Which part of an enzyme molecule binds to its associated substrate?

The part of the enzyme molecule that binds to its associated substrate is ACTIVE SITE.
The active site contains the catalytic groups which are amino acids which promote the formation and the break down of bonds. By breaking and forming new bonds, the enzyme substrate interaction brings about the formation of the transition state.

The mushroom population will decrease.

Explanation:

The animals introduced into the forest will likely eat the mushrooms.