Section ііi Metabolic pathways and bioenergetics. Tricarboxylic acid cycle. Biological oxidation and oxidative phopshorylation

1. When atp forms amp:

1. Inorganic pyrophosphate is produced

2. Inorganic phosphorous is produced

3. Phsophagen is produced

4. ADP is produced

5. No energy is produced

2. Standard free energy (ΔG°) of hydrolysis of ATP to ADP + Pi is:

1. –30.5 KJ/mol

2. –49.3 KJ/mol

3. –4.93 KJ/mol

4. –20.9 KJ/mol

5. – 2.5 KJ/mol

3. Standard free energy (ΔG°) of hydrolysis of ADP to AMP + Pi is:

1. –27.6 KJ/mol

2. –43.3 KJ/mol

3. –30.5 KJ/mol

4. –15.9 KJ/mol

5. 2.5 KJ/mol

4. Standard free energy (ΔG°) of hydrolysis of phosphoenolpyruvate is:

1. –61.9 KJ/mol

2. –43.1 KJ/mol

3. –14.2 KJ/mol

4. –9.2 KJ/mol

5. –4.2 KJ/mol

5. Standard free energy (ΔG°) of hydrolysis of creatine phosphate is:

1. –43.1 KJ/mol

2. –51.4 KJ/mol

3. –30.5 KJ/mol

4. –15.9 KJ/mol

5. –9.2 KJ/mol

6. Which of the following compounds would you expect to liberate the least free energy on hydrolysis?

1. AMP

2. ATP

3. ADP

4. Phosphoenolpyruvate

5. Phosphocreatine

7. Which of the following compounds would you expect to liberate the highest free energy on hydrolysis?

1. Phosphoenolpyruvate

2. ATP

3. ADP

4. AMP

5. Phosphocreatine

8. The degradative processess are categorized under the heading of:

1. Catabolism

2. Anabolism

3. Metabolism

4. Amphibolism

5. None of the above

9. Most of the metabolic pathways are either anabolic or catabolic. Which of the following pathways is considered as “amphibolic” in nature?

A. TCA cycle

B. Glycolytic pathway

C. Lipolysis

D. Glycogenesis

E. Pentosophosphate pathway

10. Enzymes of tricaboxylic acid cycle are located:

A. In the mitochondrial matrix

B. On the outer surface of the outer mitochondrial membrane

C. On the inner surface of the outer mitochondrial membrane

D. In the inner mitochondrial membrane

E. In the intermembrane space

11. Which of the following statements regarding TCA cycle is true?

A. It is amphibolic in nature

B. It occurs in cytosol

C. It contains no intermediates for Gluconeogenesis

D. It is an anaerobic process

E. It occurs in nucleus

12. Before pyruvic acid enters the TCA cycle it must be converted to:

A. Acetyl CoA

B. Lactate

C. -ketoglutarate

D. Citrate

E. Succinate

13. The formation of citrate from oxaloacetate and acetyl CoA is:

A. Condensation

B. Reduction

C. Oxidation

D. Hydrolysis

E. Isomerisation

14. Tricarboxylic acid cycle to be continuous requires the regeneration of:

1. Oxaloacetic acid

2. Pyruvic acid

3. α-oxoglutaric acid

4. Malic acid

5. Succinic acid

15. The next principal substrate is involved into oxidation in tricarboxylic acid cycle:

A. Acetyl-CoA

B. Pyruvate

C. Lactate

D. Glucose

E. Glutamate

16. What substance is the main fuel material for TCA cycle?

A. Acetyl-CoA

B. Glucose

C. Amino acids

D. Fatty acids

E. Succinyl-CoA

17. Malate dehydrogenase is an enzyme dependent from the presence of the next cofactor:

1. NAD⁺

2. TPP

3. Coenzyme A

4. NADP

5. FMN

18. Substrate level phosphorylation in TCA cycle is in step:

A. Succinate thiokinase

B. Malate dehydrogenase

C. Aconitase

D. Isocitrate dehydrogenase

E. Succinate dehydrogenase

19. α-ketoglutarate dehydrogenase complex contains derivatives of the following vitamin:

1. Thiamine

2. Folic acid

3. Retinol

4. Pyridoxine

5. Ubiquinone

20. Which of the following enzymes catalyze convetion of succinate to fumarate:

1. Succinate dehydrogenase

2. Aconitase

3. Fumarase

4. Citrate synthase

5. Isocitrate dehydrogenase

21. An allosteric enzyme responsible for controlling the rate of TCA cycle is:

A. Isocitrate dehydrogenase

B. Malate dehydrogenase

C. Fumarase

D. Aconitase

E. Succinate dehydrogenase

22. A principle of succinate dehydrogenase activity determination is based on the reduction of methylene blue with reduced form of the coenzyme. What coenzyme is incorporated into the structure of succinate dehydrogenase?

A. FAD

B. NAD

C. FMN

D. TPP

E. PALP

23. Out of 24 mols of ATP formed in TCA cycle, 2 molecules of ATP can be formed at “substrate level” by which of the following reaction?

A. Succinyl-coA→Succinic acid

B. Isocitrate→Oxaloacetate

C. Succinic acid→Fumarate

D. Citric acid → Isocitric acid

E. Fumarate→Malate

24. Which of the following enzymes catalyze reaction: Acetyl-CoA + oxaloacetate → citrate + CoASH:

1. Citrate synthase

2. Succinate dehydrogenase

3. Fumarase

4. Aconitase

5. Isocitrate dehydrogenase

25. Citrate is converted to isocitrate by aconitase which contains:

A. Fe²⁺

B. Ca²⁺

C. Zn²⁺

D. Mg²⁺

E. Mn²⁺

26. If all the enzymes, intermediates and cofactors of the citric acid cycle as well as an excess of the starting substrate acetyl-CoA are present and functional in an organelle free solution at the appropriate pH, which of the following factors of the citric acid cycle would prove to be rate limiting?

A. Molecular oxygen

B. Half life of enzyme

C. Turnover of intermediates

D. Reduction of cofactors

E. Temperature

27. In TCA cycle, oxalosuccinate is converted to α-ketoglutarate by the enzyme:

A. Isocitrate dehydrogenase

B. Fumarase

C. Aconitase

D. Succinase

E. Succinate dehydrogenase

28. In citric acid cycle, GDP is phosphorylated by:

A. Succinate dehydrogenase

B. Aconitase

C. Succinate thiokinase

D. Fumarase

E. Isocitrate dehydrogenase

29. All of the following are intermediates of citric acid cycle except:

A. Pyruvate

B. Oxaloacetate

C. Oxalosuccinate

D. Fumarate

E. Citrate

30. The reaction succinyl-CoA to succinate requires:

A. GDP

B. ADP

C. CDP

D. NADP⁺

E. NAD⁺

31. An aneplerotic reaction which sustains the availability of oxaloacetate is the carboxylation of:

A. Pyruvate

B. Glutamate

C. Citrate

D. Succinate

E. Aconitate

32. Which from listed below substances is used as an inhibitor in studies of TCA cycle functioning?

1. Malonate

2. ATP

3. NAD

4. Aconitate

5. Isocitrate

33. A specific inhibitor for succinate dehydrogenase is:

A. Malonate

B. Succinate

C. Citrate

D. Cyanide

E. Aconitate

34. The inhibition of isocitrate dehydrogenase by NADH is:

A. Feedback inhibition

B. Non-competitive inhibition

C. Uncompetitive inhibition

D. Competitive inhibition

E. Irreversible

35. Which of the following substances activate isocitrate dehydrogenase:

1. ADP

2. FADH₂

3. NADH+H⁺

4. ATP

5. Mg²⁺

36. The positive allosteric modifier of the enzyme pyruvate carboxylase?

A. Acetyl CoA

B. Biotin

C. Oxaloacetate

D. ATP

E. ADP

37. How many moles of FADH₂ are produced in process of oxidation of 0,25 mole of acetyl-CoA in tricarboxylic acid cycle?

1. 0,25

2. 0,1

3. 0,5

4. 1,0

5. 1,5

38. How many moles of NADH+H⁺ are produced in process of oxidation of 0,25 mole of acetyl-CoA in tricarboxylic acid cycle?

1. 0,75

2. 0,25

3. 0,1

4. 0,5

5. 1,0

39. The number of molecules of ATP produced by the total oxidation of acetyl CoA in TCA cycle is:

A. 12

B. 8

C. 10

D. 6

E. 14

40. Tricarboxylic acid cycle (TCA) generates reduced forms of NAD and FAD which are used in:

1. Respiratory chain of enzymes in mitochondria

2. Synthesis of fatty acids

3. Biosynthesis of ATP by substrate phosphorylation

4. Biosynthesis of ATP by oxidative phosphorylation

5. Biosynthesis of purine nucleotides

41. The inhibition of succinate dehydrogenase by malonate is:

A. Competitive inhibition

B. Non-competitive inhibition

C. Uncompetitive inhibition

D. Feedback inhibition

E. Irreversible

42. The number of ATP produced in the succinate dehydrogenase step is:

A. 2

B. 1

C. 3

D. 4

E. 5

43. Most of protons and electrons which are further involved into mitochondrial respiratory chain are supplied from the next metabolic pathways:

1. Tricarboxylic acid (TCA) cycle

2. Glycolysis

3. Pyruvate dehydrogenase complex

4. Oxidation of fatty acids

5. Cleavage of proteins

44. In citric acid cycle, NAD is reduced in:

A. Three reactions

B. Two reactions

C. One reactions

D. Four reactions

E. Five reactions

45. The mitochondrial electron transport chain carriers are located in:

1. Inner mitochondrial membrane

2. Mitochondrial matrix

3. Intermembranous space of mitochondria

4. On the inner surface of the external mitochondrial membrane

5. On the outer surface of the external mitochondrial membrane

46. Most of protons and electrons which are further involved into mitochondrial respiratory chain are supplied from the next metabolic pathways:

1. Tricarboxylic acid (TCA) cycle

2. Glycolysis

3. Pyruvate dehydrogenase complex

4. Oxidation of fatty acids

5. Cleavage of proteins

47. The oxidation-reduction system having the highest redox potential is:

1. NAD⁺/NADH

2. Ubiquinone ox/red

3. Fe³⁺ cytochrome a/Fe²⁺

4. Fe³⁺ cytochrome b/Fe²⁺

E. Fe³⁺ cytochrome c₁/Fe²⁺

48. Redox potential (EO volts) of NAD+/NADH is:

A. –0.32

B. –0.67

C. –0.12

D. +0.03

E. –0.88

49. Redox potential (EO volts) of ubiquinone, ox/red system is:

A. +0.04

B. +0.08

C. +0.10

D. +0.29

E. + 0.35

50. The oxidation-reduction system having the lowest redox potential is:

A. Fe³⁺ cytochrome a/Fe²⁺

B. Ubiquinone ox/red

C. Fe³⁺ cytochrome b/Fe²⁺

D. Fe³⁺ cytochrome c₁/Fe²⁺

E. NAD⁺/NADH

51. The correct sequence of cytochrome carriers in respiratory chain is:

A. Cyt b→cyt c₁→cyt c→cyt aa₃

B. Cyt aa₃→ cyt b→cyt c→cyt c₁

C. Cyt b→cyt c→cyt c₁→cyt aa₃

D. Cyt b→cyt aa₃→cyt c→ cyt c

E. Cyt aa₃→ cyt c₁→cyt c→ cyt b

52. The sequence of the redox carriers in respiratory chain is:

1. NAD→FMN→CoQ→cyt b→cyt c₁→cyt c→cytaa₃ → O₂

2. FMN→CoQ →NAD→cyt b→cyt aa₃→cyt c₁→cyt c → O₂

3. NAD→FMN→CoQ→ cyt c₁→cyt c→cyt b→cytaa₃ → O₂

4. NAD→FMN→CoQ→cyt b→ cyt aa₃ cyt c₁→cyt

5. FMN→NAD→ CoQ→cyt b→ cyt aa₃ cyt c₁→cyt

53. All of the following electron carriers are components of the mitochondrial electron transport chain EXEPT:

1. NADP⁺

2. NAD

3. FMN

4. FAD

5. Coenzyme Q₁₀

54. Cytochrome c of mitochondrial respiratory chain transfers electrons:

1. To cytochrome oxidase

2. From FAD-H₂

3. From NADP-H₂

4. From ubiquinon

5. To cytochrome b₂

55. In respirastory chain electrons only are transported by:

1. Cytochrome c

2. FAD

3. NAD

4. Ubiquinon

5. Succinate dehydrogenase

56. Dehydrogenases are enzymes which catalyze transfer of the next structural elements of the molecule:

1. Hydrogen

2. Phosphate group

3. Methyl group

4. Amino group

5. Oxygen anion

57. Which of the following vitamins is precursor of flavine mononucleotide?

1. Vitamin B₂

2. Vitamin A

3. Vitamin B₆

4. Vitamin C

5. Vitamin D

58. A component of the respiratory chain in mitochondria is;

A. Coenzyme Q

B. Coenzyme A

C. Acetyl coenzyme

D. Coenzyme containing thiamin

E. Coenzyme B

59. The component of respiratory chain enzymes cytochrome oxidase (cytochrome a+a₃₎, operates as a transporter of:

A. Electrons