Final answer:
Reversible reactions in a cell rarely reach equilibrium because the concentrations of reactants and products are in a constant state of flux within the open, dynamic system of a living cell.
Step-by-step explanation:
A student has asked why reversible reactions in a cell rarely reach equilibrium. The answer to this question is that reversible reactions in a cell rarely reach equilibrium because concentrations of reactants and products constantly change in a living cell. This continuous change is due to the fact that cells are open systems where materials can pass in and out, and the cell can recycle products of certain reactions into other reactions. This dynamic system is essential for life because if a cell were to reach chemical equilibrium, it would not have the free energy necessary to maintain life processes. Energy is continuously required to drive reactions in the direction needed to sustain life, and this energy often comes from nutrients produced by photosynthesis, which relies on sunlight. In essence, living organisms continuously engage in an energy-demanding battle against reaching equilibrium and entropy, ensuring that equilibrium in cellular reactions is never attained.