Thermodynamics in biochemistry: the free energy change (ΔG) of a reaction is best described as the amount of energy that is…

Introduction / Context:
Free energy change, ΔG, indicates reaction spontaneity and the capacity to do non-expansion work under constant temperature and pressure. In cellular metabolism, ΔG helps predict whether reactions proceed forward, require coupling, or depend on changes in concentrations.

Given Data / Assumptions:

• We need a definition that covers both exergonic and endergonic processes.
• Conditions are standard biochemical contexts (constant T, P).
• ΔG can be positive, negative, or zero.

Concept / Approach:
ΔG < 0 means energy is released (exergonic), ΔG > 0 means energy is required (endergonic), and ΔG = 0 indicates equilibrium. Thus, ΔG is the energy liberated or taken up as a reaction proceeds at the specified conditions and concentrations.

Step-by-Step Solution:

Verification / Alternative check:
Biochemical thermodynamics texts define ΔG comprehensively to encompass both directions; this validates choosing the combined statement.

Why Other Options Are Wrong:

• “Liberated” only or “taken up” only each describes just one sign of ΔG.
• “None of these” is incorrect because a correct description is present.

Common Pitfalls:
Equating ΔG with ΔH (enthalpy). ΔG also reflects entropy contributions and concentration effects (via RT ln Q).

Final Answer:
liberated or taken up during reaction