Choose the true statements referring to the following couple

Choose the true statement(s) referring to the following coupled reactions:

Rxn1

AB

DG°\' = -2 kJ/mol

Rxn2

BC

DG°\' = +7 kJ/mol

Rxn3

CD

DG°\' = -8 kJ/mol

Net Rxn

AD

DG°\' = -3 kJ/mol

Question 2 options:

Rxn1 is a favorable reaction and will proceed in cells even if cellular concentrations of reactants and products change.

Rxn2 (BC) is unfavorable in the forward direction on its own, but if coupled to Rxn3 (CD), the overall conversion of B to D will occur.

For Rxn2, if the DG°\' value changes to +9 kJ/mol, the rate of the overall reaction AD will decrease.

The net reaction of AD is unfavorable because the DG°\' value is less than 0.

Solution

The option second is true. In behavior reaction B ---C is unfavorable because it needs energy; it is depicted that the free energy is in positive form. But if the reaction is coupled with C---D then the reaction of B---C follow and the ultimate product D will occur. It is because B---C reaction needs 7KJ energy which can get from C---D ( -8KJ) and the net energy will be -1 KJ /mol.