Thermodynamics & Statistical Mechanics in Biology – MCQs 50 Score: 0 Attempted: 0/50 Subscribe 1. The first law of thermodynamics states: (A) Energy can be created (B) Energy can be destroyed (C) Energy is conserved (D) Heat and work are unrelated 2. Gibbs free energy is useful in biology because it indicates: (A) Reaction spontaneity (B) Heat capacity (C) Molecular weight (D) Cell size 3. A biochemical reaction is spontaneous when: (A) ΔG < 0 (B) ΔG > 0 (C) ΔS < 0 (D) ΔH > 0 4. Entropy (S) measures: (A) Disorder or randomness (B) Mass of molecules (C) Enthalpy change (D) Pressure-volume work 5. The second law of thermodynamics states: (A) Entropy of an isolated system increases (B) Energy is destroyed in reactions (C) Mass is lost in closed systems (D) Heat never flows spontaneously 6. Standard free energy change (ΔG°) relates to equilibrium constant by: (A) ΔG° = –RT ln K (B) ΔG° = RT ln K (C) ΔG° = K/RT (D) ΔG° = 0 at all times 7. The unit of entropy is: (A) J·K⁻¹ (B) J·mol⁻¹ (C) J·s (D) J·kg⁻¹ 8. The free energy equation is: (A) ΔG = ΔH – TΔS (B) ΔG = ΔH + TΔS (C) ΔG = ΔH × ΔS (D) ΔG = ΔH / ΔS 9. At equilibrium, ΔG is: (A) 0 (B) Positive (C) Negative (D) Undefined 10. ATP hydrolysis is central to metabolism because: (A) It releases free energy to drive reactions (B) It decreases entropy of the cell (C) It consumes energy always (D) It increases DNA replication rate 11. The Boltzmann equation S = k ln W relates: (A) Entropy to microstates (B) Heat to work (C) Pressure to volume (D) Force to acceleration 12. The constant k in Boltzmann’s formula is: (A) Boltzmann constant (B) Planck constant (C) Avogadro’s constant (D) Gas constant 13. Enthalpy (ΔH) represents: (A) Heat content of a system (B) Randomness in molecules (C) Protein folding rate (D) DNA mutations 14. Which distribution describes molecular speeds in gases? (A) Maxwell–Boltzmann (B) Poisson (C) Gaussian (D) Fermi–Dirac 15. The canonical ensemble is defined by: (A) Constant N, V, T (B) Constant N, P, T (C) Constant μ, V, T (D) Constant E, V, N 16. The grand canonical ensemble is defined by: (A) Constant μ, V, T (B) Constant N, V, T (C) Constant P, V, T (D) Constant E, V, N 17. In protein folding, entropy changes are driven by: (A) Hydrophobic effect (B) Gravity (C) Electrical forces only (D) Random heat flow 18. Entropy of a pure crystalline substance at absolute zero is: (A) Zero (B) Infinite (C) Maximum (D) Undefined 19. Helmholtz free energy is defined as: (A) A = U – TS (B) A = H – TS (C) A = G – PV (D) A = U + TS 20. The zeroth law of thermodynamics defines: (A) Temperature (B) Energy conservation (C) Entropy increase (D) Heat capacity 21. Entropy change in the universe during spontaneous processes is: (A) Positive (B) Negative (C) Zero (D) Infinite 22. Which thermodynamic process occurs at constant pressure? (A) Isobaric (B) Isochoric (C) Adiabatic (D) Isothermal 23. Which process occurs without heat exchange? (A) Adiabatic (B) Isothermal (C) Isochoric (D) Isobaric 24. A highly ordered biological structure corresponds to: (A) Low entropy (B) High entropy (C) Maximum enthalpy (D) Zero free energy 25. In biology, non-equilibrium thermodynamics is applied to: (A) Transport and metabolic processes (B) DNA replication accuracy (C) Cell size regulation (D) Protein weight 26. The statistical weight (W) in Boltzmann’s equation represents: (A) Number of microstates (B) Heat per unit mass (C) Pressure-volume work (D) Rate constant 27. Which law explains why absolute zero cannot be reached? (A) Third law (B) First law (C) Second law (D) Zeroth law 28. In an isothermal process, which parameter remains constant? (A) Temperature (B) Pressure (C) Entropy (D) Volume 29. Entropy production in living cells reflects: (A) Irreversible processes (B) Equilibrium (C) Reversible processes (D) Constant energy 30. The ergodic hypothesis states that: (A) Time averages equal ensemble averages (B) Energy is always conserved (C) Heat equals work (D) All systems move toward equilibrium 31. The dissociation constant (Kd) in ligand binding reflects: (A) Binding affinity (B) Protein weight (C) Free energy of folding (D) Cell membrane potential 32. Entropy is maximized at: (A) Equilibrium (B) Nonequilibrium (C) Zero temperature (D) Absolute zero 33. Heat capacity (C) is defined as: (A) dQ/dT (B) dT/dQ (C) ΔG/ΔS (D) ΔH/ΔS 34. The partition function (Z) in statistical mechanics represents: (A) Sum over all possible states (B) Energy per particle (C) Pressure times volume (D) Force per unit area 35. The molecular partition function includes: (A) Translational, rotational, vibrational, electronic states (B) Only translational states (C) Only electronic states (D) Only vibrational states 36. A reaction with ΔH < 0 and ΔS > 0 is: (A) Always spontaneous (B) Always non-spontaneous (C) Spontaneous only at high T (D) Spontaneous only at low T 37. A reaction with ΔH > 0 and ΔS < 0 is: (A) Always non-spontaneous (B) Always spontaneous (C) Spontaneous at high T (D) Spontaneous at low T 38. The third law of thermodynamics states: (A) Entropy of a perfect crystal at 0 K is zero (B) Energy cannot be destroyed (C) Heat always flows from hot to cold (D) Temperature is proportional to energy 39. In enzyme catalysis, free energy barrier lowering increases: (A) Reaction rate (B) Entropy (C) Heat capacity (D) Pressure 40. In osmosis, solvent movement is driven by: (A) Chemical potential difference (B) Random entropy (C) Temperature only (D) Pressure-volume work 41. ΔG° of ATP hydrolysis under standard conditions is approximately: (A) –30.5 kJ/mol (B) –10 kJ/mol (C) –100 kJ/mol (D) –300 kJ/mol 42. The equilibrium constant increases when ΔG° is: (A) More negative (B) More positive (C) Zero (D) Undefined 43. The Maxwell relations are derived from: (A) Thermodynamic potentials (B) Statistical weight (C) Entropy equations (D) Free energy landscapes 44. Biological order is maintained by: (A) Exporting entropy to the environment (B) Eliminating entropy (C) Stopping energy transfer (D) Zero enthalpy reactions 45. A reversible process is characterized by: (A) No net entropy production (B) Maximum entropy production (C) Constant ΔH (D) ΔG always positive 46. In statistical mechanics, macrostates are defined by: (A) Observable thermodynamic quantities (B) Single molecular positions (C) DNA bases only (D) Enzyme active sites only 47. A microstate refers to: (A) Specific microscopic configuration of a system (B) Energy per mole (C) Heat exchange (D) Average pressure 48. Free energy landscapes are used to study: (A) Protein folding pathways (B) DNA sequence length (C) ATP concentration (D) Gas pressure 49. The law of mass action is consistent with: (A) Statistical mechanics and thermodynamics (B) Newton’s laws (C) General relativity (D) Maxwell’s equations 50. 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