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Biochem lecture quizzes compiled

Aneesa Sukhai 90 questions

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Questions in this quiz (90)

1Nonpolar amino acids
1. AAccept protons as strong base
2. Brelease protons as strong acids
3. Cas usually found in the interior of proteins in aqueous environments
4. Dparticipate in hydrogen and ionic bonds
2A 2-year old child presents with metabolic acidosis after ingesting an unknown number of flavored aspirin tablets. At presentation, her blood pH was 7.0. Given that the pKa of aspirin (Salicylic acid) is 3, calculate the ratio of its ionized to un-ionized forms at pH 7.0 Hint: pH = pKa + log [Ionized form]/[Unionized form]
1. A10
2. B100
3. C1,000
4. D10,000
3The pKa of an amino acid is:
1. Athe pH at which the amino acid provides minimal buffering capacity.
2. Bthe pH where the protonated acid predominates.
3. Cthe pH where the deprotonated base predominates.
4. Dthe pH at which the concentration of the weak acid and its conjugate base are equal.
4Given that the pI of glycine is 6.1, to which electrode, positive (anode) or negative (cathode) will glycine migrate to in an electric field at pH 2?
1. APositive (anode)
2. BNegative (cathode)
3. CGlycine will not migrate to either the negative or positive pole.
4. DGlycine will precipitate into a solid at this pH.
5Proteins are:
1. Alinear polymers of amino acids arranged in a specific order and length.
2. Bcomposed of 50 different amino acids in humans.
3. Cdifferent linear combinations of amino acids joined by glycosidic bonds.
4. Dfolded into random 3 dimensional structures.
6A particular point mutation results in disruption of the -helix in a segment of the mutant protein. The most likely change in the primary structure of the mutant protein is:
1. Aglutamate to aspartate.
2. Blysine to arginine
3. Cmethionine to proline.
4. Dvaline to alanine.
7A peptide bond:
1. Ahas a partial double bond character
2. Bis ionized at physiological pH.
3. Cis stable to heating in strong acids.
4. Doccurs most commonly in the cis configuration.
8An 80-year old man presented with impairment of higher intellectual function and alterations in mood and behaviour. His family reported progressive disorientation and memory loss over the last 6 months. There is no family history of dementia. The patient was tentatively diagnosed with Alzheimer disease. Which one of the following best describes Alzheimer disease?
1. AIt is associated with beta-amyloid, an abnormal protein with an altered amino acid sequence.
2. BIt results from accumulation of denatured proteins that have random conformations.
3. CIt is associated with the accumulation of amyloid precursor protein.
4. DIt is associated with the deposition of neurotoxic amyloid beta peptide aggregates
9Which one of the following statements concerning the binding of oxygen to hemoglobin is correct?
1. ACarbon dioxide increases the oxygen affinity because it increases the pH
2. BHemoglobin binds 4 molecules of 2,3-BPG
3. CThe binding of oxygen at one heme group increases the oxygen affinity of the remaining heme groups
4. DOxyhemoglobin and deoxyhemoglobin have the same affinity for protons.
10Beta-lysine 82 in HbA is important for the binding of 2,3-bisphosphoglycerate (BPG). In Hb Helsinki, this amino acid has been replaced by methionine. Which of the following should be true concerning Hb Helsinki?
1. AIt should be stabilized in the taut rather than the relaxed form
2. Bit should have increased O2 affinity and consequently decreased delivery of O2 to tissues
3. Cits O2 dissociation curve should be shifted to the right relative to HbA
4. Dit results in anemia

11Sickle cell anemia:
1. Ais the least common of the red cell sickling diseases
2. Bis a genetic disorder caused by a single nucleotide alteration in the beta-globin gene
3. Coccurs in individuals who have inherited one mutant gene coding for the synthesis of the beta-chains of globin molecules
4. Dis a hereditary haemolytic disease in which an imbalance occurs in the synthesis of globin chains
12Carbon monoxide binding to hemoglobin:
1. Aresults in the formation of methemoglobin
2. Bis characterized by low affinity for CO (does not displace oxygen)
3. Cshifts the oxygen dissociation curve to the left
4. Dchanges the normal hyperbola shape of the oxygen dissociation curve toward a sigmoidal shape
13Collagen:
1. Ais an example of a globular protein
2. Bis the least abundant protein in humans
3. Cis rich in the amino acids serine and glutamate
4. Dis a rigid structure in which 3 protein chains are wound around each other in a triple helix
14Elastin:
1. Ais a connective tissue protein with 'rubber-like' properties
2. Bis composed of an abundance of hydroxyproline and hydroxylysine
3. Ccannot stretch or bend in any direction when stressed, giving connective tissue rigidity
4. Dis a soluble protein polymer synthesized from the precursor, tropocollagen
15A 30-year old woman of Northern European ancestry presents with progressive dyspnea (Shortness of breath). She denies the use of cigarettes. Family history reveals that her sister also has problems with her lungs. Which one of the following scenarios most likely explains this patient’s pulmonary symptoms?
1. Adeficiency of dietary vitamin c
2. Bdeficiency of alpha1-antitrypsin
3. Cdeficiency of prolyl hydroxylase
4. Ddecreased elastase activity
16Enzymes:
1. Aare protein catalysts that increase the velocity of chemical reactions.
2. Bdo not change the free energy of activation of a chemical reaction
3. Care altered during the chemical reaction(s) they catalyze.
4. Dchange the free energies of the substrate (Reactant) and product
17For enzymes that may be modelled using Michaelis-Menton kinetics describing how reaction velocity (Vo) varies with [Substrate], when the [Substrate] = Km (Michaelis constant), then:
1. AVo = 0
2. BVo = ¼ Vmax
3. CVo = ½ Vmax
4. DVo = Vmax
18In cases of ethylene glycol poisoning and its characteristic metabolic acidosis, treatment involves correction of the acidosis, removal of any remaining ethylene glycol, and administration of an inhibitor of alcohol dehydrogenase (ADH), the enzyme that oxidizes ethylene glycol to the organic acids that cause the acidosis. Ethanol (Grain alcohol) frequently is the inhibitor given to treat ethylene glycol poisoning; it works by competitively inhibiting ADH. As a competitive inhibitor, ethanol:
1. Aincreases Km without affecting Vmax
2. Bdecreases Km without affecting Vmax
3. Cincreases Vmax without affecting Km
4. Ddecreases Vmax without affecting Km
19Alcohol dehydrogenase (ADH) requires NAD+ for catalytic activity. In the reaction catalyzed by ADH, an alcohol is oxidized to an aldehyde as NAD+ is reduced to NADH and dissociates from the enzyme. The NAD+ is functioning as (an):
1. Aheterotropic effector
2. Bcofactor.
3. Capoenzyme.
4. Dcoenzyme-cosubstrate
20For enzymes that obey Michaelis-Menton kinetics, a plot of [Substrate] versus Reaction Velocity (Vo) is hyperbolic in shape. When the [Substrate] is much greater than Km,
1. AVo is independent of [Substrate] or zero order.
2. BVo is dependent of [Substrate] or first order.
3. CVo is dependent of [Substrate] or zero order.
4. DVo is independent of [Substrate] or first order.
21The change in free energy (ΔG) occurring during a chemical reaction:
1. Adoes not predict the direction the reaction will spontaneously proceed.
2. Bis not dependent on the change of enthalpy (ΔH).
3. Cis not dependent on the change of entropy (ΔS).
4. Dpredicts the direction in which the reaction will spontaneously proceed.
22As electrons are passed down electron transport chain, free energy is captured and stored as ATP formed from ADP and Pi by a process termed:
1. Aglycolysis
2. Boxidative phosphorylation
3. Cthe tricarboxylic acid (TCA) cyle
4. Dgluconeogenesis
23Electron transport coupled to transport of protons (H+) out of the mitochondrial matrix and into the intramembrane space creates:
1. Aenergy
2. BATP
3. CADP
4. Dan electrical and a pH gradient
24A muscle biopsy from a patient with a rare disorder, Luft disease, showed abnormally large mitochondria that contained packed cristae when examined in the electron microscope. Basal ATPase activity of the mitochondria was seven times greater than normal. From these and other laboratory results, it was concluded that oxidation and phosphorylation were partially uncoupled. Which of the following statements about this patient is correct?
1. AATP levels in the mitochondria are greater than normal.
2. BThe rate of electron transport is abnormally low.
3. CThe patient shows hypermetabolism and elevated core body temperature.
4. DThe proton gradient across the inner mitochondrial membrane is greater than normal.
25Carbon monoxide (CO) binds to and inhibits Complex IV of the electron transport chain. What effect, if any, should this respiratory inhibitor have on oxidative phosphorylation?
1. ACO will activate the electron transport chain by increasing the proton gradient resulting in activation of oxidative phosphorylation.
2. BCO will inhibit the electron transport chain by increasing the proton gradient resulting in activation of oxidative phosphorylation.
3. CCO will inhibit the electron transport chain by disrupting the proton gradient resulting in inhibition of oxidative phosphorylation.
4. DCO will have no effect on the electron transport chain and oxidative phosphorylation.
26Which of the following statements best describes glucose?
1. AIt is a ketose and usually exists as a furanose ring in solution.
2. BIt is a C-4 epimer of galactose
3. CIt is utilized in biological systems only in the L-isomeric form
4. DIt is produced from dietary carbohydrates by the action of salivary -amylase.
27Sugars may be attached to an – NH2 or a – OH group of non-carbohydrate molecules to produce:
1. AN- and O-glycosides.
2. Bpolysaccharides.
3. Clipids.
4. Dproteins.
28A young black man entered his physician’s office complaining of bloating and diarrhea. His eyes were sunken and the physician noted additional signs of dehydration. The patient’s temperature was normal. The patient explained that the episode has occurred following a birthday party at which he had participated in an ice cream eating contest. The patient reported prior episodes of a similar nature following ingestion of a large amount of dairy products. This clinical picture is most probably due to a deficiency in:
1. Apancreatic alpha-amylase.
2. Bsalivary alpha-amylase.
3. Csucrase
4. Dlactase
29Routine biochemical examination of the urine from an asymptomatic pediatric patient showed a positive reaction with Clinitest (A copper reduction method of detecting reducing sugars such as glucose, fructose, lactose, galactose), but a negative reaction with the glucose oxidase test. Which one of the following sugars is least likely to be present in the urine assuming a single elevated saccharide?
1. AFructose
2. BLactose
3. CSucrose
4. DGalactose
30The final digestive processes of carbohydrates occur:
1. Ain the liver
2. Bin the stomach
3. Cin the pancreas
4. Dat the mucosal lining of the small intestine
31Which of the following statements concerning glycolysis is correct?
1. AThe conversion of glucose to lactate requires the presence of oxygen
2. BThe regulated reactions are also the irreversible reactions
3. CThe conversion of glucose to lactate yields 2 ATP and 2 NADH
4. DFructose 2,6-bisphosphate is a potent inhibitor of phosphofructokinase
32Aerobic glycolysis:
1. Ais an example of an anabolic pathway.
2. Bdoes not require an adequate supply of oxygen.
3. Cdescribes the conversion of glucose to lactate.
4. Dresults in the production of NADH and ATP.
33The reaction catalyzed by phosphofructokinase:
1. Ais activated by high concentrations of ATP and citrate
2. Bis inhibited by fructose 2,6-bisphosphate
3. Cis the rate limiting reaction of glycolysis
4. Dis near equilibrium in most tissues
34Compared with resting skeletal muscle, vigorously contracting skeletal muscle shows:
1. Aa decreased NADH/NAD+ ratio
2. Ba decreased rate of pyruvate oxidation
3. Ca decreased concentration of AMP
4. Dan increased conversion of pyruvate to lactate
35The tricarboxylic acid (TCA) cycle:
1. Aoccurs in the cytoplasm.
2. Bdoes not provide the energy for the production of the majority of ATP in humans
3. Cutilizes CO2 as the major fuel or substrate
4. Dis an aerobic pathway because oxygen is required as the final electron acceptor.
36Which one of the following conditions decreases the oxidation of acetyl CoA by the TCA cycle?
1. AA low ATP/ADP ratio
2. BA low NADH concentration due to rapid oxidation to NAD+ by the electron transport chain
3. CA low concentration of AMP
4. DA low NAD+/NADH ratio
37The 3 most important enzymes that regulate the activity of the TCA cycle are:
1. Acitrate synthase, isocitrate dehydrogenase, and alpha-ketoglutarate dehydrogenase.
2. Baconitase, succinate thiokinase, and fumarase.
3. Cmalate dehydrogenase, succinate dehydrogenase, and fumarase.
4. Daconitase, malate dehydrogenase, and succinate dehydrogenase.
38The pyruvate dehydrogenase complex which catalyzes the conversion of pyruvate to acetyl CoA is:
1. Aan enzyme composed of a single protein subunit and a single coenzyme.
2. Binactivated by elevated levels of acetyl CoA and/or NADH.
3. Cnot regulated by phosporylation and a dephosphorylation.
4. Dis inactivated by calcium.
39Gluconeogenesis:
1. Aoccurs solely in the cytoplasm.
2. Bdescribes the conversion of pyruvate to glucose.
3. Coccurs by a simple reversal of the reactions of glycolysis.
4. Doccurs primarily in the brain and heart.
40The synthesis of glucose from pyruvate by gluconeogenesis:
1. Aoccurs exclusively in the cytoplasm.
2. Brequires FAD.
3. Cinvolves lactate as an intermediate.
4. Dis activated by an elevated level of glucagon.
41Which of the following statements concerning gluconeogenesis is correct?
1. AIt occurs in skeletal muscle.
2. BIt is inhibited by elevated levels of acetyl CoA.
3. CIt is important in maintaining blood glucose during a normal overnight fast.
4. DIt uses carbon skeletons provided by degradation of fatty acids.
42In a glucose tolerance test, an individual in the basal metabolic state ingests a large amount of glucose. If the individual is normal, this ingestion should result in which of the following?
1. AAn increase in cAMP levels in the liver
2. BAn increased ratio of glycogen phosphorylase to glycogen synthase in the liver.
3. CAn increase rate of lactate formation by red blood cells.
4. DAn enhanced glycogen synthase activity in the liver.
43Regulation of glycogen synthesis and degradation is accomplished by:
1. Athe hormonal regulation of glycogen synthase and glycogen phosphorylase.
2. Ballosteric regulation to meet the demands of a particular tissue.
3. CBoth A and B.
4. DNeither A or B.
44The main storage sites for glycogen are:
1. Askeletal muscle and the liver.
2. Bthe brain and kidney.
3. Cthe heart and lungs.
4. Dthe pancreas and stomach.
45Glycogen:
1. Ais stored primarily in the brain.
2. Bfrom the liver serves as a fuel reserve for synthesis of ATP.
3. Cis a branched-chain polysaccharide made exclusively from alpha-D-glucose.
4. Dfrom skeletal muscle maintains the blood glucose concentration during a fast.
46The digestion of dietary lipids in humans:
1. Astarts in the mouth and continues in the large intestine.
2. Bstarts in the stomach and continues in the small intestine.
3. Cstarts in the small intestine and ends in the large intestine.
4. Dstarts in the mouth and ends in the small intestine.
47Enzyme-catalyzed breakdown of dietary lipids requires emulsification which is accomplished by:
1. Adigestive enzymes and fatty acids.
2. Ban aqueous environment and potassium chloride.
3. Ccholesterol esters and phospholipids.
4. Dbile salts and mechanical mixing.
48The major enzymes in humans that breakdown triacylglycerol, phospholipids, and cholesterol esters in the small intestine are:
1. Alingual lipase and gastric lipase.
2. Bpancreatic lipase, phospholipase A2, and cholesteryl esterase.
3. Cfatty acyl-CoA synthetase and acyl CoA: monoacylglycerol acyltransferase.
4. Dacyl CoA cholesterol acyltransferase and pepsin.
49What are the major products generated from enzyme-catalyzed breakdown of dietary lipid?
1. Aglycerol 3-phospahte, glucose, and glycine.
2. Bglycerol, amino acids, and cholesterol.
3. Cfree fatty acids, 2-monoacylglycerol, and cholesterol.
4. Dfree fatty acids, amino acids, and cholesterol.
50Free fatty acids, 2-monoacylglycerol, unesterified cholesterol, and fat soluble vitamins form mixed micelles that promote:
1. Acholesterol absorption by the pancreas.
2. Bfatty acid absorption by the stomach.
3. Cglycerol absorption by the liver.
4. Ddietary lipid absorption by intestinal mucosal cells.
51Which of the following statements about the digestion of lipids is correct?
1. ALipid digestion begins with acid-stable lipases that primarily use triacylglycerol (TAG) with long to very long-chain fatty acids as substrates.
2. BLarge lipid droplets are emulsified (have their surface area increased) in the mouth through the act of chewing (mastication).
3. CPatients with cystic fibrosis have difficulties with digestion because their thickened pancreatic secretions are less able to reach the small intestine, the primary site of lipid digestion.
4. DFormation of chylomicrons is independent of protein synthesis in the intestinal mucosa.
52Which of the following statements about the absorption of lipids from the intestine is correct?
1. ADietary triacylglycerol must be completely hydrolyzed to free fatty acids and glycerol before absorption.
2. BThe triacylglycerol (TAG) carried by chylomicrons is degraded to free fatty acids and glycerol by lipoprotein lipase on the endothelial surface of capillaries in muscle and adipose primarily.
3. CFatty acids that contain 10 carbons or less are absorbed are absorbed and enter the circulation primarily via the lymphatic system.
4. DDeficiencies in the ability to absorb fat result in excessive amounts of chylomicrons in the blood.
53A fatty acid consists of:
1. Aa hydrophilic hydrocarbon chain and a hydrophobic carboxyl group.
2. Ba hydrophobic hydrocarbon chain and a hydrophobic carboxyl group.
3. Ca hydrophilic hydrocarbon chain and a hydrophilic carboxyl group.
4. Da hydrophobic hydrocarbon chain and a hydrophilic carboxyl group
54Linoleic acid is essential in the diet of humans because of our inability to synthesize it. Linoleic acid may be abbreviated structurally as 18:2(9, 12). Which of the following statements concerning linoleic acid is correct?
1. AIt is 18 carbons long and has 2 double bonds between carbons 9-10 and 12-13.
2. BIt is 18 carbons long and has 3 double bonds between carbons 2-3, 9-10, and 12-13.
3. CIt is 18 carbons long and has 2 double bonds between carbons 8-9 and 11-12.
4. DIt is 18 carbons long and has 3 double bonds between carbons 1-2, 9-10, and 12-13.
55Which of the following correctly describes what would be expected during the synthesis of long chain even numbered saturated fatty acids?
1. AFatty acid synthesis is greatest during starvation.
2. BFatty acid synthesis is enhanced with a high insulin/glucagon ratio
3. CFatty acid synthesis occurs primarily in the mitochondrion.
4. DFatty acid synthesis occurs predominately in muscle and liver.
56Which of the following correctly describes what would be expected during the degradation of long chain even numbered saturated fatty acids?
1. AFatty acid degradation is greatest after a carbohydrate and protein rich meal.
2. BFatty acid degradation is enhanced with a high insulin/glucagon ratio.
3. CFatty acid degradation occurs primarily in the mitochondrion.
4. DFatty acid degradation occurs predominately in kidney and pancreas.
57When fatty acids are required by the body for energy during starvation, which of the following is activated by glucagon or epinephrine and initiates degradation of stored triacylglycerol (TAG) in adipose tissue?
1. AAcetyl CoA carboxylase.
2. BHormone sensitive-lipase
3. CFatty acid synthase.
4. DCarnitine palmitoyl-transferase.
58Unlike fatty acids, ketone bodies are important fuels during fasting and are utilized by the:
1. Alens of the eye
2. Bred blood cells.
3. Cliver.
4. Dbrain.
59A teenager, concerned about his weight, attempts to maintain a fat free diet for a
period of several weeks. If his ability to synthesize various lipids were examined, he
would be found to be most deficient in his ability to synthesize:
1. Atriacylglycerol (TAG).
2. Bphospholipids.
3. Ccholesterol.
4. Dprostaglandins.
60A 6-month old boy was hospitalized following a seizure. History revealed that for
several days prior, his appetite was decreased due to a ‘stomach virus’. At admission,
his blood glucose was 1.30 mmol/L (Age-Referenced Normal Range: 4.0 – 6.0
mmol/L). His urine was negative for ketone bodies, but positive for a variety of
dicarboxylic acids. A tentative diagnosis of medium chain fatty acyl CoA
dehydrogenase (MCAD) deficiency is made. In patients with MCAD deficiency, the
fasting hypoglycemia is a consequence of:
1. Adecreased acetyl CoA production.
2. Bdecreased ability to convert acetyl CoA to glucose.
3. Cincreased conversion of acetyl CoA to acetoacetate.
4. Dincreased production of ATP and NADH.
61Phospholipids:
1. Aare non-polar compounds.
2. Bare composed of an alcohol and either diacylglycerol or sphingosine.
3. Cmay be classified as glycerophospholipids or chylomicrons.
4. Dare hydrophobic compounds.
62The alcohol sphingosine attached to a long chain fatty acid produces:
1. Aphosphorylcholine.
2. Btriacylglycerol.
3. Cdiacylglycerol.
4. Da ceramide.
63Sphingomyelin is degraded to a ceramide and phosphorylcholine by the lysosomal enzyme:
1. Asphingomyelinase.
2. Bin patients with Niemann-Pick (A + B) disease.
3. Cperoxidase.
4. Dbeta-galacatosidase.
64An infant born at 28 weeks of gestation, rapidly gave evidence of respiratory distress.
Lab and X-ray results supported the diagnosis of infant respiratory distress syndrome
(RDS). Which of the following statements best describes this syndrome?
1. AIt is unrelated to the baby’s premature birth.
2. BIt is a consequence of too few Type II pneumocytes.
3. CThe concentration of dipalmytoylphosphatidyl-choline in the amniotic fluid would
  be expected to be lower than that of a full term baby
4. DRDS is an easily treated disorder with low mortality.
65Glycolipids (Glycosphingolipids):
1. Aare synthesized primarily in the mitochondrion.
2. Bare found predominately in brain and nervous tissue cell membranes.
3. Care degraded primarily in the Golgi apparatus by hydrolytic enzymes.
4. Dillicit a very weak immune (Antigenic) response.
66Aspirin-induced asthma (AIA) is a severe reaction to nonsteroidal anti-inflammatory
drugs (NSAIDs) characterized by broncoconstriction 30 mins to several hours after
ingestion. It is seen in as many as 20% of adults. Which of the following statements
best explains the symptoms seen in patients with AIA?
1. ANSAIDs inhibit the activity of the CFTR protein, resulting in thickened secretions
  that block airways.
2. BNSAIDs inhibit COX but not lipoxygenase, resulting in the flow of arachidonic
  acid to leukotriene synthesis.
3. CNSAIDs activate the COX activity of PGH synthase, resulting in increased
  synthesis of prostaglandins that promote vasodilation.
4. DNSAIDs activate phospholipases, resulting in decreased amounts of
  dipalmytoylphosphatidyl-choline.
67Which of the following correctly describes the basis of how low dose aspirin therapy lowers
the risk of stroke and heart attack?
1. AAspirin blocks phospholipid cleavage and breakdown to arachidonic acid by phospholipase
  A2.
2. BAspirin inhibits the conversion of arachidonic acid to 5-HPETE by lipoxygenase.
3. CThe oxidative cyclization of free arachidonic acid by prostaglandin synthase.
4. DCOX-1 inhibition cannot be overcome in platelets but COX-2 inhibition can be overcome in
  endothelial cells.
68Cholesterol:
1. Ais a very hydrophilic compound.
2. Bis synthesized primarily in the mitochondrion.
3. Cis synthesized by virtually all tissues.
4. Dcan be degraded in humans.
69A young girl with a history of severe abdominal pain was taken to her local hospital at 5am in severe distress. Blood was drawn, and the plasma appeared milky, with the triacylglycerol level in excess of 22.60 mmol/L (Normal Reference Range = 0.045 – 1.69 mmol/L). The patient was placed on a diet severely limited in fat but supplemented with medium-chain fatty acids.

Which of the following lipoprotein particles are most likely responsible for the
appearance of the patient’s plasma?
1. AChylomicrons.
2. BVery low density lipoprotein (VLDL).
3. CLow density lipoprotein (LDL).
4. DHigh density lipoprotein (HDL).
70A young girl with a history of severe abdominal pain was taken to her local hospital at 5am in severe distress. Blood was drawn, and the plasma appeared milky, with the triacylglycerol level in excess of 22.60 mmol/L (Normal Reference Range = 0.045 – 1.69 mmol/L). The patient was placed on a diet severely limited in fat but supplemented with medium-chain fatty acids.

Which of the following proteins is most likely to be deficient in this patient?
1. AApo A-1
2. BApo B-48
3. CApo C-II
4. DCholesteryl ester transfer protein
71High density lipoprotein (HDL) functions to:
1. Adeliver cholesterol from peripheral tissues to the liver for elimination
2. Bdeliver cholesterol to the peripheral tissues and the liver.
3. Cdeliver endogenous (Newly synthesized) triacylglycerol (TAG) to peripheral tissues.
4. Ddeliver dietary (Exogenous) triacylglycerol (TAG) to peripheral tissues.
72Chylomicrons function to:
1. Adeliver cholesterol from peripheral tissues to the liver for elimination.
2. Bdeliver cholesterol to the peripheral tissues and the liver.
3. Cdeliver endogenous (Newly synthesized) triacylglycerol (TAG) to peripheral tissues.
4. Ddeliver dietary (Exogenous) triacylglycerol (TAG) to peripheral tissues.
73Low density lipoprotein (LDL) functions to:
1. Adeliver cholesterol to peripheral tissues and the liver.
2. Bdeliver cholesterol from peripheral tissues to the liver for elimination.
3. Cdeliver dietary (Exogenous) triacylglycerol (TAG) to peripheral tissues.
4. Ddeliver endogenous (Newly synthesized) triacylglycerol (TAG) to peripheral tissues.
74Very low density lipoprotein (VLDL) functions to:
1. Adeliver cholesterol from peripheral tissues to the liver for elimination.
2. Bdeliver dietary (Exogenous) triacylglycerol (TAG) to peripheral tissues.
3. Cdeliver endogenous (Newly synthesized) triacylglycerol (TAG) to peripheral tissues.
4. Ddeliver cholesterol to peripheral tissues and the liver.
75Type II hyperlipoproteinemia (Familial hypercholesterolemia) is caused by:
1. Aa deficiency of the enzyme, lipoprotein lipase.
2. Ba deficiency of functional LDL receptors.
3. Cdefective uptake of chylomicron remnants.
4. Da deficiency of the enzyme, acyl CoA:cholesterol acyltransferase (ACAT).
76The most important source of nitrogen entering the body is from:
1. Aurea.
2. Bammonia.
3. Cnucleic acids.
4. Damino acids contained in dietary protein.
77In the transamination reaction catalyzed by aspartate aminotransferase, which of the following are the products, X and Y?
1. AAlanine, alpha-ketoglutarate.
2. BGlutamate, alpha-ketoglutarate.
3. CAspartate, alpha-ketoglutarate.
4. DPyruvate, aspartate.
78Which of the following statements about the urea cycle is CORRECT?
1. AThe two nitrogens that are incorporated into urea enter the cycle as ammonia and
  alanine.
2. BUrea is produced directly by the hydrolysis of ornithine.
3. CATP is required for the reaction in which arginosuccinate is cleaved to form
  arginine.
4. DUrinary urea is increased by a diet rich in protein.
79A female neonate did well until approximately 24 hours of age when she became lethargic. An infection workup proved negative. At 56 hours, she started showing focal seizure activity. The plasma ammonia level was found to be 1,100 mol/L (Normal Reference Interval = 5 – 35 mol/L). Quantitative plasma amino acid levels revealed a marked elevation of arginosuccinate.

Which of the following enzyme activities is most likely to be inhibited in this
patient?
1. AArginase.
2. BArginosuccinate lyase.
3. CArginosuccinate synthetase.
4. DOrnithine transcarbamoylase.
80A female neonate did well until approximately 24 hours of age when she became lethargic. An infection workup proved negative. At 56 hours, she started showing focal seizure activity. The plasma ammonia level was found to be 1,100 mol/L (Normal Reference Interval = 5 – 35 mol/L). Quantitative plasma amino acid levels revealed a marked elevation of arginosuccinate.

Which of the following would also be elevated in the blood of this patient?
1. AAsparagine.
2. BGlutamine.
3. CLysine.
4. DUrea.
81Amino acids whose catabolism yields pyruvate or one of the intermediates of the tricarboxylic
acid cycle are termed:
1. Aketogenic.
2. Bglucogenic.
3. Cessential.
4. Dnonessential.
82Which of the following statements concerning amino acids is correct?
1. AAn increase in gluconeogenesis from amino acids results in a decrease in urea
  formation.
2. BAll essential amino acids are glycogenic.
3. COrnithine and citrulline are found in tissue proteins.
4. DCysteine is an essential amino acid in individuals consuming a diet severely limited
  in methionine.
83Which of the following enzymes is deficient in humans suffering from
phenylketouria (PKU)?
1. ACystathionine synthase.
2. BPhenylalanine hydroxylase.
3. CTyrosinase.
4. DBranched chain alpha-ketoacid dehydrogenase.
84A 1-week old infant, who was born at home in a rural area, has undetected
classic phenylketonuria (PKU). Which statement about this baby and/or her
treatment is correct?
1. ATyrosine is an essential amino acid for the infant.
2. BSupplementation with vitamin B6 is required.
3. CDietary treatment will be recommended to be discontinued in adulthood.
4. DA diet devoid of phenylalanine should be initiated immediately.
85Maple syrup urine disease (MSUD) is an autosomal recessive metabolic disorder in
which there is a partial or complete deficiency in the enzyme:
1. Aphenylalanine hydroxylase.
2. Bbranched chain alpha-keto acid dehydrogenase
3. Ccopper-requiring tyrosinase.
4. Dcystathionine beta-synthase.
86Which of the following statements concerning heme is CORRECT?
1. AHeme synthesis begins with glycine and succinyl CoA.
2. BHeme bound to O2 is composed of Fe 3+.
3. CHeme breakdown occurs in the bone marrow.
4. DCongenital errors of heme metabolism result in phenylketonuria (PKU).
87Which of the following statements correctly describes the catabolism of hemoglobin?
1. AIt occurs in red blood cells.
2. BIt involves the oxidative cleavage of the porphyrin ring
3. CIt results in the liberation of carbon dioxide.
4. DIt is the sole source of bilirubin.
88The porphyrias:
1. Aare generally inherited as autosomal recessive disorders.
2. Bresults in the absence of porphyrins or porphyrin precursors.
3. Care caused by inherited or acquired defects in heme synthesis.
4. Dresults in decreased excretion of porphyrins or porphyrin precursors in the urine.
89delta-aminolevulinate synthase activity:
1. Acatalyzes the rate-limiting reaction in porphyrin biosynthesis.
2. Brequires the coenzyme, biotin.
3. Cis strongly inhibited by heavy metal ions such as lead.
4. Doccurs in the cytoplasm.
90A 50-year old man presented with painful blisters on the backs of his hands. He was
a golf instructor, and indicated that the blisters erupted shortly after the golf season
began. He did not have recent exposure to poison ivy, new soaps or detergents, or
new medications. He denied having previous episodes of previous blistering. He had
partial complex seizure disorder that had begun about 3 years earlier after a head
injury. The patient had been taking phenytoin – his only medication – the onset of
the seizure disorder. He admitted to an average weekly ethanol intake of about 18
cans of beer. The patient’s urine was reddish orange. Cultures obtained from skin
lesions failed to grow organisms. A 24-hour urine collection showed elevated
uroporphyrin (1000 mg; Normal Reference Range < 27 mg). The most likely
diagnosis is:
1. Aporphyria cutanea tarda.
2. Bacute intermittent porphyria.
3. Chereditary coproporphyria.
4. Derythropoietic protoporphyria.

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Description: Quiz on Biochem lecture quizzes compiled, created by Aneesa Sukhai on 24/03/2015.
Author: Aneesa Sukhai
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