There cannot be more carnivores than herbivores because the carnivores eat the herbivores. If there wasn't enough herbivores to eat, then the carnivores would eventually become extinct.
Mastication is just a fancy way to say chewing. Since nothing chemical is going on and the food is just being chewed, the answer is physical.
A chemical reaction bonding monomers together to make a polymer
For example, pH can have an effect of the state of ionization of acidic or basic amino acids. Acidic amino acids have carboxyl functional groups in their side chains. Basic amino acids have amine functional groups in their side chains. If the state of ionization of amino acids in a protein is altered then the ionic bonds that help to determine the 3-D shape of the protein can be altered. This can lead to altered protein recognition or an enzyme might become inactive.
Changes in pH may not only affect the shape of an enzyme but it may also change the shape or charge properties of the substrate so that either the substrate connot bind to the active site or it cannot undergo catalysis.
In geneal enzyme have a pH optimum. However the optimum is not the same for each enzyme.
I'm not sure what you mean by "compartments", but the cardiovascular system consists of the heart, blood vessels, and approximately 5 liters of blood.