Free energy Original Scenario-Based Practice

Questions

1. 1.

   Deep within an isolated subterranean cavern, astrobiologists discover an exotic chemotrophic bacterium that synthesizes a protective matrix polymer through an endergonic reaction with a positive free energy change ($\Delta G > 0$). To drive this thermodynamically unfavorable process, the bacterium couples the synthesis directly to the enzymatic hydrolysis of an energy-rich phosphate compound exhibiting a strongly negative free energy change ($\Delta G < 0$). Which statement correctly explains why this metabolic coupling enables the synthesis of the matrix polymer to proceed spontaneously?

   • A) The overall free energy change of the coupled reaction becomes zero, establishing a state of dynamic chemical equilibrium that pulls reactants toward products.
   • B) The energy-rich phosphate compound acts as a biological catalyst that permanently lowers the activation energy barrier without altering the net free energy.
   • C) The net change in free energy for the coupled reactions is negative, making the combined pathway exergonic and thermodynamically favorable.
   • D) The coupled reaction transfers thermal energy to the surroundings, decreasing total entropy and forcing the synthetic reaction forward.

Answers and step-by-step solutions appear after you finish the test.