A good example of a net endergonic process is photosynthesis.

There is more energy put into the system than comes out, so it's endergonic (not endothermic).

This, by itself may be endergonic but it is coupled with many other processes that can make the whole thing spontaneous.

So, an exothermic reaction can be either endergonic or exergonic.

The related concepts endergonic and exergonic apply to all physical processes.

Endergonic reaction reactions which are not spontaneous at standard temperature, pressure, and concentrations.

This is in contrast with an endergonic process.

The process of getting to the top of the activation energy to the transition state is endergonic.

Reactions that are driven beyond equilibrium by addition of free energy are called endergonic.

Many such reactions will link exergonic and endergonic processes.

An endergonic reaction is a chemical reaction that absorbs energy in the form of work.

As this occurs, energy is pumped from the exergonic partner into the products requiring endergonic synthesis.

Also, in metabolism, an endergonic process is anabolic, meaning, that energy is stored.

More generally, the terms exergonic and endergonic relate to the Gibbs free energy change in any process, not just chemical reactions.

Nevertheless, endergonic reactions are quite common in nature, especially in biochemistry and physiology.

The following endergonic equilibrium gives rise to the triiodide ion:

Metabolism is the total of all catabolic, exergonic, anabolic, endergonic reactions.

The first step is endergonic but it still happens because the second step is exergonic enough to make the whole process spontaneous.

The concentration of the products of the endergonic reaction thus always remains low, so the reaction can proceed.

Endergonic reactions can be pushed by coupling them to another reaction which is strongly exergonic, through a shared intermediate.

For Exergonic and Endergonic reactions, see the separate articles:

Endergonic reactions are not spontaneous.

Glycogen synthesis is, unlike its breakdown, endergonic.

Energy is required for glycogenesis, and the blood does not deliver energy, just the ingredients for endergonic reactions.

Endergonic reactions can be achieved if they are either pulled or pushed by an exergonic (stability increasing, negative change in Free Energy) process.