3rd Biochemistry Lecture Exam (Batch 2026) Flashcards by

1.The mechanism of action of toxicity of carbon monoxide is:

a.Binds to Cytochrome C Oxidase which results in impairment of NADPH synthesis

b.Reduced carrying capacity of hemoglobin for Oxygen through the formation of carboxyhemoglobin

c.Carbon monoxide alters the configuration of hemoqlobin lessening its affinity for oxygen

d.Carbon Plonoxide is a competitive inhibitor of oxygen

b.Reduced carrying capacity of hemoglobin for Oxygen through the formation of carboxyhemoglobin

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4.A four allele deletion will result in ,

a.Fetal hydrops

b.Asymptomatic

c.Cooley‘s Anemia

d.jaundice

a.Fetal hydrops

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5.First indicator of thalassemia

a.Low hemoglobin, Low hematocrit

b.Low Hemoglobin, Low WBC

c.Low NCV, Low hematocrit

d.Low MCV, Low hemoglobin

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6.Indicative of Thalassemia in peripheral blood smear

a.Nicrocytic cells

b.Normochromic cells

c.Anisocytosis

d.Decreased percentage of reticulocytes

c.Anisocytosis

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7.Which of the following statements is true regarding the ABO blood system?

a.People who have the A antigen normally would not produce the anti-A antibody

b.People who have the AB antigen normally would produce both anti-A and B antibodies

c.The only ABO type blood that normally does not have either A or B antigens is AB

d.None of the above

a.People who have the A antigen normally would not produce the anti-A antibody

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8.ABOi kidney transplantation is made possible because of

a.Desensitization protocols

b.Rituximab

c.Recombinant endo-B-gaIactosidase

d.Eculizimab

a.Desensitization protocols

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9.The disadvantage of plasma exchange as an antibody depletion strategy is

a.Loss of albumin

b.Loss of coagulation factors

c.Loss of anti-viral immunoglobulin

d.All of the above

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10.The replacement of ABO antigens that are compatible to the donated client to make ABOi kidney transplant possible is

a.Due to the presence of CD55 and CD59

b.Humoral immunity

c.Tolerance in ABO specific B cell elimination in the young

d.Endothelial Chimerism

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11.Presence of carbon monoxide poisoning results to which of the following?

A.Shifting of the oxygen dissociation curve to the left

B.Shifting of the oxygen dissociation curve to the right

C.Causes an increased delivery of oxygen to tissues

D.Decreases the oxygen affinity of the remaining 3 oxygen-binding sites

A.Shifting of the oxygen dissociation curve to the left

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12.Which can be omitted in managing patients with Thalassemia and other hemoglobinopathies?

A.Iron supplements

B.Folic Acid supplements

C.Blood transfusions

D.Chelation

A.Iron supplements

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13.This accounts for the largest fraction of total hemoglobin (90%):

A.HbA

B.HbF

C.HbA2

D. HbAlc

A.HbA

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14.What happens to the oxygen dissociation curve of an anemic patient?

A.There is a “shift to the left” with associated reduction of the affinity of hemoglobin to oxygen

B.There is a “shift to the left” with associated increase of the affinity of hemoglobin to oxygen

C.There is a “shift to the right” with associated reduction of the affinity of hemoglobin to oxygen

D.There is a “shift to the right” with associated increase of the affinity of hemoglobin to oxygen

C.There is a “shift to the right” with associated reduction of the affinity of hemoglobin to oxygen

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15.Which of the following Red Cell Indices show the differences in the sizes of Red Blood Cells?

A.Nean Corpuscular Volume

B.Red Cell Distribution Width

C.Mean Corpuscular Hemoglobin

D.Mean Corpuscular Hemoglobin Concentration

B.Red Cell Distribution Width

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16.Which statement is true regarding management of patients with carbon monoxide poisoning?

A.Oxygen is the most important treatment and is always indicated for at least 6 hours

B.Oxygen toxicity is likely with less than 24 hours of treatment.

C.Currently, the evidence for any treatment beyond 100% oxygen is very strong

D.All are correct

A.Oxygen is the most important treatment and is always indicated for at least 6 hours

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17.Which beta thalassemia syndrome is characterized by frequent transfusions, marked

hepatosplenomegaly, craniofacial changes, and stunting of growth:

A.Thalassemia intermedia

B.Thalassemia major

C.Silent carrier

D.Thalassemia trait

B.Thalassemia major

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18.This hemoglobin is markedly elevated in Beta thalassemia major:

A.Hb A1

B.Hb A2

C.Hb F

D.Hb H

C.Hb F

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19.Currently, the only cure available to patients with sickle cell disease

A.Crizanlizumab

B.Stem Cell Transplantation

C.Hydroxyurea

D.Gene therapy

B.Stem Cell Transplantation

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20.The mode of inheritance of Beta thalassemia major is:

A.Autosomal dominant

B.Autosomal recessive

C.X-linked recessive

D.De novo mutation

B.Autosomal recessive

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21.Which amino acid is commonly formed in many transamination reactions?

A.Alanine

B.Aspartate

C.Glutamate

D.Lysine

C.Glutamate

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22.The intermediates named are generated from Cysteine, EXCEPT?

A.taurine

B.mercaptoethanolamine

C.melanin

D.pyruvate

C.melanin

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23.Which of the following amino acids is NOT a donor of one carbon compound?
A.Histidine

B.Tyrosine

C.Tryptophan

D.Serine

B.Tyrosine

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24.In mammalian cells, Ser can be a biosynthetic substrate for the synthesis of what amino acid?

A.Nethionine

B.Lysine

C.Arginine

D.Glycine

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25.Which coenzyme is used by serine hydroxymethyltransferase acting on Serine?

A. N5N10 methylene tetrahydrofolate
B. Tetrahydrofolate
C. Formyl tetrahydrofolate
D. Methyl tetrahydrofolate

B.Tetrahydrofolate

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26.Dioxyphenylakanine is synthesized from which of the amino acids named:
A.Tyrosine

B.Tryptophan

C.Histidine

D.Nethionine

A.Tyrosine

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27.Which is the coenzyme and its precursor used in transamination reactions? A.NAD+/vitamin B3 B.FAD/vitamin B2 C.pyridoxal PO4/vitamin B6 D.cobalamin/vitamin B12

C.pyridoxal PO4/vitamin B6

28.Why is Histidine classified as a glucogenic amino acid? A.it‘s degraded to a-ketoglutarate B.upon its breakdown it gives rise to acetyl CoA C.a product of its oxidation is pyruvate D.it produces alanine

A.it‘s degraded to a-ketoglutarate

29.What is the defect in a child with non-classic PKU? A.deficiency of phenylalanine hydroxylase B.a lack of dihydrobiopterin reductase C.a defect on tyrosine transaminase D.a mutated fumarylacetoacetate hydrolase

B.a lack of dihydrobiopterin reductase

30.Which is the most common pair used in transamination reaction? A.a ketoglutarate/glutamate pair B.pyruvate/alanine pair C.oxaloacetate/aspartate pair D.a ketobutyrate/malate pair

A.a ketoglutarate/glutamate pair

31.Food products containing which of the following are advised not to be consumed by persons with classic type of PKU? A.Oleomarqarine B.Crisco C.Sprye D.Aspartame

D.Aspartame

32.If an amino acid upon degradation of its carbons generates aceoacety CoA and fumarate, it is classified as: A.glucogenic amino acid B.ketogenic amino acid C.both glucogenic/ketogenic amino acid D.essential amino acid

C.both glucogenic/ketogenic amino acid

33.Which amino acid whose carbons upon degradation gives rise to acetoacetate: A.Leucine B.Serine C.Asparagine D.Methionine

A.Leucine

34.Which metabolic abnormality gives rise to the serious disease phenylketonuria? A.Homocysteine cannot be converted into methionine B.Phenylalanine cannot be converted into tyrosine C.Phenylalanine cannot be converted into alanine D.Tyrosine cannot be converted into phenylalanine

B.Phenylalanine cannot be converted into tyrosine

35.In Naple Syrup Urine Disease, the enzyme deficient is: A.a-keto acid dehydrogenase B.branched-chain amino acid transaminase C.§-methyIcrotonyI CoA dehydrogenase D.enoyl CoA hydratase

A.a-keto acid dehydrogenase

36.Which is the disease brought about by a mutation affecting the gene that codes for the enzyme homogentisic acid oxidase? A.tyrosinemia type I B.Richner-Hanhart syndrome C.tyrosinemia type II D.alkaptonuria

D.alkaptonuria

37.Which causes Tyrosinemia Type I? A.fumarylacetoacetate hydrolase deficiency B.lack of phenylalanine hydrolase C.absence of cystathionine §-synthase D.defect in homogentisate oxidase structure

A.fumarylacetoacetate hydrolase deficiency

38.Which amino acid is used to synthesize Adomet? A.Cys B.Met C.Ser D.Ala

B.Met

39.Which is the fate of the sulfate generated In the metabolism of cysteine? A.incorporated into other substrates B.liberated unchanged C.used in the synthesis of PAPS D.incorporated into glucose to form cerebrosides

C.used in the synthesis of PAPS

40.Which is substrate of nitric oxide synthase (NOS) generating NO, an endothelial relaxing factor? A.Asn B.Lys C.Asp D.Arg

D.Arg

41.Which reaction converts Histidine to Histamine during an allergic reaction? A.decarboxylation B.reduction C.oxidation D.hydroxylation

A.decarboxylation

42.Which neurotransmitter is formed from decarboxylation of glutamate? A.serotonin B.dopamine C.y-amino but:yric acid D.neurotensin

C.y-amino but:yric acid

43.Which is required by phenylethanolamine N-methyl transferase in synthesizing adrenaline from noradrenaline? A.S-adenosyl methionine B.methyl cobalamin C.3’-phosphoadenosine-5‘-phosphosulfate D.5-deoxyadenosyI cobalamin

A.S-adenosyl methionine

44.Which is the nitrogen donor in the synthesis of asparagine? A.Glutamine B.Ammonia C.Glycine D.Tyrosine

A.Glutamine

45.Which amino acid when its amino group is used in a reaction gives rise to fumarate? A.Aspartate B.Nethionine C.Glutamine D.Arginine

A.Aspartate

46.Which kind of glycosidic bond forms the amylose portion of glycogen? A.alpha 1,4 B.beta 1,4 C.alpha 1,2 D.beta 1,3

A.alpha 1,4

47.Which bond in glycogen makes the limit dextrin part of glycogen? A.alpha 1,4 B.beta 1,4 C.alpha 1,6 D.beta 1,3

C.alpha 1,6

48.Which is the major key regulatory enzyme in glycogenolysis? A.glycogen phosphorylase kinase B.amylo a 1,4 to a 1,4 glucan transferase C.a 1,6 glucosidase D.glycogen phosphorylase

D.glycogen phosphorylase

49.At which part of glycogen does glycogen phosphorylase removes one glucose unit at a time? A.reducing end at anomeric carbon B.non-reducing end at C4 C.sixth carbon having the alcohol group D.branches having the alpha 1,6 glycosidic bond

B.non-reducing end at C4

50.These factors/molecules allosterically modifies muscle glycogen phosphorylase EXCEPT: A.ATP B.AMP C.Glucose D.Glucose 6-PO4

C.Glucose

51.Which is the major key regulatory enzyme used in glycogenesis? A.glycogen synthase kinase B.glycogen synthase C.amylo a 1,4 to a 1,4 glucan transferase D.amylo a 1,4 to a 1,6 glucan transferase

B.glycogen synthase

52.Which is the amino acid residue of glycogenin to attach the first activated glucose? A.Y B.K C.D D.Q

A.Y

53.Which hormone predominates when cells are in mode of depositing glucose as glycogen? A.epinephrine B.glucagon C.insulin D.adrenaline

C.insulin

54.Which two hormones favors glycogenolysis? A.epinephrine/glucagon B.adrenaline/estradiol C.insulin/glucagon D.epinephrine/insulin

A.epinephrine/glucagon

55.Which enzyme directly modifies muscle glycogen phosphorylase? A.glycogen synthase kinase B.protein kinase A C.phosphorylase kinase D.adenylate kinase

C.phosphorylase kinase

56.Which is the active form of glycogen synthase? A.phosphorylated B.the tense state C.with attached PO4 group D.dephosphorylated

D.dephosphorylated

57.Which is the modified form of glycogen phosphorylase? A.phosphorylated B.the tense state C.without attached PO4 group D.dephosphorylated

A.phosphorylated

58.Which enzyme coordinates the need for calcium and energy used for muscle contraction? A.glycogen phosphorylase B.glycogen synthase kinase C.glycogen phosphorylase kinase D.alpha 1,6 glucosidase

C.glycogen phosphorylase kinase

59.When is glycogen phosphorylase kinase fully activated? A. § subunit bound to Ca2+ & a subunit phosphorylated C. a subunit bound to Ca2+ & d subunit phosphorylated B. § subunit phosphorylated & 6 subunit bound to Ca2+ D. y subunit phosphorylated & § subunit bound to Ca2+

B. § subunit phosphorylated & 6 subunit bound to Ca2+

60.Which reaction is catalysed by glycogen phosphorylase? A.phosphorolysis B.hydrolysis C.aldol condensation D.isomerization

A.phosphorolysis

61.Why is glycogen as granule has many tiers/branches? A.more non-reducing ends for faster breakdown B.more reducing ends for faster synthesis C.increasing the insolubility of the molecule D.decreasing the solubility of the polymer

A.more non-reducing ends for faster breakdown

62.Which is the product of glycogen phosphorylase? A.glucose 6-PO4 B.fructose 1-PO4 C.free glucose D.glucose 1-PO4

D.glucose 1-PO4

63.Which is the main function of the degradation of glycogen in the liver? A.to supply of energy to the liver cells B.to maintain the level of blood glucose to normal C.to export glucose to the muscle tissue D.to solely supply the brain with the source of energy

B.to maintain the level of blood glucose to normal

64.Glycogen phosphorylase stops when there are how many glucosyl units from an a 1,6 glycosidic bond? A.two B.three C.four D. six

C.four

65.When the activity of glycogen phosphorylase stops near a branching point in glycogen, what polymer of glucose is formed? A.amylose B.amylopectin C.maltodextrin D.limit dextrin

D.limit dextrin

66.Which is the enzyme activated during the fed state favoring deposition of glucose as glycogen? A.phosphodiesterase B.protein phosphatase C.adenlyl cyclase D.phosphatase kinase

B.protein phosphatase

67.Why is the product of glycogen breakdown in the muscle can’t be used by other tissues like the brain for its energy needs? A.absence of glucose 6-phosphatase B.defective pyruvate carboxylase C.mutated glucokinase D.deficient PEP carboxykinase

A.absence of glucose 6-phosphatase

68.An infant was brought to the emergency room after her parents witnessed her having seizures. The child’s blood glucose was 28mmo;/L/ After a thorough workup, a glycogen storage disease (GSD) was suspected, and a muscle biopsy was significant for the accumulation of dextrin, a form of glycogen with branching limited to only a few glucose molecules. Which of the following GSD is most likely the cause of hypoglycemia and subsequent seizures? A.Type I — von Gierke’s disease B.Type II — Pompe’s disease C.Type III — Cori’s disease D.Type IV — Andersen‘s disease

C.Type III — Cori’s disease

69.A glycogen storage disease that involves a deficiency of a unique enzyme of gluconeogenesis: A.Pompe‘s B.von Gierke’s C.Anderson‘s D.Her‘s

B.von Gierke’s

70.In which organ and which enzyme deficiency causes NcArdle’s disease? A.Glycogen phosphorylase, liver B.Glycogen phosphorylase, muscle C.debranching enzyme, liver D.debranching enzyme, muscle

B.Glycogen phosphorylase, muscle

71.L-glucose and D-glucose are pairs of structures that are mirror images of each other. These are examples of: a.isomers b.epimers c. enantiomers d. anomers

c. enantiomers

72.This 3 carbon monosaccharide is an intermediate in glycolytic and pentose phosphate pathway. a.gIyceraIdehyde b.erthyrose c.dihydroxyacetone d.glucose

a.gIyceraIdehyde

73.The monosaccharides glucose and fructose linked by glycosidic bonds form which sugar: a.Lactose b.Maltose c.Sucrose d.Fructose

c.Sucrose

74.This sugar derivative is vital in the synthesis of collagen. a.Glucuronic acid b.hyalouronic acid c.Ascorbic acid d.Sorbitol

c.Ascorbic acid

75.Major storage form of energy in the body. a.glycogen b.glucose c. cellulose d. starch

a.glycogen

76.Compounds having same structural formula but differing in configuration around one carbon atom are a.epimers b.enantiomers c.stereoisomers d.optical isomers

a.epimers

77.The polysaccharide found in the cell wall of insects is: A.Chitin B.Ground substance C.Hyaluronic acid D.Collagen

A.Chitin

78.Aldose reductase is an enzyme abundant in the following tissues except: a.liver b.nerve tissue c. seminal vesicles d. muscles

d. muscles

79.Which of the following compounds is not produced from dietary starch by salivary a-amylase? a.fructose b. maltose c. isomaltose d. maltotriose

d. maltotriose

80.Digestion in the mouth starts with this enzyme cleaving the bonds of dietary starch and glycogen in a random manner requiring an optimum pH. a.ptyalin b.maltotriose c.dextrin d.isomaltase

a.ptyalin

81.Absence of this enzyme causes dietary cellulose to remain undigested. a.glucoamylase b.sucroamylase c.lactose B-glycosidase d.trehalase

c.lactose B-glycosidase

82.Cataract formation in Diabetes is brought about by accumulation of sorbitol in the lens. This is secondary to interaction between blood glucose and: a.NADPH -dependent aldose reductase b.glucokinase c.hexokinase d. phosphoglucoisomerase

a.NADPH -dependent aldose reductase

83.Glucose is maintained in the blood as the sole energy source for the in the non-starving state and as an available energy source for all other tissues a.liver b.brain c.lungs d.kidneys

b.brain

84.Special type of isomerism found in structures that are mirror images of each other; vast majority in humans are D-sugars a.epimers b.enantiomers c.stereoisomers d.anomers

b.enantiomers

85.This is the transport system for fructose and mannose involving formation of an intermediate complex with a specific carrier protein: , a.simple diffusion b.facilitated diffusion c.active transport d. passive transport

b.facilitated diffusion

86.The carbonyl carbon, either aldehyde or keto group , undergo this process to produce a new alcohol group. Fructose go through this process to form sorbitol and mannitol. a.Oxidation b.Reduction c.Mutarotation d.Conformation

b.Reduction

87.Which of the following is correct? a.The Fischer projection is the representation of the cyclic sugar where carbon 1 is the farthest to the right, the plane of the ring is flat. b.Glycogen is synthesized from Beta-D-gIucopyranose. c.The noncarbohydrate portion of the complex carbohydrate molecule is called the aglycone. d.Lactose and sucrose are both reducing sugars.

c.The noncarbohydrate portion of the complex carbohydrate molecule is called the aglycone.

88.The principal sites of dietary carbohydrate digestion are: a.mouth and intestinal lumen b.duodenum and jejunum c.mouth and stomach d. stomach and intestinal lumen

a.mouth and intestinal lumen

89.Glycosaminoglycans are large complexes of negatively charged heteroplohysaccharides that stabilize and support cellular and fibrous components of tissues while maintaining water and salt balance. The most abundant glycosaminoglycan in the body is: a.Keratan sulfate b.Hyaluronic acid c.Chondroitin sulfate d.Dermatan sulfate

c.Chondroitin sulfate

90.The only tissue with glycerol kinase to phosphorylate glycerol. a.brain b.liver c.pancreas d.small intestines

b.liver

91.Which antigen is present if the blood type is 0? a.A antigen b.B antigen c.H antigen d.BothAand B

c.H antigen

92. In individuals with blood type A, what do you call the terminal carbohydrate forming the antigen of blood A? , a.§-n-acetyIgaIactosamine b.a-1,3-n-acetyIgaIactosaminyItransferase c.a-d-galactose d.both A and B

a.§-n-acetyIgaIactosamine

93.In individuals with blood type B, what do you call the terminal carbohydrate forming the antigen of blood B? a.§-n-acetyIgaIactosamine b.a-1,3-n-acetyIgaIactosaminyItransferase c.a-d-galactose d.none of the above

c.a-d-galactose

94.Which blood type will have lower immunologic risk associated with ABO incompatibility in kidney transplant (mainly because 80% of individuals will have a certain subtype)? a.Blood group A b.Blood goup B c.Blood group AB d.Blood group O

a.Blood group A

95.When is/are desensitization protocol/s done on the patient? a.Before the transplant b.After the transplant c.Never Both A and B

Both A and B

96.A type of structural polysaccharide that is a complex polyphenoic subs%nce found in wood: a.Hemicelluloses b.lignin c.pectin d.inulin

b.lignin

97.Proteolgylcans are assembled through a series of reactions in the: , a.Endoplasmic reticulum & Golgi apparatus b.Cytosol and Golgi apparatus c.Mitochondria and ER d.Cytosol & ER

a.Endoplasmic reticulum & Golgi apparatus

98.Assymetric mixed acteals formed by the reaction of the anomeric carbon furnished by an alcohol group. a.Glycosides b.Glycoproteins c.Sugar alcohol d.Deoxysugars

a.Glycosides

99.Nost heterogenous glycosaminoglycan found in cartilage and aggreagates and also in the cornea a.Keratan sulfate b.Hyaluronic Acid c.Heparin sulphate d. Chondroitin sulfate

a.Keratan sulfate

100.Hexosamines formed through substitution of an amino group for a hydroxyl group on the sugar ring a.Sugar phosphate b.Deoxysugars c.Aminosugars d.Sugar acids

c.Aminosugars

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3rd Biochemistry Lecture Exam (Batch 2026) Flashcards

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