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1.2 Thermodynamics β Test 1
Q1. Which form of nucleotide represents the major energy currency of the cell?β Adenosine-5'-triphosphate (ATP)
Q2. Which of the following processes does NOT generate ATP/GTP?β Calvin cycle
Q3. One reason for the high energy of hydrolysis of ATP is:β Resonance stabilization of the products
Q4. Unfavourable reactions occur in cells by coupling to ATP β ADP + Pi because for ATP hydrolysis:β ΞGΒ°' is negative (exergonic)
Q5. The high energy of ATP hydrolysis is primarily due to:β Electrostatic repulsion between negatively charged phosphate oxygens
Q6. Hydrolysis of one mole of ATP to ADP releases approximately how many calories?β 7,300
Q7. Glucose and hexanoic acid each have 6 carbons. For complete oxidation, net ATP yield:β Hexanoic acid produces more ATP
Q8. Reactions with positive standard free-energy change (ΞGΒ°' > 0) occur in cells mainly by:β Coupling to other exergonic reactions
Q9. Reactions with ΞGΒ°' > 0 can be made to occur in cells by:β Coupling with exergonic reactions via a common intermediate
Q10. Reactions with ΞGΒ°' > 0 are routinely carried out by organisms because of:β Energy from ATP hydrolysis / coupling to exergonic reactions
Q11. Which is a fundamental mode of energy exchange in biological systems?β ATPβADP cycle
Q12. The equation relating free-energy change to enthalpy and entropy (constant T, P) is:β ΞG = ΞH β TΞS
Q13. Why do phosphoanhydride linkages have a high ΞG of hydrolysis?β Resonance stabilization of products exceeds that of the compound
Q14. Which compound has a HIGHER phosphate group-transfer potential than ATP?β Phosphoenolpyruvate
Q15. Which compound has the highest free-energy change on hydrolysis?β Phosphoenolpyruvate
Q16. Which compound has a higher phosphate group-transfer potential than ATP (set 2)?β Phosphoenolpyruvate
Q17. Which high-energy compound releases the maximum energy on hydrolysis?β Phosphoenolpyruvate
Q18. Which compound has a higher group-transfer potential for phosphate than ATP (set 3)?β 2-phosphoenolpyruvate
Q19. The standard reduction potential EΒ°' for NADβΊ + HβΊ + 2eβ» β NADH (pH 7, 25Β°C) is about:β β0.320 V
1.2 Thermodynamics β Test 2
Q20. Which of the following is NOT an electron carrier of the electron transport chain?β NADP
Q21. Which reaction will NOT proceed in the direction written (reactants 1:1)?β ATP + creatine β creatine phosphate + ADP
Q22. Given Fumarate + 2HβΊ + 2eβ» β Succinate (EΒ°'=+0.031 V) and FAD + 2HβΊ + 2eβ» β FADHβ (EΒ°'=β0.320 V), which statement is correct?β Coupled: Fumarate + FADHβ β Succinate + FAD; FAD is reduced to FADHβ by ... ; ΞEΒ°' = 0.351 V
Q23. Redox reactions with positive standard redox potential change (ΞEΒ°' > 0) have:β Negative ΞGΒ°
Q24. What is reduction potential?β The tendency of an atom/molecule to gain an electron
Q25. Which biochemical reaction shows the highest (most negative) standard free-energy change?β Palmitate + 23 Oβ β 16 COβ + 16 HβO
Q26. Which phosphorylated compound yields the highest energy on hydrolysis?β Phosphoenolpyruvate
Q27. Standard redox potentials: NADβΊ/NADH (β0.315 V), FAD/FADHβ (β0.219 V). The ΞGΒ°' for oxidation of NADH by FAD is about:β β18.5 kJ/mol
Q28. Beaker X has 100 mL water at 80Β°C; beaker Y has 200 mL water at 20Β°C. Mixed together, the temperature is closest to:β 40Β°C
Q29. Beaker A: 100 mL fluid at 80Β°C; beaker B: 200 mL same fluid at 20Β°C. Mixed, the temperature is:β 40Β°C
Q30. Which bond in biomolecules has the highest bond dissociation energy (kJ/mol)?β C=O
Q31. Relative strength of interactions in protein structure (weakest β strongest) is:β Hydrophobic < hydrogen bond < ionic bond < covalent bond
Q32. Which term does NOT refer to a weak interaction between biological molecules?β Covalent
Q33. Which structure exhibits a net dipole moment?β Ξ±-helix
Q34. A binds L1 with dissociation constant K1 and L2 with K2. If K2 > K1, which complex is more stable?β AL1 is more stable than AL2
Q35. An increase in entropy occurs in which situation?β Release of inorganic phosphate during ATP hydrolysis
Q36. Which one is NOT an entropy-driven process?β Base pairing
Q37. If both ΞH and ΞS are negative, the reaction (ΞG = ΞH β TΞS):β Is exergonic/favoured below T = ΞH/ΞS
1.2 Thermodynamics β Test 3
Q38. For A β B, ΞH = β7 kJ/mol and ΞS = β25 J/KΒ·mol at 298 K. ΞG and spontaneity?β +450 J/mol, not spontaneous
Q39. ΞGΒ°' = +1.4 kcal/mol at 37Β°C for X β Y. The equilibrium ratio [X]/[Y] is approximately:β 10:1
Q40. Which isotope produces the highest kinetic isotope effect?β Β³H (tritium)
Q41. Glucose monomers join by glycosidic bonds to form cellulose. The changes in free energy, enthalpy and entropy are:β +ΞG, +ΞH, βΞS
Q42. For a spontaneous reaction, ΞG should be:β Negative
Q43. Evaluate: (I) A reaction is spontaneous when it can proceed in either direction. (II) A spontaneous process can occur with a large decrease in entropy.β I False, II True
Q44. A process is endothermic yet energetically favourable. Which is correct?β ΞH positive, ΞS positive, ΞG negative
Q45. If the equilibrium constant is greater than one, the Gibbs free-energy change is:β Negative
Q46. ΞGΒ°' = +1.4 kcal/mol at 37Β°C for X β Y. The equilibrium ratio [X]/[Y] most closely approximates:β 10:1
Q47. In NADH + HβΊ + E-FMN β NADβΊ + E-FMNHβ, the electron acceptor is:β E-FMN
Q48. A reaction that occurs spontaneously (ΞG negative) is termed:β Exergonic
Q49. The direction of a chemical reaction is best predicted by:β ΞG
Q50. The first law of thermodynamics, applied to living cells, states that:β Energy is conserved β it can be transformed but not created or destroyed
Q51. The second law of thermodynamics implies that for any spontaneous process, the total entropy of the system plus surroundings:β Increases
Q52. Living organisms maintain their high internal order without violating the second law because they are:β Open systems that exchange energy and matter with the surroundings
Q53. Enthalpy (ΞH) of a reaction represents the:β Heat content change at constant pressure
Q54. Under cellular (non-standard) conditions, the actual free-energy change ΞG depends on ΞGΒ°' and:β The actual concentrations of reactants and products
Q55. ATP is described as having an intermediate phosphoryl-transfer potential. The biological significance is that ATP can:β Act as a versatile carrier β accepting Pi from high-energy donors and donating it to lower-energy acceptors