What is the relationship between exergonic reactions, endergonic reactions and the use and regeneration of ATP?

Regeneration of ATP is an endergonic reaction and is coupled with an exergonic reaction.

ATP hydrolysis is an exergonic reaction and provides energy for other endergonic reactions.

Explanation:

Phosphorylation of ADP into ATP is an endergonic reaction while ATP hydrolysis into ADP and inorganic phosphate is an exergonic reaction.

The exergonic reactions are the ones that release energy. The released energy can drive the endergonic phosphorylation of ADP into ATP.

The endergonic reactions are the ones that need the input of energy to occur. These reactions are often coupled with ATP hydrolysis as ATP hydrolysis releases energy.

Therefore, endergonic reactions use ATPs while exergonic reactions release energy to regenerate ATPs.