Question

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The fourth reaction of glycolysis is the aldol cleavage of fructose-1,6-bisphosphate (F-1,6-BP) to dihydroxyacetone phosphate (DHAP) and glyceraldehyde-3-phosphate (GAP): F-1,6-BP → DHAP + GAP What about this process suggests that the forward reaction can be expected to occur based on the second law of thermodynamics?
a. The process is characterized by a negative ΔH.
b. The reaction is endergonic.
c. The process results in an increase in entropy.
d. The process is at equilibrium.

Answer 1

Equilibrium in reactions occurs when the forward and reverse rates are equal, while a steady state maintains constant reactant and product levels without equilibrium. Endergonic reactions absorb energy and can be spontaneous if coupled with a larger exergonic reaction.

Step-by-step explanation:

To distinguish between the equilibrium and steady-state of reactions, it's essential to understand that equilibrium refers to a condition where the rates of the forward and reverse reactions are equal, and no net change is observed over time. In contrast, a steady state is achieved in an open system where the concentration of reactants and products remains constant due to continuous input and output, even though the forward and reverse reactions do not necessarily have to be at equal rates.

An endergonic reaction is one where free energy is absorbed, and as such, these reactions are typically non-spontaneous under standard conditions. However, an endergonic reaction can become spontaneous if it is coupled with a second, exergonic reaction that releases a larger amount of free5 energy. The net free energy for the coupled reactions would then be negative, allowing the endergonic process to proceed spontaneously. This coupling mechanism is a cornerstone in biochemical processes, including photosynthesis and cellular respiration.