In which part of the digestive system does a chemical change of the food first occur? mouth esophagus stomach liver

The answer is: the mouth.

Explanation:

Chemical digestion is the breakdown of food into small particles to subsequently go through the process of absorption and transport to cells.

The mouth secretes enzymes capable of breaking relatively strong intra-molecular bonds so that difficult-to-digest molecules turn into small, digestible molecules (Nutrients).

well, that's easy; the answer's c, "it reduces contamination of the water and substrate of the estuary."

1. the energy lost to disorder metabolism     -entropy

2. related to or possessing motion potential     -kinetic

3. all of the chemical reactions in an organism required for maintenance of the processes of life entropy     -metabolism

4. possible; ability to go into action or perform work kinetic     -potential

5. the study of energy and its transformations thermodynamics     -thermodynamics