MCQs in Biochemistry

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BiochemistryBasic Medical Science Author Email: [email protected]

Time: 40 mins Total Marks: 50 | Pass Marks: 30

BIOCHEMISTRYPlease use a dark pencil/pen to complete the test. Read the instructions at the begining carefully. This is an Sample Test Paper for practice.

Please Note: There is a Negative Marking of (-1) for each incorrect response.

1. In fatty acid synthesis, the enzyme required for priming acetyl-ACP with malonyl-ACP for chain extension

A 3-ketoacyl-ACP reductase

B 3-ketoacyl-ACP synthase

C Acetyl CoA:ACP transacylase

D Malonyl CoA:ACP transacylase

2. An enzyme of the non-oxidative phase of the pentose phosphate pathway:

A Ribulose 5-Phosphate 3-Epimerase

B 6-phosphogluconate dehydrogenase

C Methylcrotonyl-CoA carboxylase

D Acetyl-CoA carboxylase alpha

3. Biotin deficiency is characterized by all of the following except:

A hypercholesterolemia

B glossitis

C scaly dermatitis

D dementia

4. Match the following Vitamins with their daily recommended dietary intake as supplement:

A. Thiamine A. 5 mg

B. Cobalamin (Vit.B12) B. 1.1-1.2 mg

C. Niacin C. 14-16 mg

D. Pantothenic acid (B5) D. 2.4 mg

E. Biotin E. 30 μg

5. Carotenoids without Vitamin A activity:

A γ-carotene

B β-cryptoxanthin

C zeaxanthin

D lycopene

Basic Medical Sciences - 1 -

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Biochemistry

6. The enzyme that catalyzes reductive amination of α-ketoglutarate in prokaryotes and plants

A glutamate synthase

B glutaminase

C glutamate dehydrogenase

D glutamine synthetase

7. Arrange the following substrates of the glycolytic pathway in their correct order of events/reactions: (1 5)

A. 1,3-Bisphosphoglycerate

B. Fructose 1,6-bisphosphate

C. Phosphoenolpyruvate

D. Glyceraldehyde 3-phosphate

E. Glucose 6-phosphate

8. Hyperkeratosis can occur due to

A Vemurafenib

B chronic exposure to Arsenic

C chronic exposure to Mercury

D all of the above

9. What is not true about holoenzymes?

A DNA polymerases are examples of holoenzyme

B contains cofactors weakly bound to enzymes called prosthetic groups

C cofactors in holoenzymes are mostly enzymes or proteins

D apoenzyme + coenzyme

10. Match the following enzyme with their inorganic cofactors:

A. catalase A. manganese

B. cytochrome B. magnesium

C. hexokinase C. molybdenum

D. arginase D. ferrous or ferric

E. nitrate reductase E. cupric

11. An example of oxidoreductase enzyme

A chymotrypsin

B fumarase

C lactate dehydrogenase

D aminoacyl-tRNA synthetase

12. The pyruvate dehydrogenase multienzyme complex require all of the following cofactors except:

A thiamine pyrophosphate (TPP)

B cobalt

C favin adenine dinucleotide (FAD)

D magnesium


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Biochemistry

13. The enzyme that converts glutamine to glutamate and NH4+ in liver mitochondria

A glutamine synthetase

B glutamate synthase

C glutamate dehydrogenase

D glutaminase

14. Serine is synthesized from:

A glutamate

B 3-phosphoglycerate

C α-ketoglutarate

D 3-phosphohydroxypyruvate

15. Aminoacid threonine is synthesized from

A 3-phosphoglycerate

B pyruvate

C aspartate

D glutamine

16. Which of the following substances is/are responsible for brain edema due to astrocyte swelling in hepatic encephalopathy?

A glutamine

B ammonia

C glutamate

D all of the above

17. Match the following enzymes with their correct classification subgroup:

A. phospholipase C A. Hydrolase

B. lactate dehydrogenase B. Transferases

C. phosphoglucomutase C. Oxidoreductase

D. fumarase D. Isomerase

E. UDP-glucose pyrophosphorylase E. Lyases

18. Formation of glutamine is catalyzed by


B glutaminase

C glutamate synthase

D glutamate dehydrogenase

19. Which of the following is an endogenous NMDA receptor antagonist?

A dextromethorphan

B kynurenic acid

C kainic acid

D glutamic acid

20. Which of the following enzyme is a lyase?


B histidine decarboxylase

C aspartate transcarbamylase

D Uracil-DNA glycosylase


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Biochemistry

21. Which of the following is not true about Vitamin E?

A regulation of prostaglandin synthesis

B large doses may induce Vitamin A deficiency

C protects integrity of normal cell membranes

D large doses may induce hemolysis of RBC

22. Which of the following is a xanthophyll carotenoids?

A β-carotene

B lycopene

C lutein

D β-cryptoxanthin

23. Which vitamin is necessary for metabolic oxidation of tyrosine?

A Vitamin C

B Vitamin E

C Pyridoxine

D Biotin

24. An essential amino acid

A proline

B alanine

C tryptophan

D tyrosine

25. Which of the following is a cofactor of Methylmalonyl Coenzyme A mutase (MUT)?

A methylcobalamin

B adenosylcobalamin

C cyanocobalamin

D hydroxocobalamin

26. Vitamin that is essential for formation of collagen

A Pyridoxine

B Vitamin D

C Vitamin E

D Vitamin C

27. Hormones that act through Ca2+ and phosphatidylinositol bisphosphate (PIP) system

A oxytocin

B atrial natriuretic peptide (ANP)

C glucagon

D insulin

28. Enzyme that catalyzes the synthesis of fumarate from succinate and FAD

A succinyl dehydrogenase

B α-ketoglutarate dehydrogenase

C succinyl CoA synthetase

D succinate dehydrogenase

29. Succinyl CoA is a[A]_____________ compound.

∆G° for hydrolysis of ATP is [B]__________________.


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Biochemistry

30. Which of the following substrate inhibits carnitine acytransferase I?

A acetyl CoA

B malonyl CoA

C palmitoyl CoA

D succinyl CoA

31. Pick the incorrect statements about the tricarboxylic acid cycle (TCA cycle)

A involves oxidation of acetyl CoA

B amphibolic cycle which provides carbon skeleton for gluconeogenesis, fatty acid synthesis

C require enzyme succinate dehydrogenase which is a mitochondrial matrix enzyme

D pathway for reduction and reoxidation of coenzymes

32. Formation of methylmalonyl CoA from propionyl CoA require which vitamin as a cofactor?

A Thiamine

B Pyridoxine

C Vitamin B12

D Vitamin B7

33. Schardinger enzyme is found in

A cheese

B yoghurt

C boiled milk

D raw milk

34. Which vitamin is required as a precursor in the biosynthesis of coenzyme A (CoA)?

A Panthothetic acid

B Folic acid

C Pyridoxine

D Biotin

35. Constituents of enzyme xanthine oxidase:

A riboflavin

B iron atoms

C molybdenum

D all of the above

36. Match the following cofactors with their sources:

A. Nicotinamide ring of NAD+ A. Riboflavin

B. Flavin adenine dinucleotide FAD B. Niacin

C. Coenzyme A (CoA) C. Thiamine

D. α-ketoacid dehydrogenases D. Pantothenic acid


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Biochemistry

37. Regarding α-subunits of voltage gated sodium channels (Nav) true is:

A four repeat domains with six membrane-spanning segments

B six repeat domains with four membrane-spanning segments

C pore consisting selectivity filter made of positively charges amino acids

D α-subunit Nav1.3 expressed in dorsal root ganglia is associated with pain

38. What is not true about pyruvate kinase?

A catalyzes the last reaction in glycolysis

B is more active in fasting state

C cofactor of pyruvate kinase is K+

D is the key enzyme of glycolysis in muscles

39. Which of the following enzymes require lipoic acid for its activity?

A pyruvate dehydrogenase

B indole 2,3, dioxygenase

C α-ketoacid dehydrogenase

D superoxide dismutase

40. Which of the following enzyme is an oxidase / oxidoreductase?

A glutamate decarboxylase

B tyrosinase

C 2-furoyl-CoA dehydrogenase2-furoyl-CoA dehydrogenase

D uridine monophosphate synthetase

41. The gene that codes for enzyme Uridine monophosphate synthetase is located on the

A short arm of chromosome 3 (3p13)

B short arm of chromosome 11 (3 p11)

C long arm of chromosome 11 (3q11)

D long arm of chromosome 3 (3q13)

42. Conversion of β-carotene into Vitamin A occurs chiefly in the

A brain

B kidney

C intestine

D liver

43. Pellagra is due to deficiency of

A Niacin

B Riboflavin

C Thiamine

D Biotin

44. Wild type strain of bacteria that do not require any growth factors:

A Lactobacillus

B E. coli

C Haemophilus influenzae

D Neisseria meningitidis


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Biochemistry

45. Synthesis of Porphyrin ring requires all of the following except:

A acetyl CoA

B glycine

C succinyl CoA

D δ-Aminolevulinic acid

46. Amnesic shellfish poisoning is due to neurotoxin

A β-N-methylamino-l-alanine

B okadaic acid

C domoic acid

D conotoxin

47. Which of the following is involved in growth and differentiation?

A Retinoic acid

B Retinal

C Retinol

D Retinene

48. What is not true regarding congenital erythropoietic porphyria?

A urine of patients appear red

B increased synthesis of δ-aminolevulinate

C deficiency of cosynthase

D formation of large amount of uroporphyrinogen I

49. The main storage form of vitamin K in animals:

A Vitamin K2

B Vitamin K1

C phylloquinone

D phytomenadione

50. Avidin binds to which vitamin and induces its deficiency?

A Vitamin B6

B Vitamin B1

C Vitamin B12

D Vitamin B7


MCQs in Biochemistry

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