Name: I.D.

1

Port-said University

Faculty: Science Date: 27 /2/2013

Department: Chemistry Time: 2 hrs.

Class Year: Diploma of Biochemistry Full mark: 120 marks

Final Exam “Metabolism”

(I) Choose the correct answer: (90 Marks)

1. Lactate formed in muscles can be utilized through (A) Rapoport-Luebeling cycle

(B) Glucose-alanine cycle

(C) Cori’s cycle

(D) Citric acid cycle

2. Glucose uptake by liver cells is (A) Energy-consuming (B) A saturable process

(C) Insulin-dependent (D) Insulin-independent

3. During starvation, ketone bodies are used as a fuel by (A) Erythrocytes (B) Brain

(C) Liver (D) All of these

4. The intermediate in hexose monophosphate shunt is (A) D-Ribolose (B) D-Arobinose

(C) D-xylose (D) D-lyxose

5. Glycogen synthetase activity is depressed by (A) Glucose (B) Insulin

(C) Cyclic AMP (D) Fructokinase

6. Dihydroxyacetone phosphate and glyceraldehyde-3-phosphate are interconverted by (A) Triose isomerase

(B) Phosphotriose isomerase

(C) Diphosphotriose isomerase

(D) Dihydroxyacetone phosphorylase

7. Under anaerobic conditions the glycolysis one mole of glucose yields __ moles of ATP. (A) One (B) Two (C) Eight (D) Thirty

8. The conversion of alanine to glucose is termed (A) Glycolysis (B) Oxidative decarboxylation

(C) Specific dynamic action (D) Gluconeogenesis

9. The following is an enzyme required for glycolysis: (A) Pyruvate kinase (B) Pyruvate carboxylase

(C) Glucose-6-phosphatose (D) Glycerokinase

10. The number of molecules of ATP produced by the total oxidation of acetyl CoA in TCA cycle is (A) 6 (B) 8 (C) 10 (D) 12

11. Fatty acids cannot be converted into carbohydrates in the body as the following reaction is not possible. (A) Conversion of glucose-6-phosphate into glucose

(B) Fructose 1, 6-bisphosphate to fructose-6- phosphate

(C) Transformation of acetyl CoA to pyruvate

(D) Formation of acetyl CoA from fatty acids

12. Pepsin acts on denatured proteins to produce (A) Proteoses and peptones (B) Polypeptides

(C) Peptides (D) Dipeptides

13. The enzyme trypsin is specific for peptide bonds of (A) Basic amino acids

(B) Acidic amino acids

(C) Aromatic amino acids

(D) Next to small amino acid residues

14. The main sites for oxidative deamination are (A) Liver and kidney

(B) Skin and pancreas

(C) Intestine and mammary gland

(D) Lung and spleen

15. Transfer of the carbamoyl moiety of carbamoyl phosphate to ornithine is catalyzed by a liver mitochondrial enzyme: (A) Carbamoyl phosphate synthetase

(B) Ornithine transcarbamoylase

(C) N-acetyl glutamate synthetase

(D) N-acetyl glutamate hydrolase 16. The number of ATP required for urea synthesis is (A) 0 (B) 1 (C) 2 (D) 3

17. The 2 nitrogen atoms in urea are contributed by (A) Ammonia and glutamate (B) Glutamine and glutamate

(C) Ammonia and aspartate (D) Ammonia and alanine 18. All of the following are required for synthesis of glutamine except (A) Glutamate (B) Ammonia

(C) Pyridoxal phosphate (D) ATP

19. After digestion amino acids (A) Are absorbed into portal circulation

(B) Are absorbed into lymph

(C) Are excreted to the extent of 50%

(D) Converted into glucose in the intestine 20. NH3 is detoxified in brain chiefly as (A) Urea (B) Uric acid

(C) Creatinine (D) Glutamine

21. A compound serving a link between citric acid cycle and urea cycle is (A) Malate (B) Citrate

(C) Succinate (D) Fumarate

22. Mechanism by which NH3 is removed from the kidney is (A) Urea formation (B) Uric acid formation

(C) Creatinine formation (D) None of these

2

23. Free fatty acids are transported in the blood (A) Combined with albumin

(B) Combined with fatty acid binding protein

(C) Combined with β- lipoprotein

(D) In unbound free salts

24. β-Oxidation of fatty acids requires all the following coenzymes except (A) CoA (B) FAD (C) NAD (D) NADP

25. Propionyl CoA is formed on oxidation of (A) Monounsaturated fatty acids

(B) Polyunsaturated fatty acids

(C) Fatty acids with odd number of carbon atoms

(D) None of these 26. Ketone bodies are synthesized in (A) Adipose tissue (B) Liver

(C) Muscles (D) Brain

27. All the following statements about carnitine are true except (A) It can be synthesized in the human body

(B) It can be synthesized from methionine and lysine

(C) It is required for transport of short chain fatty acids into

mitochondria

(D) Its deficiency can occur due to haemodialysis

28. All the following can be oxidized by βoxidation except (A) Palmitic acid (B) Phytanic acid

(C) Linoleic acid

(D) Fatty acids having an odd number of carbon atoms 29. Glycerol released from adipose tissue by hydrolysis of triglycerides is mainly (A) Taken up by liver

(B) Taken up by extra-hepatic tissues

(C) Reutilized in adipose tissue

(D) Excreted from the body

30. Net ATP generation on complete oxidation of stearic acid is (A) 129 (B) 131 (C) 146 (D) 148

31. Net generation of energy on complete oxidation of a 17-carbon fatty acid is (A) Equal to the energy generation from a 16-carbon fatty acid

(B) Equal to the energy generation from an 18-carbon fatty acid

(C) Less than the energy generation from a 16-carbon fatty acid

acid and an 18-carbon fatty acid

32. Net energy generation on complete oxidation of linoleic acid is (A) 148 ATP equivalents (B) 146 ATP equivalents

(C) 144 ATP equivalents (D) 142 ATP equivalents

33. The fatty acids containing even number and odd number of carbon atoms as well as the unsaturated fatty acids are oxidized by (A) α-oxidation (B) β-oxidation

(C) ω-oxidation (D) All of these

34. The absorption of glucose in the digestive tract (A) Occurs in the small intestine

(B) Is stimulated by the hormone Glucagon

(C) Occurs more rapidly than the absorption of any other sugar

(D) Is impaired in cases of diabetes mellitus

35. The enzymes involved in Phosphorylation of glucose to glucose 6- phosphate are (A) Hexokinase (B) Glucokinase

(C) Phosphofructokinase (D) Both (A) and (B)

36. Which of the following statements regarding T.C.A cycle is true? (A) It is an anaerobic process

(B) It occurs in cytosol

(C) It contains no intermediates for Gluconeogenesis

(D) It is amphibolic in nature

37. How many ATP molecules will be required for conversion of 2-molecules of Lactic acid to Glucose? (A) 2 (B) 4 (C) 8 (D) 6

38. Out of 24 molecules of ATP formed in TCA cycle, 2 molecules of ATP can be formed at “substrate level” by which of the following reaction? (A) Citric acid→ Isocitric acid

(B) Isocitrate→ Oxaloacetate

(C) Succinic acid→ Fumarate

(D) Succinylcat→ Succinic acid

39. Which one of the following compounds cannot give rise to the net synthesis of Glucose? (A) Lactate (B) Glycerol

(C) α-ketoglutarate (D) Acetyl CoA

40. ‘Cori cycle is (A) Synthesis of glucose (B) reuse of glucose

(C) uptake of glucose (D) Both (A) & (B)

41. How many ATPs are produced in the conversion of phosphoenol pyruvate to citrate? (A) 1 (B) 2 (C) 4 (D) 6

42. The metabolite which sustains urea cycleis (A) Ornithine (B) Citrulline

(C) Carbamoyl phosphate (D) n-acetyl glutamate

43. Deamination is ______ of amino group. (A) Removal (B) Addition

(C) Supplementation (D) None of these

44. The transaminase activity needs the coenzyme: (A) ATP (B) B

+ 6– PO4 (C) FAD

+ (D) NAD

+

45. Transamination is a (A) Irreversible process (B) Reversible process

(C) Both (A) and (B) (D) None of these

46. Oxidative conversion of many amino acids to their corresponding –ketoacids occurs in mammalian: (A) Liver and kidney (B) Adipose tissue

(C) Pancreas (D) Intestine

47. Ammonia intoxication symptoms occur when brain ammonia levels are (A) Slightly diminished (B) Highly diminished

(C) Increased (D) All of these

Name: I.D.

3

48. Glutathione is a (A) Dipeptide (B) Tripeptide (C) Polypeptide (D) None of these

49. Urea biosynthesis occurs mainly in the liver involving the number of amino acids: (A) 3 (B) 4 (C) 5 (D) 6

50. Insulin is a protein which controls (A) Blood clotting (B) Metabolic pathway (C) Digestion (D) Kreb’s cycle

51. Pancreatic juice contains all of the following except (A) Trypsinogen (B) Lipase (C) Cholecystokinin (D) Chymnotrypsinogen

52. During glycolysis of glucose the energy liberated in the absence of oxygen is known as (A) Oxygenesis (B) Glyconeogenesis (C) Glycogenolysis (D) Anaerobic fermentation

53. Rennin acts on casein of milk in infants in presence of (A) Mg++ (B) Zn++ (C) Co++ (D) Ca++

54. A result of each oxidation a long chain fatty acid is cleaved to give (A) An acid with 3-carbon less and propionyl CoA (B) An acid with 2-carbon less and acetyl CoA

(C) An acid with 1-carbon less and acetyl CoA (D) An acid with 4-carbon and butyryl CoA

55. In β-Oxidation of fatty acids, which of the following are utilized as coenzymes? (A) NAD+ and NADP+ (B) FADH2 and NADH + H

(C) FAD and FMN (D) FAD+ and NAD+

56. The net number of ATP formed per mole of glucose in anaerobic glycolysis is (A) 1 (B) 2 (C) 6 (D) 8

57. The initial step of the citric acid cycle is (A) Conversion of pyruvate to acetyl-CoA (B) Condensation of acetyl-CoA with oxaloacetate

(C) Conversion of citrate to isocitrate (D) Formation of α -ketoglutarate catalyzed by isocitrate dehydrogenase

58. The hormone activating the glycogen synthase activity is (A) Insulin (B) Glucagon (C) Epinephrine (D) ACTH

59. Pancreatic lipase is activated in the presence of (A) Bile salts (B) Cu++ (C) K + (D) Na+

60. End product of aerobic glycolysis is (A) Acetyl CoA (B) Lactate (C) Pyruvate (D) CO2 and H2O

II. II. Answer the following: (30 Marks)

a) The role of hormones in the regulation of metabolism.

Hormones Carbohydrates Lipids

4

b) Compare between glycolysis and HMP-pathway.

Glycolysis HMP

Site

Function

ATP production

Hydrogen carrier

c) Compare between carrier protein and glutathione transport system in protein absorption.

Carrier protein transport system Glutathione transport system

With best wishes

Dr. Akaber Tarek