Final answer:
In living cells, metabolic reactions occur predominantly in the forward direction due to the consumption of end products and expenditure of energy.
Step-by-step explanation:
Living cells constantly engage in metabolic reactions that involve the breaking down and building up of molecules. These reactions are reversible and can proceed in both forward and backward directions.
However, in living cells, the end products of metabolism are usually consumed and energy is spent, causing the metabolic reactions to occur predominantly in the forward direction. This is because living cells are open systems that require a continuous supply of energy to maintain their activities and counterbalance the natural tendency towards chemical equilibrium.