Define the following types of fossils and give an example of an organism in one: Molds
Casts
Amber
Tar

answer; i believe that the correct answer is (lung);

enzyme active site and substrate specificity

enzymes bind with chemical reactants called substrates. there may be one or more substrates for each type of enzyme, depending on the particular chemical reaction. in some reactions, a single-reactant substrate is broken down into multiple products