular Dystrophy
    CK-3 (CK-MM) is the muscle-specific isoenzyme of creatine kinase, and its levels are markedly elevated in muscular dystrophies and myocardial infarction.
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  21. 21.
    Serum free fatty acids are found in combination with _________
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    Answer: C —
    Albumin
    Free fatty acids in circulation are transported non-covalently bound to serum albumin.
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  22. 22.
    All N-linked oligosaccharides have _______
    Show answer and explanation
    Answer: A —
    Pentasaccharide core
    All N-linked glycoproteins share a common pentasaccharide core consisting of three mannoses and two N-acetylglucosamines.
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  23. 23.
    Hemoglobin containing two mutant β-globin chain (Hbsβ) moves slowly towards anode during electrophoresis is due to the presence of ____________
    Show answer and explanation
    Answer: C —
    Valine
    In sickle cell hemoglobin (HbS), glutamate is replaced by valine at position 6, removing a negative charge and altering electrophoretic mobility.
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  24. 24.
    All the monosaccharides contain one or more chiral carbon atoms except
    Show answer and explanation
    Answer: A —
    Dihydroxyacetone
    Dihydroxyacetone is a ketotriose and lacks an asymmetric (chiral) carbon atom.
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  25. 25.
    Lipids have ____ specific gravities than water
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    Answer: B —
    Less
    Lipids have a specific gravity less than 1.0, which allows them to float on water.
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  26. 26.
    Chemical name of Guanine is
    Show answer and explanation
    Answer: A —
    2-amino, 6-oxypurine
    Guanine is chemically known as 2-amino-6-oxypurine (or 2-amino-1,9-dihydro-6H-purin-6-one).
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  27. 27.
    Number of base pairs per one complete turn of DNA double helix are:
    Show answer and explanation
    Answer: B —
    10
    Standard B-form DNA contains approximately 10 (specifically 10.4) base pairs per complete helical turn.
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  28. 28.
    A drug _____ inhibits protein synthesis in both prokaryotes and eukaryotes
    Show answer and explanation
    Answer: C —
    Puromycin
    Puromycin acts as an aminoacyl-tRNA analog, causing premature chain termination in both prokaryotic and eukaryotic protein synthesis.
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  29. 29.
    Prokaryotic transcription start regions are called as
    Show answer and explanation
    Answer: C —
    Promoters
    Promoters are DNA sequences located near the transcription start sites that bind RNA polymerase to initiate transcription.
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  30. 30.
    Pribnow-Schaller box has a sequence of _________
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    Answer: A —
    TATAAT
    The Pribnow box is a conserved sequence (TATAAT) found about 10 bases upstream of the transcription start site in prokaryotes.
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  31. 31.
    The Hypothesis is used to make _____
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    Answer: B —
    Predictions
    A scientific hypothesis is formulated to generate testable predictions.
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  32. 32.
    Non-probability is also known as ________
    Show answer and explanation
    Answer: D —
    Deliberate sampling
    Non-probability sampling is also referred to as purposive or deliberate sampling.
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  33. 33.
    Precision is the closeness of a ________
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    Answer: A —
    repeated measurements
    Precision refers to the degree of reproducibility or closeness among repeated measurements.
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  34. 34.
    The expression of probability density function whose values range from zero to positive infinity is _______
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    Answer: A —
    Chi-square distribution
    The Chi-square distribution is a continuous probability distribution defined for positive real numbers ranging from zero to infinity.
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  35. 35.
    χ2\chi^2 with n-1 degrees of freedom equivalent to __________
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    Answer: A —
    (n−1)s2σ2\frac{(n-1)s^2}{\sigma^2}
    The chi-square statistic for variance is calculated as χ2=(n−1)s2σ2\chi^2 = \frac{(n-1)s^2}{\sigma^2}.
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  36. 36.
    Coefficient of variation is the measure of ratio of _____ stated as a percentage
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    Answer: D —
    standard deviation to the mean
    Coefficient of variation (CV) is defined as the ratio of the standard deviation to the mean, expressed as a percentage.
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  37. 37.
    The term "biological reference interval" that deemed normal for a healthy person approved by _________
    Show answer and explanation
    Answer: B —
    ISO 15189
    ISO 15189 specifies requirements for quality and competence in medical laboratories, including biological reference intervals.
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  38. 38.
    Reference value of serum creatinine in adult male would be ____________
    Show answer and explanation
    Answer: A —
    0.9-1.2 mg/dL
    Question Cancelled by KPSC.
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  39. 39.
    F test result is obtained by calculating the _____
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    Answer: D —
    Between treatment mean square divided by residual mean square
    The F-statistic in ANOVA is the ratio of the between-treatment mean square to the residual (within-treatment) mean square.
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  40. 40.
    The nonparametric method used to compare a single sample with some hypothesized value is ______________
    Show answer and explanation
    Answer: D —
    A sign test
    The sign test is a non-parametric statistical test used to test hypotheses about the median of a single sample.
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  41. 41.
    Which of the following statements regarding Basal Metabolic Rate is incorrect?
    Show answer and explanation
    Answer: C —
    It is the minimum amount of energy required to sustain vital functions during sleep
    BMR is measured under awake, resting conditions, not strictly during sleep (sleeping metabolic rate can be slightly lower than BMR).
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  42. 42.
    Which of the following is an appetite suppressant?
    Show answer and explanation
    Answer: B —
    Serotonin
    Serotonin acts as an anorexigenic (appetite suppressant) neurotransmitter in the central nervous system.
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  43. 43.
    Select the false statement regarding Carcino Embryonic Antigen
    Show answer and explanation
    Answer: B —
    Useful for diagnosing localized breast cancer
    CEA is not useful or sensitive enough for the screening or diagnosis of early or localized breast cancer.
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  44. 44.
    Which of the following is an oncosuppresser gene?
    Show answer and explanation
    Answer: D —
    p21
    p21 is a cyclin-dependent kinase inhibitor that functions as a tumor suppressor (oncosuppressor) gene product.
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  45. 45.
    Which of the following vitamin do not have specific role in bone formation?
    Show answer and explanation
    Answer: A —
    Pyridoxal phosphate
    Pyridoxal phosphate (Vitamin B6) is primarily a coenzyme in amino acid metabolism and does not have a direct specific role in bone formation like Vitamins D, K, and C.
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  46. 46.
    All the following are anti-vitamins except
    Show answer and explanation
    Answer: B —
    T yramine
    Tyramine is a naturally occurring trace amine, whereas avidin, citral, and linetin function as anti-vitamins.
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  47. 47.
    The toxin responsible for Epidemic dropsy is
    Show answer and explanation
    Answer: D —
    Sanguinarine
    Epidemic dropsy is caused by the ingestion of mustard oil contaminated with sanguinarine, a toxic alkaloid from Argemone mexicana.
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  48. 48.
    Which mineral deficiency is characterized by both hematological and neurological manifestations?
    Show answer and explanation
    Answer: B —
    Copper
    Copper deficiency causes anemia (hematological) as well as myelopathy and neuropathy (neurological manifestations resembling B12 deficiency).
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  49. 49.
    T etany is seen in
    Show answer and explanation
    Answer: C —
    Metabolic alkalosis
    Metabolic alkalosis decreases ionized calcium levels by increasing calcium binding to albumin, leading to neuromuscular irritability and tetany.
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  50. 50.
    Which of the following enzyme do NOT require biotin for its action?
    Show answer and explanation
    Answer: A —
    Aminoimidazole ribonucleotide carboxylase
    Aminoimidazole ribonucleotide (AIR) carboxylase is involved in purine biosynthesis and does not require biotin, unlike the other listed carboxylases.
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  51. 51.
    Select the technique that is used for studying gene expression in a tissue
    Show answer and explanation
    Answer: C —
    Microarray technique
    DNA microarrays are widely used to measure the expression levels of large numbers of genes simultaneously across tissues.
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  52. 52.
    Which of the following statement is false regarding innate immunity?
    Show answer and explanation
    Answer: B —
    Lymphocytes play a major role
    Lymphocytes (T and B cells) are the primary mediators of adaptive immunity, not innate immunity.
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  53. 53.
    The autoimmune disease where tissue destruction is mediated directly by T cells is
    Show answer and explanation
    Answer: A —
    Rheumatoid arthritis
    Question Cancelled by KPSC.
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  54. 54.
    Maternal serum Alpha feto protein level is decreased in
    Show answer and explanation
    Answer: B —
    Down syndrome
    Maternal serum alpha-fetoprotein (MSAFP) levels are decreased in Down syndrome and increased in neural tube defects like anencephaly.
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  55. 55.
    Which of the following is an RNA directed site specific nuclease?
    Show answer and explanation
    Answer: A —
    CRISPER-Cas9
    CRISPR-Cas9 uses a guide RNA molecule to direct the Cas9 endonuclease to specific target DNA sequences.
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  56. 56.
    Which of the following is a sulfur containing vitamin?
    Show answer and explanation
    Answer: A —
    Thiamine
    Thiamine (Vitamin B1) contains both a thiazole ring and a sulfur atom.
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  57. 57.
    All the following features are true regarding kwashiorkor EXCEPT
    Show answer and explanation
    Answer: A —
    Age of onset is 1-5 years
    Question Cancelled by KPSC.
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  58. 58.
    Which of the following vector carries the risk of insertional mutagenesis when used in gene therapy?
    Show answer and explanation
    Answer: A —
    Retroviruses
    Retroviruses integrate their genetic material into the host genome, posing a risk of insertional mutagenesis.
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  59. 59.
    Simultaneous analysis of multiple metabolites in the same blood spot is referred to as
    Show answer and explanation
    Answer: A —
    Second-Tier testing
    Question Cancelled by KPSC.
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  60. 60.
    The test that is done to assess vitamin B12 absorption is
    Show answer and explanation
    Answer: C —
    Schilling test
    The Schilling test was historically designed to measure absorption of Vitamin B12 and diagnose pernicious anemia.
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  61. 61.
    Aspirin is used in the treatment of myocardial infarction since it inhibits platelet aggregation by inhibiting the synthesis of
    Show answer and explanation
    Answer: B —
    Thromboxane
    Low-dose aspirin irreversibly inhibits platelet cyclooxygenase (COX-1), thereby blocking the synthesis of pro-aggregatory thromboxane A2.
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  62. 62.
    Refsum disease characterized by vision loss, anosmia ataxia and polyneuropathy is due to defect in
    Show answer and explanation
    Answer: A —
    Fatty acid oxidation
    Refsum disease is caused by a defect in the alpha-oxidation of branched-chain fatty acids (phytanic acid).
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  63. 63.
    The assay of 5 Hydroxy indole acetic acid in urine is useful in the diagnosis of
    Show answer and explanation
    Answer: C —
    Carcinoid syndrome
    5-Hydroxyindoleacetic acid (5-HIAA) is the main metabolite of serotonin and its elevated urinary excretion diagnoses carcinoid tumors.
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  64. 64.
    Pellagra like symptoms is commonly seen in disorders associated with the defect in the metabolism of
    Show answer and explanation
    Answer: D —
    Tryptophan
    Tryptophan is a dietary precursor for niacin (Vitamin B3); disorders of its metabolism (like Hartnup disease) present with pellagra-like symptoms.
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  65. 65.
    The rate limiting enzymes of gluconeogenesis are\n(i) Pyruvate carboxylase\n(ii) Pyruvate dehydrogenase\n(iii) Glucose-6-phosphatase\n(iv) Phosphofructokinase
    Show answer and explanation
    Answer: C —
    (i) and (iii)
    Key bypass and rate-limiting enzymes of gluconeogenesis include pyruvate carboxylase and glucose-6-phosphatase.
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  66. 66.
    The type of porphyria associated with the defect in the enzyme uroporphyrinogen decarboxylase is
    Show answer and explanation
    Answer: A —
    Porphyria cutanea tarda
    Porphyria cutanea tarda (PCT) is caused by a deficiency in uroporphyrinogen decarboxylase.
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  67. 67.
    Ochronosis, a condition where black pigments are deposited in cartilage is due to deficiency of the enzyme
    Show answer and explanation
    Answer: B —
    Homogentisic acid oxidase
    Alkaptonuria results from homogentisic acid oxidase deficiency, leading to accumulation of homogentisic acid and ochronotic pigmentation.
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  68. 68.
    All of the following are types of type II detoxification reactions except
    Show answer and explanation
    Answer: A —
    Oxidation
    Oxidation is a Phase I (Type I) xenobiotic metabolism reaction, whereas conjugation, acetylation, and sulfation are Phase II (Type II) reactions.
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  69. 69.
    Which of the following is not a diagnostic-criteria for a metabolic syndrome?
    Show answer and explanation
    Answer: C —
    HDL-cholesterol - more than 50 mg/dl
    Reduced HDL-cholesterol (< 40 mg/dL in men, < 50 mg/dL in women) is a criterion, not HDL greater than 50 mg/dL.
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  70. 70.
    The liver function test parameters for a patient admitted with jaundice is as follows serum total bilirubin - 10 mg/dl, Direct bilirubin - 9.5 mg/dl. Urine: Bile salts and bile pigments - positive which of the following enzymes is increased in this patient?
    Show answer and explanation
    Answer: B —
    Alkaline phosphatase
    The clinical picture of conjugated hyperbilirubinemia with positive bile salts/pigments points to obstructive jaundice, which characteristically elevates alkaline phosphatase.
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  71. 71.
    Urea reduction ration is used to
    Show answer and explanation
    Answer: A —
    Assess the adequacy of hemodialysis
    Urea reduction ratio (URR) is a mathematical expression used to measure the adequacy of hemodialysis treatment.
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  72. 72.
    The lab data of a patient's serum sample were as follows: T otal Cholesterol: 300 mg/dL, HDL cholesterol: 40 mg/dl and Triglycerides : 200 mg/dL The calculated LDL cholesterol level for the patient is
    Show answer and explanation
    Answer: C —
    220 mg/dL
    Using Friedewald formula: LDL=Total−HDL−(Triglycerides/5)=300−40−(200/5)=300−40−40=220 mg/dLLDL = Total - HDL - (Triglycerides / 5) = 300 - 40 - (200 / 5) = 300 - 40 - 40 = 220 \text{ mg/dL}.
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  73. 73.
    All of the following enzymes are involved in substrate level phosphorylation except
    Show answer and explanation
    Answer: D —
    Phosphoenolpyruvate carboxykinase
    Phosphoenolpyruvate carboxykinase (PEPCK) catalyzes the decarboxylation of oxaloacetate to PEP utilizing GTP without net substrate-level phosphorylation of ADP.
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  74. 74.
    Regan isoenzymes is increased in
    Show answer and explanation
    Answer: A —
    Carcinoma of lung
    The Regan isoenzyme is a placental alkaline phosphatase variant often ectopically expressed in lung cancers and other malignancies.
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  75. 75.
    Ezetimibe reduces blood cholesterol levels by
    Show answer and explanation
    Answer: B —
    Inhibiting absorption
    Ezetimibe selectively inhibits intestinal absorption of cholesterol and phytosterols at the brush border of the small intestine.
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  76. 76.
    Fatty liver can be prevented by
    Show answer and explanation
    Answer: A —
    Methionine
    Methionine acts as a lipotropic factor (via its conversion to SAM and involvement in phosphatidylcholine synthesis) to prevent hepatic lipid accumulation.
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  77. 77.
    Which of the following statement in NOT TRUE about Levey-Jennings chart?
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    Answer: A —
    QC sample should be analyzed for 20 days
    Question Cancelled by KPSC.
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  78. 78.
    All of the following are types of preanalyltical variables except
    Show answer and explanation
    Answer: D —
    Water quality
    Water quality is an analytical/laboratory environmental variable, whereas patient identification, collection, and transcription errors are preanalytical.
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  79. 79.
    Triple test, commonly used in maternal screening in second trimester include all of the following markers except
    Show answer and explanation
    Answer: C —
    Progesterone
    The traditional triple test includes AFP, hCG, and unconjugated estriol; progesterone is not part of this panel.
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  80. 80.
    Flipped pattern of Lactate dehydrogenase isoenzyme is seen in
    Show answer and explanation
    Answer: A —
    Myocardial infarction
    In myocardial infarction, serum LDH-1 exceeds LDH-2 (flipped pattern), unlike the normal pattern where LDH-2 > LDH-1.
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  81. 81.
    For Covid 19 RT-PCR test mineral used in RTPCR process
    Show answer and explanation
    Answer: B —
    Mg
    Magnesium (Mg2+Mg^{2+}) ions serve as an essential cofactor for Taq DNA polymerase in RT-PCR assays.
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  82. 82.
    The VLDL, LD: levels increase in blood due to high intake of
    Show answer and explanation
    Answer: B —
    Fructose diet
    High dietary fructose bypasses phosphofructokinase regulation and stimulates hepatic de novo lipogenesis, raising VLDL and lipid levels.
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  83. 83.
    The elementary composition of the human body (dry weight basis) in %
    Show answer and explanation
    Answer: A —
    C 50%, O 20%, H 10%, N 8.5%
    Question Cancelled by KPSC.
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  84. 84.
    Normal chemical composition for a man weighting 65 kg
    Show answer and explanation
    Answer: D —
    None
    None of the standard compositional breakdown options match typical reference man values accurately.
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  85. 85.
    A 54-year male presents with acute abdominal pain, no skin photosensitization, large amount of aminolevulinic acid (ALA) and porphobilinogen (PBG) in urine, and symptoms exacerbated by steroids and several other drugs. Which of the following best describes the conditions?
    Show answer and explanation
    Answer: B —
    Acute intermittent porphyria
    The clinical presentation of acute abdominal attacks, elevated urinary ALA and PBG, and precipitation by drugs is characteristic of acute intermittent porphyria.
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  86. 86.
    A 10-year old boy develops sever diarrhoea while travelling to India. the laboratory blood investigation shows arterial blood pH 7.25; partial pressure of carbon dioxide 24 mm Hg; bicarbinate 10 mEq/L and normal anion gap. Which of the following is correct diagnosis?
    Show answer and explanation
    Answer: A —
    Metabolic acidosis
    Low pH, low bicarbonate, and normal anion gap secondary to severe diarrhea indicate normal anion gap metabolic acidosis (due to bicarbonate loss).
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  87. 87.
    A 40-year old woman presented with history of fatigue, easy bruising, bleeding from gums while brushing her teeth and a diffuse rash involving her extremities and trunk that had been present for several days. The deficiency of which of the following is because of her symptoms?
    Show answer and explanation
    Answer: D —
    Ascorbic acid
    Bleeding gums, petechiae, and bruising are classic signs of scurvy, caused by ascorbic acid (Vitamin C) deficiency.
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  88. 88.
    A 29-year old man comes to his doctor with symptoms of HIV infection. The doctor orders several confirmatory tests, for one of them a protein sample is taken and is run on electrophoretic gel, causing it to separate by size and charge. The protein was then transferred to a membrane, and labelled antibody is added to allow visualization of this protein. Which of the following tests in described here?
    Show answer and explanation
    Answer: B —
    Western blot
    The Western blot technique is used to detect specific proteins transferred to a membrane using labeled antibodies.
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  89. 89.
    In cancer patients who have been continuously receiving methotrexate, the target cells of tumor with time become sensitive to his drug. In this case, most commonly gene amplification of the following enzyme is observed:
    Show answer and explanation
    Answer: A —
    Dihydrofolate reductase
    Resistance to methotrexate frequently develops via gene amplification of dihydrofolate reductase (DHFR), its primary target enzyme.
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  90. 90.
    A doctor administered allopurinol to a 26-year old young man with symptoms of gout. Which of the following pharmacological action of allopurinol ensures therapeutic effect?
    Show answer and explanation
    Answer: A —
    Inhibiting uric acid synthesis
    Allopurinol is a xanthine oxidase inhibitor, which blocks the synthesis of uric acid from hypoxanthine and xanthine.
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  91. 91.
    A 56-year old man was operated on prostate cancer, three months later he underwent a course of radiotherapy and chemotherapy. .The complex of medicinal preparations prescribed to the patient included 5-fluoro-deoxyuridine, which is a thymidylate synthase inhibitor, Which of the following biomolecule's synthesis is blocked by the drug?
    Show answer and explanation
    Answer: A —
    DNA
    By inhibiting thymidylate synthase, 5-fluoro-deoxyuridine prevents dTMP formation, thereby blocking DNA replication and synthesis.
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  92. 92.
    A patient with radiation therapy because of brain tumor was prescribed vitamin E and a micro element with antioxidant function. Which of the following can be used for this purpose?
    Show answer and explanation
    Answer: B —
    Selenium
    Selenium is an essential trace element acting as an antioxidant cofactor for glutathione peroxidase.
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  93. 93.
    A 3-year old child comes to the hospital with history of biting his lips and fingers, involuntary movements of upper limb and mental retardation. he has a younger healthy sister. Lab investigations showed high serum uric acid. Which of the following is the most likely diagnosis?
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    Answer: B —
    LeschNyhah Syndrome
    Self-mutilation, neurological impairment, and hyperuricemia are hallmark features of Lesch-Nyhan syndrome (HGPRT deficiency).
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  94. 94.
    A 7-year boy comes to the hospital with yellow discoloration of eyes, decreased apetite and general malaise for last 1 week. She has been passing dark colored urine and high colored faces for the same duration. Lab investigations showed serum total bilirubin 4.5 mg%, direct bilirubin 1.2 mg%, indirect faeces 3.3 mg%. liver enzymes are normal. Which of the following is the most likely cause of jaundiced in this patient?
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    Answer: A —
    Obtrusive jaundice
    Question Cancelled by KPSC.
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  95. 95.
    A 20-year old male visits dermatology OPD with complaints of increased sensitivity to sunlight causing blistering and crusting of skin only few minutes of sun exposure. Delayed growth and intellectual disability were noticed. Skin biopsy was taken. Which of the following is the most likely diagnosis?
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    Answer: A —
    Xeroderma pigmentosum
    Extreme photosensitivity, blistering, and associated neurological or developmental abnormalities point to Xeroderma pigmentosum (defect in DNA repair).
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  96. 96.
    a 20-year old male patient presented with severe abdominal pain with difficulty in fine motor tasks. Lab investigation showed elevated liver enzymes and increased urinary calcium and phosphate Opthalamological examination revealed Kayser Fleischer ring in the cornea. Which of the following is most likely cause of the presenting symptoms in this case?
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    Answer: B —
    Copper excess
    Kayser-Fleischer rings and hepatic/neurological symptoms are characteristic of Wilson's disease, caused by copper accumulation (excess).
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  97. 97.
    A patient is undergoing radiation therapy because of breast cancer. This resulted in increased lipid peroxidation processes. In the course of which active forms of oxygen including superoxide anion radical are formed in the human body. Which of the following enzymes inactivates this anion?
    Show answer and explanation
    Answer: A —
    Superoxide dismutase
    Superoxide dismutase (SOD) specifically catalyzes the dismutation of superoxide radicals into molecular oxygen and hydrogen peroxide.
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  98. 98.
    The Anfinsen's dogma states that
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    Answer: B —
    Primary structure directs in vivo folding
    Anfinsen's dogma states that the native three-dimensional conformation of a protein is determined entirely by its amino acid primary sequence.
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  99. 99.
    The maximum buffering capacity occurs at
    Show answer and explanation
    Answer: A —
    ±1 pH unit on either side of pKa
    A buffer is most effective and has maximum buffering capacity within ±1\pm 1 pH unit of its pKa (pH=pKa±1pH = pKa \pm 1).
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  100. 100.
    The defective DNA base excision repair (BER) is found in
    Show answer and explanation
    Answer: C —
    Mutyh-associated polyposis (MAP)
    MUTYH-associated polyposis (MAP) is caused by biallelic mutations in the MUTYH gene, which is a key component of the base excision repair pathway.
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