Metabolism

1. 1Which of these is not a protease that acts in the small intestine?

   1. AChymotrypsin
   2. BElastase
   3. CEnteropeptidase
   4. DSecretin
   5. ETrypsin 

2. 2Nonessential amino acids:

   1. AAre amino acids other than those required for protein synthesis

   2. BAre not utilised in mammalian proteins.

   3. CAre synthesised by plants and bacteria, but not by humans

   4. DCan be synthesised in humans as well as in bacteria

   5. EMay be substituted with other amino acids in proteins.
3. 3The hormones epinephrine and norepinephrine are derived biosynthetically from:
   

   1. Aarginine

   2. Bhistidine
   3. Cisoleucine
   4. Dtryptophan
   5. Etyrosine
4. 4If a cell were unable to synthesise or obtain tetrahydrofolic acid (H4 folate), it would probably be deficient in the biosynthesis of:
   

   1. Aisoleucine
   2. Bleucine
   3. Clysine
   4. Dmethionine
   5. Eserine.
5. 5Urea synthesis in mammals takes place primarily in tissues of the:
   

   1. Abrain
   2. Bkidney
   3. Cliver

   4. Dskeletal muscle
   5. Esmall intestine.
6. 6Which of these directly donates a nitrogen atom for the formation of urea during the urea cycle?
   

   1. AAdenine
   2. BAspartate
   3. CCreatine
   4. DGlutamate
   5. EOrnithine
7. 7If a person's urine contains unusually high concentrations of urea, which one of the following diets he or she probably been eating recently?
   

   1. AHigh carbohydrate, very low protein

   2. BVery high carbohydrate, no protein, no fat

   3. CVery very high fat, high carbohydrate, no protein
   4. DVery high fat, very low protein
   5. EVery low carbohydrate, very high protein
8. 8In the digestion of protein that occurs in the small intestine, which enzyme is critical in the activation of zymogens? 


   1. AEnteropeptidase
   2. BHexokinase
   3. CPapain
   4. DPepsin
   5. ESecretin 


9. 9Which of the following is a zymogen that can be converted to an endopeptidase that hydrolyzes peptide bonds adjacent to Lys and Arg residues? 



   1. AChymotrypsinogen
   2. BPepsin

   3. CPepsinogen

   4. DTrypsin
   5. ETrypsinogen 

10. 10In amino acid catabolism, the first reaction for many amino acids is a(n): 


    1. Adecarboxylation requiring thiamine pyrophosphate(TPP). 

    2. Bhydroxylation requiring NADPH and O2
    3. Coxidative deamination requiring NAD+
    4. Dreduction requiring pyridoxals phosphate(PLP)
    5. Etransamination requiring pyridoxal phosphate (PLP)

11. 11The coenzyme required for all transaminations is derived from: 


    1. Aniacin
    2. Bpyridoxine (vitamin B6).
    3. Criboflavin
    4. Dthiamin
    5. Evitamin B12. 


12. 12The coenzyme involved in a transaminase reaction is: 


    1. Abiotin phosphate.
    2. Blipoic acid. 

    3. Cnicotinamide adenine dinucleotide phosphate (NADP+). 

    4. Dpyridoxal phosphate(PLP). 

    5. Ethiamine pyrophosphate (TPP). 


13. 13Transamination from alanine to α-ketoglutarate requires the coenzyme: 


    1. Abiotin.
    2. BNADH.
    3. CNo coenzyme is involved.
    4. Dpyridoxal phosphate(PLP).
    5. E
thiamine pyrophosphate (TPP). 


14. 14Pyridoxal phosphate is a cofactor in this class of reactions: 


    1. Aacetylation.
    2. Bdesulfuration
    3. Cmethylation
    4. D
reduction
    5. Etransamination
15. 15Which of the following is not true of the reaction catalyzed by glutamate dehydrogenase? 


    1. AIt is similar to transamination in that it involves the coenzyme pyridoxal phosphate(PLP). 

    2. BNH4+ is produced. 

    3. CThe enzyme can use either NAD+ or NADP+ as a cofactor. 

    4. DThe enzyme is glutamate-specific, but there action is involved in oxidizing other amino acids. 

    5. Eα-Ketoglutarate is produced from an amino acid. 

16. 16Glutamate is metabolically converted to α-ketoglutarate and NH4+ by a process described as: 


    1. Adeamination
    2. Bhydrolysis
    3. Coxidative deamination
    4. Dreductive deamination
    5. Etransamination. 

17. 17The conversion of glutamate to an α-ketoacid and NH4+: 


    1. Adoes not require any cofactors.
    2. Bis a reductive deamination. 

    3. Cis accompanied by ATP hydrolysis catalyzed by the same enzyme. 

    4. Dis catalyzed by glutamate dehydrogenase. 

    5. Erequires ATP . 

18. 18Which of the following conversions require more than one step? 

    1. Alanine → pyruvate

    2. Aspartate → oxaloacetate
    
3. Glutamate → α−ketoglutarate

    4. Phenylalanine → hydroxyphenylpyruvate 

    5. Proline → glutamate 



    1. A1 and 4
    2. B1, 2 , and4
    3. C1 , 3 , and5 

    4. D2 , 4 , and 5
    5. E4 and 5 

19. 19Urea synthesis in mammals takes place primarily in tissues of the: 


    1. Abrain. 

    2. Bkidney.
    3. Cliver. 

    4. Dskeletal muscle.
    5. Esmall intestine. 




20. 20Which substance is not involved in the production of urea from NH4+ via the urea cycle? 


    1. AAspartate
    2. BATP
    3. CCarbamoyl phosphate
    4. DMalate
    5. EOrnithine 

21. 21Which of these directly donates a nitrogen atom for the formation of urea during the urea cycle? 


    1. AAdenine 

    2. BAspartate 

    3. CCreatine
    4. DGlutamate

    5. EOrnithine 

22. 22Conversion of ornithine to citrulline is a step in the synthesis of: 


    1. Aaspartate.
    2. Bcarnitine. 

    3. Cpyruvate. 

    4. Dtyrosine.
    5. Eurea. 

23. 23In the urea cycle, ornithine transcarbamoylase catalyzes: 



    1. Acleavage of urea to ammonia.
    2. Bformation of citrulline from ornithine and another reactant.
    3. Cformation of ornithine from citrulline and another reactant.
    4. Dformation of urea from arginine. 

    5. Etransamination of arginine. 

24. 24Which of the following statements is false in reference to the mammalian synthesis of urea? 


    1. AKrebs was a major contributor to the elucidation of the pathway involved.
    2. BThe amino acid arginine is the immediate precursor to urea. 

    3. CThe carbon atom of urea is derived from mitochondrial HCO3–. 

    4. DThe precursor to one of the nitrogens of urea is aspartate. 

    5. EThe process of urea production is an energy-yielding series of reactions. 

25. 25Which of the following amino acids are essential for humans? 


    1. Aalanine
    2. Baspartic acid
    3. Casparagine
    4. Dserine
    5. Ethreonine 


26. 26Which of these amino acids can be directly converted into a citric acid cycle intermediate by transamination? 


    1. Aglutamic acid
    2. Bserine

    3. Cthreonine

    4. Dtyrosine 

    5. Eproline
27. 27Which of these amino acids are both ketogenic and glucogenic?
    
1. Isoleucine
    
2. Valine

    3. Histidine 

    4. Arginine
    
5. Tyrosine
    

    1. A1 and 5

    2. B1 , 3 , and 5 

    3. C2 and 4

    4. D2 , 3, and 4 

    5. E2 , 4 , and 5 

28. 28Tetrahydrofolate (THF) and its derivatives shuttle .............between different substrates. 


    1. Aelectrons 

    2. BH+
    3. Cacyl groups
    4. Done carbon units
    5. ENH2 groups 



29. 29The amino acids serine, alanine, and cysteine can be catabolized to yield: 


    1. Afumarate. 

    2. Bpyruvate.
    3. Csuccinate. 

    4. Dα-ketoglutarate.
    5. Enone of the above. 

30. 30Serine or cysteine may enter the citric acid cycle as acetyl-CoA after conversion to: 


    1. Aoxaloacetate.
    2. Bpropionate. 

    3. Cpyruvate.

    4. Dsuccinate. 

    5. Esuccinyl-CoA. 

31. 31The human genetic disease phenylketonuria (PKU) can result from: 



    1. Adeficiency of protein in the diet. 

    2. Binability to catabolise ketone bodies. 

    3. Cinability to convert phenylalanine to tyrosine.
    4. Dinability to synthesise phenylalanine.
    5. Eproduction of enzymes containing no phenylalanine. 

32. 32In the human genetic disease maple syrup urine disease, the metabolic defect involves: 



    1. Aa deficiency of the vitamin niacin.
    2. Boxidative decarboxylation. 

    3. Csynthesis of branched chain amino acids.
    4. Dtransamination of an amino acid. 

    5. Euptake of branched chain amino acids into liver. 

33. 33Lipoprotein lipase acts in:
    

    1. Ahydrolysis of triacylglycerols of plasma lipoproteins to supply fatty acids to various tissues.
    2. Bintestinal uptake of dietary fat.
    3. Cintracellular lipid breakdown of lipoproteins.
    4. Dlipoprotein breakdown to supply needed amino acids.
    5. Enone of the above.
34. 34Lipoprotein lipase acts in:

    1. Ahydrolysis of triacylglycerols of plasma lipoproteins to supply fatty acids to various tissues.
    2. Bintestinal uptake of dietary fat.
    3. Cintracellular lipid breakdown of lipoproteins.
    4. Dlipoprotein breakdown to supply needed amino acids.
    5. Enone of the above.
35. 35Free fatty acids in the bloodstream are:
    

    1. Abound to hemoglobin.
    2. Bcarried by the protein serum albumin.
    3. Cfreely soluble in the aqueous phase of the blood.
    4. Dnonexistent; the blood does not contain free fatty acids.
    5. Epresent at levels that are independent of epinephrine.
36. 36The role of hormone-sensitive triacylglycerol lipase is to:
    

    1. Ahydrolyse lipids stored in the liver.
    2. Bhydrolyse membrane phospholipids in hormone-producing cells.
    3. Chydrolyse triacylglycerols stored in adipose tissue.
    4. Dsynthesise lipids in adipose tissue.
    5. Esynthesise triacylglycerols in the liver.
37. 37 The glycerol produced from the hydrolysis of triacylglycerides enters glycolysis as:
    
    

    1. Aglucose.
    2. Bglucose-6-phosphate.
    3. Cdihydroxyacetone phosphate.
    4. Dpyruvate.
    5. Eglyceryl CoA.
38. 38Transport of fatty acids from the cytoplasm to the mitochondrial matrix requires:
    

    1. AATP, carnitine, and coenzyme A.
    2. BATP, carnitine, and pyruvate dehydrogenase.
    3. CATP, coenzyme A, and hexokinase.
    4. DATP, coenzyme A, and pyruvate dehydrogenase.
    5. Ecarnitine, coenzyme A, and hexokinase.
39. 39Fatty acids are activated to acyl-CoAs and the acyl group is further transferred to carnitine because:
    

    1. Aacyl-carnitines readily cross the mitochondrial inner membrane, but acyl-CoAs do not.
    2. Bacyl-CoAs easily cross the mitochondrial membrane, but the fatty acids themselves will not.
    3. Ccarnitine is required to oxidize NAD+ to NADH.
    4. Dfatty acids cannot be oxidized by FAD unless they are in the acyl-carnitine form.
    5. ENone of the above is true.
40. 40Carnitine is:

    1. Aa 15-carbon fatty acid.
    2. Ban essential cofactor for the citric acid cycle.
    3. Cessential for intracellular transport of fatty acids.
    4. Done of the amino acids commonly found in protein.
    5. Epresent only in carnivorous animals.
41. 41Which of these is able to cross the inner mitochondrial membrane?
    

    1. AAcetyl–CoA
    2. BFatty acyl–carnitine
    3. CFatty acyl–CoA
    4. DMalonyl–CoA
    5. ENone of the above can cross.
42. 42What is the correct order of function of the following enzymes of B-oxidation?
    1. B-Hydroxyacyl-CoA dehydrogenase
    2. Thiolase
    3. Enoyl-CoA hydratase
    4. Acyl-CoA dehydrogenase 


    1. A1, 2, 3, 4
    2. B3, 1, 4, 2
    3. C4, 3, 1, 2
    4. D1, 4, 3, 2
    5. E4, 2, 3, 1
43. 43If the 16-carbon saturated fatty acid palmitate is oxidized completely to carbon dioxide and water (via the B-oxidation pathway and the citric acid cycle), and all of the energy-conserving products are used to drive ATP synthesis in the mitochondrion, the net yield of ATP per molecule of palmitate is: 


    1. A3
    2. B10
    3. C25
    4. D108
    5. E1000
44. 44Saturated fatty acids are degraded by the stepwise reactions of B-oxidation, producing acetyl-CoA. Under aerobic conditions, how many ATP molecules would be produced as a consequence of removal of each acetyl-CoA?


    1. A2
    2. B3
    3. C4
    4. D5
    5. E6
45. 45Which of the following is (are) true of the oxidation of 1 mol of palmitate (a 16-carbon saturated fatty acid; 16:0) by the B-oxidation pathway, beginning with the free fatty acid in the cytoplasm?

    1. Activation of the free fatty acid requires the equivalent of two ATPs.
    2. Inorganic pyrophosphate (PPi) is produced.
    3. Carnitine functions as an electron acceptor.
    4. 8 mol of FADH2 are formed.
    5. 8 mol of acetyl-CoA are formed.
    6. There is no direct involvement of NAD+. 


    1. A1 and 5 only
    2. B1, 2, and 5
    3. C1, 2, and 6
    4. D1, 3, and 5
    5. E5 only
46. 46Complete oxidation of 1 mole of which fatty acid would yield the most ATP?


    1. A16-carbon saturated fatty acid
    2. B18-carbon mono-unsaturated fatty acid
    3. C16-carbon mono-unsaturated fatty acid
    4. D16-carbon poly-unsaturated fatty acid
    5. E14-carbon saturated fatty acid
47. 47Which of the following statements apply (applies) to the B-oxidation of fatty acids?

    1. The process takes place in the cytosol of mammalian cells.
    2. Carbon atoms are removed from the acyl chain one at a time.
    3. Before oxidation, fatty acids must be converted to their CoA derivatives.
    4. NADP+ is the electron acceptor.
    5. The products of B-oxidation can directly enter the citric acid cycle for further oxidation.

    1. A1 and 3 only
    2. B1, 2, and 3
    3. C1, 2, and 5
    4. D3 and 5 only
    5. E4 only
48. 48Which of the following statements concerning the B-oxidation of fatty acids is true? 


    1. AAbout 1,200 ATP molecules are ultimately produced per 20-carbon fatty acid oxidized.
    2. BOne FADH2 and two NADH are produced for each acetyl-CoA.
    3. CThe free fatty acid must be carboxylated in the B-position by a biotin-dependent reaction before the process of B-oxidation commences.
    4. DThe free fatty acid must be converted to a thioester before the process of B-oxidation commences.
    5. ETwo NADH are produced for each acetyl-CoA.
49. 49The balanced equation for the degradation of CH3(CH2)10COOH via the B-oxidation pathway is:
    

    1. ACH3(CH2)10COOH + 5FAD + 5NAD+ + 6CoA—SH + 5H2O + ATP -->
       6 Acetyl-CoA + 5FADH2 + 5NADH + 5H+ + AMP + PPi
    2. BCH3(CH2)10COOH + 5FAD + 5NAD+ + 6CoA—SH + 5H2O -->
       6 Acetyl-CoA + 5FADH2 + 5NADH + 5H+
    3. CCH3(CH2)10COOH + 6FAD + 6NAD+ + 6CoA—SH + 6H2O + ATP -->
       6 Acetyl-CoA + 6FADH2 + 6NADH + 6H+ + AMP + PPi
    4. DCH3(CH2)10COOH + 6FAD + 6NAD+ + 6CoA—SH + 6H2O -->
       6 Acetyl-CoA + 6FADH2 + 6NADH + 6H+
50. 50Which compound is an intermediate of the B-oxidation of fatty acids?


    1. ACH3—(CH2)20—CO—COOH
    2. BCH3—CH2—CO—CH2—CO—OPO32–
    3. CCH3—CH2—CO—CH2—OH
    4. DCH3—CH2—CO—CO—S—CoA
    5. ECH3—CO—CH2—CO—S—CoA
51. 51The conversion of palmitoyl-CoA (16:0) to myristoyl-CoA (14:0) and 1 mol of acetyl-CoA by the B-oxidation pathway results in the net formation of: 


    1. A1 FADH2 and 1 NADH.
    2. B1 FADH2 and 1 NADPH.
    3. C1 FADH2, 1 NADH, and 1 ATP.
    4. D2 FADH2 and 2 NADH.
    5. E2 FADH2, 2 NADH, and 1 ATP.
52. 52Which of the following is not true regarding the oxidation of 1 mol of palmitate (16:0) by the B-oxidation pathway? 


    1. A1 mol of ATP is needed.
    2. B8 mol of acetyl-CoA are formed.
    3. C8 mol of FADH2 are formed.
    4. DAMP and PPi are formed.
    5. EThe reactions occur in the mitochondria.
53. 53If an aerobic organism (e.g., the bacterium E. coli) were fed each of the following four compounds as a source of energy, the energy yield per mole from these molecules would be in the order:

    1. Aalanine > glucose > palmitate (16:0)
    2. Bglucose > alanine > palmitate
    3. Cglucose > palmitate > alanine
    4. Dpalmitate > alanine > glucose
    5. Epalmitate > glucose > alanine
54. 54Which of the following is (are) true of the B-oxidation of long-chain fatty acids?
    
    1. The enzyme complex that catalyzes the reaction contains biotin.
    2. FADH2 serves as an electron carrier.
    3. NADH serves as an electron carrier.
    4. Oxidation of an 18-carbon fatty acid produces six molecules of propionyl-CoA.
    5. Oxidation of a 15-carbon fatty acid produces at least one propionyl-CoA. 


    1. A1, 2, and 3
    2. B1, 2, and 5
    3. C2, 3, and 4
    4. D2, 3, and 5
    5. E3 and 5 only
55. 55The following fatty acid, in which the indicated carbon is labeled with 14C, is fed to 
an animal: 14CH3(CH2)9COOH
    
    After allowing 30 minutes for fatty acid B-
 oxidation, the label would most likely be recovered in: 


    1. Aacetyl-CoA.
    2. Bbeta-hydroxy butyryl-CoA.
    3. Cboth acetyl-CoA and propionyl-CoA.
    4. Dpalmitoyl-CoA.
    5. Epropionyl-CoA.
56. 56The carbon atoms from a fatty acid with an odd number of carbons will enter the citric acid cycle as acetyl-CoA and: 


    1. Abutyrate.
       
       

    2. Bcitrate.
    3. Cmalate.
    4. Dsuccinyl-CoA.
    5. Ea-ketoglutarate.
57. 57In the disease sprue, vitamin B12 (cobalamin) is poorly absorbed in the intestine, resulting in B12 deficiency. If each of the following fatty acids were in the diet, for which one would the process of fatty acid oxidation be most affected in a patient with sprue?

    1. Apyruvate carboxylase
    2. Bcarnitine acyl transferase I
    3. Cacetyl CoA dehydrogenase
    4. Denoyl CoA isomerase
    5. Emethylmalonyl CoA mutase
58. 58During B-oxidation of fatty acids, _____is produced in peroxisomes but not in mito


    1. Aacetyl-CoA
    2. BFADH2
    3. CH2O
    4. DH2O2
    5. ENADH
59. 59Ketone bodies are formed in the liver and transported to the extrahepatic tissues mainly as:


    1. Aacetoacetyl-CoA.
    2. Bacetone.
    3. Cbeta-hydroxybutyric acid.
    4. Dbeta-hydroxybutyryl-CoA.
    5. Elactic acid.
60. 60The major site of formation of acetoacetate from fatty acids is the:
    

    1. Aadipose tissue.
    2. Bintestinal mucosa.
    3. Ckidney.
    4. Dliver.
    5. Emuscle.
61. 61Lipoprotein lipase acts in:

    1. Ahydrolysis of triacylglycerols of plasma lipoproteins to supply fatty acids to various tissues.
    2. Bintestinal uptake of dietary fat.
    3. C intracellular lipid breakdown of lipoproteins.
    4. Dlipoprotein breakdown to supply needed amino acids.
    5. Enone of the above.
62. 62Free fatty acids in the bloodstream are:
    

    1. Abound to hemoglobin.
    2. Bcarried by the protein serum albumin.
    3. Cfreely soluble in the aqueous phase of the blood.
    4. Dnonexistent; the blood does not contain free fatty acids.
    5. Epresent at levels that are independent of epinephrine.
63. 63The role of hormone-sensitive triacylglycerol lipase is to:

    1. A hydrolyze lipids stored in the liver.
    2. Bhydrolyze membrane phospholipids in hormone-producing cells. 

    3. Chydrolyze triacylglycerols stored in adipose tissue. 

    4. D synthesize lipids in adipose tissue. 

    5. Esynthesize triacylglycerols in the liver. 

64. 64Which enzyme is the major regulatory control point for β-oxidation? 


    1. A pyruvate carboxylase 

    2. B carnitine acyl transferase I 

    3. Cacetyl CoA dehydrogenase 

    4. D enoyl CoA isomerase 

    5. Emethylmalonyl CoA mutase 

65. 65During β oxidation of fatty acids, ___________ is produced in peroxisomes but not in mitochondria. 


    1. Aacetyl-CoA 

    2. BFADH2 

    3. CH2O 

    4. DH2O2 

    5. ENADH 

66. 66When comparing the β-oxidation and ω-oxidation pathways, which one of the following statements is correct?

    1. A β-oxidation and ω-oxidation occur in the cytoplasm. 

    2. B β oxidation occurs at the carboxyl end of the fatty acid whereas ω oxidation occurs at the methyl 
end. 

    3. Cβ oxidation occurs at the methyl end of the fatty acid whereas ω oxidation occurs at the carboxyl 
end. 

    4. D β oxidation occurs mainly in the cytoplasm whereas ω oxidation occurs mainly in the 
mitochondria. 

    5. Eβ oxidation occurs mainly in the mitochondria whereas ω oxidation occurs mainly in the 
cytoplasm. 

67. 67Ketone bodies are formed in the liver and transported to the extrahepatic tissues mainly as: 


    1. Aacetoacetyl-CoA. 

    2. Bacetone.
    3. Cbeta-hydroxybutyric acid. 

    4. Dbeta-hydroxybutyryl-CoA. 

    5. Elactic acid. 

68. 68The major site of formation of acetoacetate from fatty acids is the: 


    1. Aadipose tissue. 

    2. Bintestinal mucosa. 

    3. C kidney. 

    4. Dliver. 

    5. Emuscle. 

69. 69The radioimmunossay (RIA) is based on competition of unlabeled and radiolabeled:

    1. Aantibodies for binding to a hormone.
    2. Bantibodies for binding to a receptor.
    3. Chormone for binding to a receptor
    4. Dhormone for binding to an antibody
    5. Ereceptor for binding to a hormone
70. 70One distinction between peptide and steroid hormones is that peptide hormones:

    1. AAct through nonspecific receptors, whereas steroid hormones act through specific receptors.
    2. Bare generally water-insoluble, whereas steroid hormones are water soluble.
    3. Care more stable than steroid hormones.
    4. Dbind to cell surface receptors, whereas steroid hormones bind to nuclear receptors.
    5. Ebind to their receptors with high affinity, whereas steroid hormones bind with low affinity.
71. 71The maturation of insulin from its precursor (preproinsulin) involves:

    1. Aacetylation
    2. Boxidation
    3. Cphosphorylation
    4. Dproteolysis
    5. Ereduction
72. 72Epinephrine is an example of a(n) ____________ hormone.

    1. Acatecholamine
    2. Beicosanoid
    3. Cparacrine
    4. Dpeptide
    5. Esteroid
73. 73An example of an eicosanoid hormone is:

    1. Aepinephrine
    2. Bretinoic aicd
    3. Ctestosterone
    4. Dthromboxane
    5. Ethyroxine
74. 74An example of a steroid hormone is:

    1. Aepinephrine
    2. Bretinoic acid
    3. Ctestosterone
    4. Dthromboxane
    5. Ethyroxine
75. 75Some hormones are derived from amino acids; for example, catecholamines are derived from while NO is derived from .

    1. Atyrosine; arginine
    2. Btryptophan; lysine
    3. Ctyrosine; histidine
    4. Dtryptophan; arginine
    5. Ehistidine; lysine
76. 76The tropic hormones (such as thyrotropin, somatotropin, and luteinizing hormone) are produced and released by the:

    1. Aanterior pituitary
    2. Bhypothalamus
    3. Covaries
    4. Dpancreas
    5. Eposterior pituitary
77. 77The normal sequence of action of these components of the hormonal hierarchy is:

    1. Aadrenal cortex --> hypothalamus --> anterior pituitary
    2. Banterior pituitary --> adrenal cortex --> hypothalamus
    3. Canterior pituitary --> hypothalamus --> adrenal cortex
    4. Dhypothalamus --> adrenal cortex --> anterior pituitary
    5. Ehypothalamus --> anterior pituitary --> adrenal cortex
78. 78In its role in the hormonal hierarchy, the hypothalamus produces and releases:

    1. Aepinephrine
    2. Binsulin
    3. Cprogesterone
    4. Dreleasing factors
    5. Ethyroxine
79. 79Which of the following statements about metabolism in the mammalian liver is false?

    1. AMost plasma lipoproteins are synthesized in the liver.
    2. BThe enzymatic complement of liver tissue changes in response to changes in the diet.
    3. CThe liver synthesizes most of the urea produced in the body.
    4. DThe presence of glucose 6-phosphatase makes liver uniquely able to release glucose into the bloodstream.
    5. EUnder certain conditions, most of the functions of the liver can be performed by other organs.
80. 80Glucokinase:

    1. Aacts in the conversion of liver glycogen to glucose 1-phosphate
    2. Bconverts fructose-6-phosphate to glucose-6-phosphate
    3. Cconverts glucose 6-phosphate to fructose 6-phosphate.
    4. Dis a hexokinase isozyme found in liver hepatocytes.
    5. Eis found in all mammalian tissues.
81. 81In skeletal muscle

    1. Aamino acids are an essential fuel.
    2. Bat rest, fatty acids are the preferred fuel.
    3. Clarge quantities of triacylglycerol are stored as fuel.
    4. Dphosphocreatine can substitute for ATP as the direct source of energy for muscle contraction.
    5. Estored muscle glycogen can be converted to glucose and released to replenish blood glucose.
82. 82In skeletal muscle, phosphocreatine functions as:

    1. Aa reservoir of Pi for mitochondria
    2. Breservoir of high-energy of phosphate to replenish ATP.
    3. Creservoir of amino acids for protein synthesis.
    4. Dan electron acceptor under anaerobic conditions.
    5. Enone of the above.
83. 83The Cori cycle is:

    1. Athe conversion of lactate to pyruvate in skeletal muscle to drive glycogen synthesis.
    2. Bthe interconversion between glycogen and glucose l-phosphate.
    3. Cthe production of lactate from glucose in peripheral tissues with the resynthesis of glucose from lactate in liver.
    4. Dthe synthesis of alanine from pyruvate in skeletal muscle and the synthesis of pyruvate from alanine in liver.
    5. Ethe synthesis of urea in liver and degradation of urea to carbon dioxide and ammonia by bacteria in the gut
84. 84Which one of the following statements is true?

    1. AThe brain prefers glucose as an energy source, but can use ketone bodies.
    2. BMuscle cannot use fatty acids as an energy source.
    3. CIn a well-fed human, about equal amounts of energy are stored as glycogen and as triacylglycerol.
    4. DFatty acids cannot be used as an energy source in humans because humans lack the enzymes of the glyoxylate cycle.
    5. EAmino acids are a preferable energy source over fatty acids.
85. 85When blood glucose is abnormally high, the pancreas releases:

    1. Aepinephrine
    2. Bglucagon
    3. Cglucose
    4. Dinsulin
    5. Etrypsin
86. 86When blood glucose is abnormally low, the pancreas releases:

    1. Aepinephrine
    2. Bglucagon
    3. Cglucose
    4. Dinsulin
    5. Etrypsin
87. 87An elevated insulin level in the blood:

    1. Ainhibits glucose uptake by the liver
    2. Binhibits glycogen synthesis in the liver and muscle.
    3. Cresults from a below-normal blood glucose level.
    4. Dstimulates glycogen breakdown in liver.
    5. Estimulates synthesis of fatty acids and triacylglycerols in the liver.
88. 88The largest energy store in a well-nourished human is:

    1. AATP in all tissues
    2. Bblood glucose
    3. Cliver glycogen
    4. Dmuscle glycogen
    5. Etriacylglycerols in adipose tissues
89. 89Elevated epinephrine levels do not normally stimulate:

    1. Afatty acid mobilization in adipose tissue.
    2. Bgluconeogenesis in liver.
    3. Cglycogen breakdown in muscle.
    4. Dglycogen synthesis in liver.
    5. Eglycolysis in muscle.
90. 90Epinephrine triggers an increased rate of glycolysis in muscle by:

    1. Aactivation of hexokinase.
    2. Bactivation of phosphofructokinase-1.
    3. Cconversion of glycogen phosphorylase a to glycogen phosphorylase b.
    4. Dinhibition of the Cori Cycle
    5. Ethe Pasteur effect.
91. 91Long-term maintenance of body weight is regulated by the hormone:

    1. Aadiposin
    2. Bhypothalmin
    3. Cleptin
    4. Dobesin
    5. Etestosterone
92. 92Among its numerous metabolic effects, the protein leptin:

    1. Adecreases the production of glucocorticoids.
    2. Binactivates the enzyme 5’-AMP-activated protein kinase (AMPK).
    3. Cincreases the production of sex hormones.
    4. Dmakes muscle and liver cells more sensitive to insulin.
    5. Eraises the production of thyroid hormone.
93. 93The hormone leptin........ appetite; insulin ........ appetite.

    1. Aincreases; increases
    2. Bincreases; decreases
    3. Cdecreases; increases
    4. Ddecreases; decreases
    5. Eno effect; no effect
94. 94The peptide hormone adiponectin, produced in adipose tissue, circulates in the blood and:

    1. Aenhances fatty acid synthesis in liver cells.
    2. Bincreases the rate of b-oxidation of fatty acids in muscle cells.
    3. Cinhibits glucose uptake and catabolism in muscle and liver cells.
    4. Dreduces the transport of fatty acids into muscle cells.
    5. Estimulates gluconeogenesis in liver cells.
95. 95Glycolysis is the name given to a metabolic pathway occurring in many different cell types. It consists of 11 enzymatic steps that convert glucose to lactic acid. Glycolysis is an example of:

    1. Aaerobic metabolism
    2. Banabolic metabolism
    3. Ca net reductive process
    4. Dfermentation
    5. Eoxidative phosphorylation
96. 96The anaerobic conversion of 1 mol of glucose to 2 mol of lactate by fermentation is accompanied by a net gain of:

    1. A1 mol of ATP
    2. B1 mol of NADH
    3. C2 mol of ATP
    4. D2 mol of NADH
    5. Enone of the above
97. 97During strenuous exercise, the NADH formed in the glyceraldehyde 3-phosphate dehydrogenase reaction in skeletal muscle must be reoxidized to NAD+ if glycolysis is to continue. The most important reaction involved in the reoxidation of NADH is:

    1. Adihydroxyacetone phosphate → glycerol 3-phosphate
    2. Bglucose 6-phosphate → fructose 6-phosphate
    3. Cisocitrate → α-ketoglutarate
    4. Doxaloacetate → malate
    5. Epyruvate → lactate
98. 98If glucose labeled with 14C in C-1 were fed to yeast carrying out the ethanol fermentation, where would the 14C label be in the products?

    1. AInC-1ofethanolandCO2
    2. BIn C-1 of ethanol only
    3. CIn C-2 (methyl group) of ethanol only
    4. DInC-2ofethanolandCO2
    5. EIn CO2 only
99. 99The conversion of 1 mol of fructose 1,6-bisphosphate to 2 mol of pyruvate by the glycolytic pathway results in a net formation of:

    1. A1mol of NAD+ and 2 mol of ATP.
    2. B1mol of NADH and 1 mol of ATP.
    3. C2mol of NAD+ and 4 mol of ATP.
    4. D2mol of NADH and 2 mol of ATP.
    5. E2mol of NADH and 4 mol of ATP.
100. 100In an anaerobic muscle preparation, lactate formed from glucose labeled in C-3 and C-4 would be labeled in:

     1. Aall three carbon atoms.
     2. Bonly the carbon atom carrying the OH.
     3. Conly the carboxyl carbon atom.
     4. Donly the methyl carbon atom.
     5. Ethe methyl and carboxyl carbon atoms.
101. 101Which of the following statements is not true concerning glycolysis in anaerobic muscle?

     1. AFructose1,6-bisphosphatase is one of the enzymes of thepathway.
     2. BIt is an endergonic process.
     3. CIt results in net synthesis of A TP .
     4. DIt results in synthesis of NADH.
     5. EIts rate is slowed by a high [ATP]/[ADP] ratio.
102. 102When a muscle is stimulated to contract aerobically, less lactic acid is formed than when it contracts anaerobically because:

     1. Aglycolysis does not occur to significant extent under aerobic conditions.
     2. Bmuscle is metabolically less active under aerobic than anaerobic conditions.
     3. Cthe lactic acid generated is rapidly incorporated into lipids under aerobic conditions.
     4. Dunder aerobic conditions in muscle, the major energy-yielding pathway is the pentose phosphate pathway, which does not produce lactate.
     5. Eunder aerobic conditions most of the pyruvate generated as a result of glycolysis is oxidized by the citric acid cycle rather than reduced to lactate.
103. 103Glycolysis in the erythrocyte produces pyruvate that is further metabolized to:

     1. ACO2
     2. Bethanol
     3. Cglucose
     4. Dhemoglobin
     5. Elactate
104. 104When a mixture of glucose 6-phosphate and fructose 6-phosphate is incubated with the enzyme phosphohexose isomerase, the final mixture contains twice as much glucose 6-phosphate as fructose 6-phosphate. Which one of the following statements is most nearly correct, when applied to the reaction below (R = 8.315 J/mol·K and T = 298 K)?
     
     Glucose 6-phosphate ↔ fructose 6-phosphate

     1. AΔG'°is+1.7kJ/mol.
     2. BΔG'° is –1.7 kJ/mol.
     3. CΔG'° is incalculably large and negative.
     4. DΔG'°isincalculablylargeandpositive.
     5. EΔG'° is zero.
105. 105In glycolysis, fructose 1,6-bisphosphate is converted to two products with a standard free-energy change (G'°) of 23.8 kJ/mol. Under what conditions (encountered in a normal cell) will the free-energy change (G) be negative, enabling the reaction to proceed to the right?

     1. AIf the concentrations of the two products are high relative to that of fructose 1,6-bisphosphate.
     2. BThe reaction will not go to the right spontaneously under any conditions because the G'° is positive.
     3. CUnder standard conditions, enough energy is released to drive the reaction to the right.
     4. DWhen there is a high concentration of fructose 1,6-bisphosphate relative to the concentration of products.
     5. EWhen there is a high concentration of products relative to the concentration of fructose 1,6-bisphosphate.
106. 106Glucose labeled with 14C in C-1 and C-6 gives rise in glycolysis to pyruvate labeled in:

     1. AA and C
     2. Ball three carbons.
     3. Cits carbonyl carbon
     4. Dits carboxyl carbon
     5. Eits methyl carbon
107. 107If glucose labeled with 14C at C-1 (the aldehyde carbon) were metabolized in the liver, the first radioactive pyruvate formed would be labeled in:

     1. Aall three carbons
     2. Bboth a and c
     3. Cits carbonyl carbon
     4. Dits carboxyl carbon
     5. Eits methyl carbon
108. 108If glucose labeled with 14C in C-3 is metabolized to lactate via fermentation, the lactate will contain 14C in:

     1. Aall three carbon atoms.
     2. Bonly the carbon atom carrying the OH.
     3. Conly the carboxyl carbon atom.
     4. Donly the methyl carbon atom.
     5. Ethe methyl and carboxyl carbon atoms
109. 109Which of these cofactors participates directly in most of the oxidation-reduction reactions in the fermentation of glucose to lactate?

     1. AADP
     2. BATP
     3. CFAD/FADH2
     4. DGlyceraldehyde 3-phosphate
     5. ENAD+/NADH
110. 110In comparison with the resting state, actively contracting human muscle tissue has a:

     1. Ahigher concentration of ATP.
     2. Bhigher rate of lactate formation.
     3. Clower consumption of glucose.
     4. Dlower rate of consumption of oxygen
     5. Elower ratio of NADH to NAD+.
111. 111The steps of glycolysis between glyceraldehyde 3-phosphate and 3-phosphoglycerate involve all of the following except:

     1. AATP synthesis
     2. Bcatalysis by phosphoglycerate kinase.
     3. Coxidation of NADH to NAD+.
     4. Dthe formation of 1,3-bisphosphoglycerate.
     5. Eutilization of Pi
112. 112The first reaction in glycolysis that results in the formation of an energy-rich compound (i.e., a compound whose hydrolysis has a highly negative G'°) is catalyzed by:

     1. Aglyceraldehyde 3-phosphate dehydrogenase.
     2. Bhexokinase.
     3. Cphosphofructokinase-1.
     4. Dphosphoglycerate kinase.
     5. Etriose phosphate isomerase.
113. 113Which of the following is a cofactor in the reaction catalyzed by glyceraldehyde 3-phosphate dehydrogenase?

     1. AATP
     2. BCU2+
     3. Cheme
     4. DNAD+
     5. ENADP+
114. 114In the phosphoglycerate mutase reaction, the side chain of which amino acid in the enzyme is transiently phosphorylated as part of the reaction?

     1. Aserine
     2. Bthreonine
     3. Ctyrosine
     4. Dhistidine
     5. Earginine
115. 115Inorganic fluoride inhibits enolase. In an anaerobic system that is metabolizing glucose as a substrate, which of the following compounds would you expect to increase in concentration following the addition of fluoride?

     1. A2-phosphoglycerate
     2. Bglucose
     3. Cglyoxylate
     4. DPhosphoenolpyruvate
     5. Epryruvate
116. 116Glycogen is converted to monosaccharide units by:

     1. Aglucokinase
     2. Bglucose-6-phosphatase
     3. Cglycogen phosphorylase
     4. Dglycogen synthase
     5. Eglycogenase
117. 117Galactosemia is a genetic error of metabolism associated with:

     1. Adeficiency of galactokinase.
     2. Bdeficiency of UDP-glucose.
     3. Cdeficiency of UDP-glucose: galactose 1-phosphate uridylyltransferase.
     4. Dexcessive ingestion of galactose.
     5. Einability to digest lactose.
118. 118Which of the following statements is incorrect?

     1. AAerobically, oxidative decarboxylation of pyruvate forms acetate that enters the citric acid cycle.
     2. BIn anaerobic muscle, pyruvate is converted to lactate.
     3. CIn yeast growing anaerobically, pyruvate is converted to ethanol.
     4. DReduction of pyruvate to lactate regenerates a cofactor essential for glycolysis.
     5. EUnder anaerobic conditions pyruvate does not form because glycolysis does not occur.
119. 119The ultimate electron acceptor in the fermentation of glucose to ethanol is:

     1. Aacetaldehyde
     2. Bacetate
     3. Cethanol
     4. DNAD+
     5. Epyruvate
120. 120In the alcoholic fermentation of glucose by yeast, thiamine pyrophosphate is a coenzyme required by:

     1. Aaldolase
     2. Bhexokinase
     3. Clactate dehydrogenase
     4. Dpyruvate decarboxylase
     5. Etransaldolase
121. 121Which of the following compounds cannot serve as the starting material for the synthesis of glucose via gluconeogenesis?

     1. Aacetate
     2. Bglycerol
     3. Clactate
     4. Doxaloacetate
     5. Ea-ketoglutarate
122. 122An enzyme used in both glycolysis and gluconeogenesis is:

     1. A3-phosphoglycerate kinase.
     2. Bglucose 6-phosphatase.
     3. Chexokinase.
     4. Dphosphofructokinase-1.
     5. Epyruvate kinase.
123. 123Which one of the following statements about gluconeogenesis is false?

     1. AFor starting materials, it can use carbon skeletons derived from certain amino acids.
     2. BIt consists entirely of the reactions of glycolysis, operating in the reverse direction.
     3. CIt employs the enzyme glucose 6-phosphatase.
     4. DIt is one of the ways that mammals maintain normal blood glucose levels between meals.
     5. EIt requires metabolic energy (ATP or GTP).
124. 124All of the following enzymes involved in the flow of carbon from glucose to lactate (glycolysis) are also involved in the reversal of this flow (gluconeogenesis) except:

     1. A3-phosphoglycerate kinase.
     2. Baldolase.
     3. Cenolase.
     4. Dphosphofructokinase-1.
     5. Ephosphoglucoisomerase.
125. 125Which of the following substrates cannot contribute to net gluconeogenesis in mammalian liver?

     1. Aalanine
     2. Bglutamate
     3. Cpalmitate
     4. Dpyruvate
     5. Ea-ketoglutarate
126. 126Which of the following statements about the pentose phosphate pathway is correct?

     1. AIt generates 36 mol of ATP per mole of glucose consumed.
     2. BIt generates 6 moles of CO2 for each mole of glucose consumed
     3. CIt is a reductive pathway; it consumes NADH.
     4. DIt is present in plants, but not in animals.
     5. EIt provides precursors for the synthesis of nucleotides.
127. 127The main function of the pentose phosphate pathway is to:

     1. Agive the cell an alternative pathway should glycolysis fail.
     2. Bprovide a mechanism for the utilization of the carbon skeletons of excess amino acids.
     3. Csupply energy.
     4. Dsupply NADH.
     5. Esupply pentoses and NADPH.
128. 128The metabolic function of the pentose phosphate pathway is:

     1. Aact as a source of ADP biosynthesis.
     2. Bgenerate NADPH and pentoses for the biosynthesis of fatty acids and nucleic acids.
     3. Cparticipate in oxidation-reduction reactions during the formation of H2O.
     4. Dprovide intermediates for the citric acid cycle.
     5. Esynthesize phosphorus pentoxide.
129. 129Which of the following statements about the pentose phosphate pathway is incorrect?

     1. AIt generates CO2 from C-1 of glucose.
     2. BIt involves the conversion of an aldohexose to an aldopentose.
     3. CIt is prominant in lactating mammary gland.
     4. DIt is principally directed toward the generation of NADPH.
     5. EIt requires the participation of molecular oxygen.
130. 130Glucose breakdown in certain mammalian and bacterial cells can occur by mechanisms other than classic glycolysis. In most of these, glucose 6-phosphate is oxidized to 6-phosphogluconate, which is then further metabolized by:

     1. Aan aldolase-type split to form glyceric acid and glyceraldehyde 3-phosphate.
     2. Ban aldolase-type split to form glycolic acid and erythrose 4-phosphate.
     3. Cconversion to 1,6-bisphosphogluconate.
     4. Ddecarboxylation to produce keto- and aldopentoses.
     5. Eoxidation to a six-carbon dicarboxylic acid.
131. 131Which of the following enzymes acts in the pentose phosphate pathway?

     1. A6-phosphogluconate dehydrogenase
     2. Baldolase
     3. CGlycogen phosphorylase
     4. DPhosphofructokinase-1
     5. EPyruvate kinase
132. 132The oxidation of 3 mol of glucose by the pentose phosphate pathway may result in the production of:

     1. A2 mol of pentose, 4 mol of NADPH, and 8 mol of CO2.
     2. B3 mol of pentose, 4 mol of NADPH, and 3 mol of CO2.
     3. C3 mol of pentose, 6 mol of NADPH, and 3 mol of CO2.
     4. D4 mol of pentose, 3 mol of NADPH, and 3 mol of CO2.
     5. E4 mol of pentose, 6 mol of NADPH, and 6 mol of CO2.
133. 133Glucose, labeled with 14C in different carbon atoms, is added to a crude extract of a tissue rich in the enzymes of the pentose phosphate pathway. The most rapid production of 14CO2 will occur when the glucose is labeled in:

     1. AC-1
     2. BC-3
     3. CC-4
     4. DC-5
     5. EC-6
134. 134In a tissue that metabolizes glucose via the pentose phosphate pathway, C-1 of glucose would be expected to end up principally in:

     1. Acarbon dioxide
     2. Bglycogen
     3. Cphosphoglycerate
     4. Dpyruvate
     5. Eribulose 5-phosphate
135. 135Almost all of the oxygen (O2) one consumes in breathing is converted to:
     

     1. Aacetyl-CoA.
     2. Bcarbon dioxide (CO2).
     3. Ccarbon monoxide and then to carbon dioxide.
     4. Dnone of the above.
     5. Ewater.
136. 136A new compound isolated from mitochondria is claimed to represent a previously unrecognized carrier in the electron transfer chain. It is given the name coenzyme Z. Which line of evidence do you feel is the least conclusive in assigning this compound a position in the electron transfer chain?

     1. AAlternate oxidation and reduction of the mitochondrion-bound coenzyme Z can be readily demonstrated.
     2. BRemoval of coenzyme Z from the mitochondria results in a decreased rate of oxygen consumption.
     3. CThe rate of oxidation and reduction of mitochondrion-bound coenzyme is of the same order of magnitude as the overall rate of electron transfer in mitochondria as measured by oxygen consumption.
     4. DThe reduction potential of Z is between that of two compounds known to participate in the electron transport chain
     5. EWhen added to a mitochondrial suspension, coenzyme Z is taken up very rapidly and specifically by the mitochondria.
137. 137Antimycin A blocks electron transfer between cytochromes b and c1. If intact mitochondria were incubated with antimycin A, excess NADH, and an adequate supply of O2, which of the following would be found in the oxidized state?

     1. ACoenzyme Q
     2. BCytochrome a3
     3. CCytochrome b
     4. DCytochrome e
     5. ECytochrome f
138. 138Cyanide, oligomycin, and 2,4-dinitrophenol (DNP) are inhibitors of mitochondrial aerobic phosphorylation. Which of the following statements correctly describes the mode of action of the three inhibitors?
     

     1. ACyanide and 2,4-dinitrophenol inhibit the respiratory chain, and oligomycin inhibits the synthesis of ATP.
     2. BCyanide inhibits the respiratory chain, whereas oligomycin and 2,4-dinitrophenol inhibit the synthesis of ATP.
     3. CCyanide, oligomycin, and 2,4-dinitrophenol compete with O2 for cytochrome oxidase (Complex
        IV).
     4. DOligomycin and cyanide inhibit synthesis of ATP; 2,4-dinitrophenol inhibits the respiratory
        chain.
     5. EOligomycin inhibits the respiratory chain, whereas cyanide and 2,4-dinitrophenol prevent the
        synthesis of ATP.
139. 139In the reoxidation of QH2 by purified ubiquinone-cytochrome c reductase (Complex III) from heart muscle, the overall stoichiometry of the reaction requires 2 mol of cytochrome c per mole of QH2 because:

     1. Acytochrome c is a one-electron acceptor, whereas QH2 is a two-electron donor.
     2. Bcytochrome c is a two-electron acceptor, whereas QH2 is a one-electron donor.
     3. Ccytochrome c is water soluble and operates between the inner and outer mitochondrial membranes
     4. Dheart muscle has a high rate of oxidative metabolism, and therefore requires twice as much cytochrome c as QH2 for electron transfer to proceed normally.
     5. Etwo molecules of cytochrome c must first combine physically before they are catalytically active.
140. 140If electron transfer in tightly coupled mitochondria is blocked (with antimycin A) between cytochrome b and cytochrome c1, then:

     1. Aall A TP synthesis will stop.
     2. BATP synthesis will continue, but the P/O ratio will drop to one.
     3. Celectron transfer from NADH will cease, but O2 uptake will continue.
     4. Delectron transfer from succinate to O2 will continue unabated.
     5. Eenergy diverted from the cytochromes will be used to make ATP, and the P/O ratio will rise.
141. 141In normal mitochondria, the rate of NADH consumption (oxidation) will:

     1. Abe increased in active muscle, decreased in inactive muscle.
     2. Bbe very low if the ATP synthase is inhibited, but increase when an uncoupler is added.
     3. Cdecrease if mitochondrial ADP is depleted.
     4. Ddecrease when cyanide is used to prevent electron transfer through the cytochrome a + a3 complex.
     5. EAll of the above are true.
142. 142Which of the following statements about the chemiosmotic theory is correct?

     1. AElectron transfer in mitochondria is accompanied by an asymmetric release of protons on one side of the inner mitochondrial membrane.
     2. BIt predicts that oxidative phosphorylation can occur even in the absence of an intact inner mitochondrial membrance.
     3. CThe effect of uncoupling reagents is a consequence of their ability to carry electrons through membranes.
     4. DThe membrane ATP synthase has no significant role in the chemiosmotic theory.
     5. EAll of the above are correct.
143. 143Which of the following statements about the chemiosmotic theory is false?

     1. AElectron transfer in mitochondria is accompanied by an asymmetric release of protons on one side of the inner mitochondrial membrane.
     2. BEnergy is conserved as a transmembrane pH gradient.
     3. COxidative phosphorylation cannot occur in membrane-free preparations.
     4. DThe effect of uncoupling reagents is a consequence of their ability to carry protons through
        membranes.
     5. EThe membrane ATPase, which plays an important role in other hypotheses for energy coupling,
        has no significant role in the chemiosmotic theory.
144. 144Upon the addition of 2,4-dinitrophenol (DNP) to a suspension of mitochondria carrying out oxidative phosphorylation linked to the oxidation of malate, all of the following occur except:
     

     1. Aoxygen consumption decreases.
     2. Boxygen consumption increases.
     3. Cthe P/O ratio drops from a value of approximately 2.5 to 0.
     4. Dthe proton gradient dissipates.
     5. Ethe rate of transport of electrons from NADH to O2 becomes maximal.
145. 145Uncoupling of mitochondrial oxidative phosphorylation:

     1. Aallows continued mitochondrial ATP formation, but halts O2 consumption.
     2. Bhalts all mitochondrial metabolism.
     3. Chalts mitochondrial ATP formation, but allows continued O2 consumption.
     4. Dslows down the citric acid cycle.
     5. Eslows the conversion of glucose to pyruvate by glycolysis.
146. 1462,4-Dinitrophenol and oligomycin inhibit mitochondrial oxidative phosphorylation. 2,4-Dinitrophenol is an uncoupling agent; oligomycin blocks the ATP synthesis reaction itself. Therefore, 2,4-dinitrophenol will:

     1. Aallow electron transfer in the presence of oligomycin.
     2. Ballow oxidative phosphorylation in the presence of oligomycin.
     3. Cblock electron transfer in the presence of oligomycin.
     4. Ddiminish O2 consumption in the presence of oligomycin
     5. Edo none of the above.
147. 147Which of the following statements about energy conservation in the mitochondrion is false?

     1. ADrug that inhibits the ATP synthase will also inhibit the flow of electrons down the chain of carriers.
     2. BFor oxidative phosphorylation to occur, it is essential to have a closed membranous structure with an inside and an outside.
     3. CThe yield of ATP per mole of oxidizable substrate depends on the substrate.
     4. DUncouplers (such as dinitrophenol) have exactly the same effect on electron transfer as inhibitors
        such as cyanide; both block further electron transfer to oxygen.
     5. EUncouplers “short circuit” the proton gradient, thereby dissipating the proton motive force as
        heat.
148. 148Which of the following is correct concerning the mitochondrial ATP synthase?

     1. AIt can synthesize ATP after it is extracted from broken mitochondria.
     2. BIt catalyzes the formation of ATP even though the reaction has a large positive ΔG'°.
     3. CIt consists of F0 and F1 subunits, which are transmembrane (integral) polypeptides.
     4. DIt is actually an A TPase and only catalyzes the hydrolysis of A TP .
     5. EWhen it catalyzes the ATP synthesis reaction, the ΔG'° is actually close to zero.
149. 149When the ΔG'° of the ATP synthesis reaction is measured on the surface of the ATP synthase enzyme, it is found to be close to zero. This is thought to be due to:

     1. Aa very low energy of activation.
     2. Benzyme-induced oxygen exchange.
     3. Cstabilization of ADP relative to ATP by enzyme binding.
     4. Dstabilization of ATP relative to ADP by enzyme binding.
     5. Enone of the above.
150. 150During oxidative phosphorylation, the proton motive force that is generated by electron transport is used to:

     1. Acreate a pore in the inner mitochondrial membrane.
     2. Bgenerate the substrates (ADP and Pi) for the ATP synthase.
     3. Cinduce a conformational change in the ATP synthase.
     4. Doxidize NADH to NAD+.
     5. Ereduce O2 to H2O.
151. 151The oxidation of a particular hydroxy substrate to a keto product by mitochondria has a P/O ratio of less than 2. The initial oxidation step is very likely directly coupled to the:

     1. Aoxidation of a flavoprotein.
     2. Boxidation of a pyridine nucleotide.
     3. Creduction of a flavoprotein.
     4. Dreduction of a pyridine nucleotide.
     5. Ereduction of cytochrome a3.
152. 152The relative concentrations of ATP and ADP control the cellular rates of:

     1. Aglycolysis.
     2. Boxidative phosphorylation.
     3. Cpyruvate oxidation.
     4. Dthe citric acid cycle.
     5. Eall of the above.
153. 153The rate of oxidative phosphorylation in mitochondria is controlled primarily by:

     1. Afeedback inhibition by CO2.
     2. Bthe availability of NADH from the TCA cycle.
     3. Cthe concentration of citrate (or) the glycerol-3-phosphate shuttle.
     4. Dthe mass-action ratio of the ATD-ADP system.
     5. Ethe presence of thermogenin.
154. 154Mammals produce heat by using the endogenous uncoupling agent:

     1. Athe small molecule 2-4-Dinitrophenol synthesized by the cell.
     2. Bthe protein thermogenin.
     3. Cthe protein thioredoxin.
     4. Dthe protein cytochrome c.
     5. Ea modified form of the FoF1 ATPase.
155. 155Which one of the following best describes the role of mitochondria in apoptosis?

     1. AEscape of cytochrome c into the cytoplasm.
     2. BIncreased rate of fatty acid β-oxidation.
     3. CIncrease in permeability of outer membrane.
     4. DUncoupling of oxidative phosphorylation.
     5. EBoth A and C are correct.
156. 156Mutations in mitochondrial genes play a role in each of the following diseases except:

     1. Aadult onset diabetes
     2. Bcystic fibrosis
     3. Chypertrophic cardiomyopathy
     4. Dleber's hereditary optic neuropathy
     5. Emyoclonic epilepsy
157. 157Which one of the following statements about photophosphorylation is false?

     1. AIt can be uncoupled from electron flow by agents that dissipate the proton gradient.
     2. BThe difference in pH between the luminal and stromal side of the thylakoid membrane is 3 pH
        units.
     3. CThe luminal side of the thylakoid membrane has a higher pH than the stromal side.
     4. DThe number of ATPs formed per oxygen molecule is about three.
     5. EThe reaction centers, electron carriers, and ATP-forming enzymes are located in the thylakoid
        membrane.

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Test sobre Metabolism, creado por Stephanie T el 09/11/2018.

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Stephanie T

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