Three Laws of Thermodynamics

Metabolism is the totality of an organism’s chemical processes.

1st Law: Conservation of mass - energy

Energy can neither be created or destroyed

According to all equations of chemical reaction, both sides are balanced. The amount of energy for the entire universe is constant.

2nd Law: Law of Entropy

All spontaneous events act to increase total entropy

The states of all spontaneous reactions would become more random a.k.a. the increase of entropy. The number of molecules of the reaction would change from less to more. Free energy would form during the exergonic reaction (it is a spontaneous reaction)

If a reaction changes to more organized form, there must be external energy used on the reaction.

3rd Law: Absolute Zero (0 K = -273℃)

All thermal molecular motion, kinetic energy ceases

When an object reaches the absolute zero in theory, because it is possible to approach absolute zero but never reach to it. This moment will be the removal of all thermal molecular motion. No motion would continue going, everything stops.  

Second law of thermodynamic and metabolism

Living organisms seem obey the second law of thermodynamics, but actually, nothing could obey this law which all spontaneous events act to increase total entropy. Metabolism for living organism is not really spontaneous. It still requires external energy to begin the job. Energy receive from daily diets would transfer enough energy for living organisms to survive. When living organism absorbs these energy, the entropy for the entire universe is increased.

The confusion of the second law is always on “define the spontaneous reaction” and “what is the entire system when talking about total entropy increase”.