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13. Urobilinogen is formed in:

a) The gall bladder

b) The reticuloendothelial system

c) Erythrocytes

d) The liver parenchymal cells

e) The gut24. Lead poisoning characteristically leads to inhibition of the following:

a) Uroporphyrinogen decarboxylase

b) ALA dehydratase

c) ALA synthase and ferrohectase

d) Porphobilinogen deaminase

e) Bilirubin reductase and eoproporphyrin

25. In acute intermittent porphyria the appearance of high levels of delta-

aminolevulinic acid and porphobilinogen in the urine is due to deficiency of the

following enzyme:

a) Delta aminolevulinate synthase b) Delta aminolevulinate dehydratase

c) Uroporphyrinogen I synthase

d) Ferrochelastase

e) Microsomoal heme oxygenase

26. Increased excretion of urobilinogen is most likely caused by:

a) Erythropoetic porphyria

b) Liver disease such as viral hepatitis

c) Hemolysis

d) Iron deficiency

e) Common bile duct obstruction

27. An increase in plasma conjugated bilirubin concentration is most often

associated with:

a) Increased heme synthesis

b) Erythropoetic porphyria

c) Viral hepatitis

d) High level of bilverdin

e) Common bile duct obstruction

28. The formation of bilirubin from heme:a) Requires oxygenase

b) Requires bilverdin reductase

c) Occurs in the reticuloendothelial system

d) Releases carbon monoxide and iron

e) All of the above

29. The commited step in heme biosynthesis produces:

a) ALA

b) Porphobilinogen

c) Protoporphyrinogen

d) Uroporphyrinogene) Hydroxymethylbilane

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30. The immediate precursor of heme in its biosynthesis is:

a) Protoporphyrin IIIb) Coproporphyrinogen III

c) Protoporphyrinogen

d) Prophobilinogen

e) Urobilin

31. Urobilinogen in the intestine is:

a) Synthesized from conjugated bilirubin

b) Converted to urobilin in stools

c) Reabsorbed in the terminal ileum and large intestine

d) Colourless

e) All of the above

40. In hemoglobin S the mutation in the beta chain results from:

a) Insertion of a nucleotide

b) Replacement of alanine by serine in position 6

c) Deletion of a nucleotide

d) Replacement of glutamate by valine in position 6

e) A and C are correct

43. Urobilinogen is detected in the urine of a patient with:

a) Obstructive jaundice

b) Hemolytic jaundice

c) Hepatocellular jaundice

d) Acute pancreatitis

e) None of the above is correct

45. The immediate precursor of heme in its biosynthesis is:

a) Protoporphyrin IX

b) Coproporphhyrinogen III

c) Protoporphyrinogen IX

d) Porphobilinogene) Urobilin

46. The cells which are very active in heme biosynthesis include:

a) Erythroid precursors

b) The liver cells

c) Adipose tissue cells

d) Cardiac muscles

e) Intestinal mucosal cells

]

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29. The following statements are true:

a) Transferrin transports calcium in the circulation

b) Hemochromatosis is characterized by excessive storage of ions in tissues

c) Haptoglobin binds extra corpuscular hemoglobin

d) All of the above is correct

e) B and C are correct

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