Question

All biochemical pathways involve changes in free energy, and the graph below illustrates one type of free energy change between reactants and products in a chemical reaction.
Which statement is a correct interpretation of the graph?

• A. The reaction illustrated could represent cell respiration which is endergonic and the change in free energy is positive ($△G>0$).
• B. The reaction illustrated could represent cell respiration which is exergonic and the change in free energy is negative ($△G<0$).
• C. The reaction illustrated could represent the polymerization of glucose into glycogen which is endergonic and the change in free energy is positive ($△G>0$).
• D. The reaction illustrated could represent the polymerization of glucose into glycogen which is exergonic and the change in free energy is negative ($△G<0$).

Answer 1

The correct option is C The reaction illustrated could represent the polymerization of glucose into glycogen which is endergonic and the change in free energy is positive ($△G>0$).

In the given graph, as the reaction proceeds, the free energy of reaction is increasing

So we can conclude $△G>0$

When $△G>0$, then the reaction is endergonic i.e. heat is absorbed

Cell respiration releases energy so it is an exergonic reaction

Glycogen synthesis are endergonic i.e. glycogen synthesis requires the input of energy

So the reaction could represent the polymerization of glucose into glycogen which is endergonic and $△G>0$