What is the term that refers to this evolutionary relationship?

Phylogenetics

Explanation:

An evolutionary tree can also be called a phylogenetic tree, or a just a phylogeny, and phylogenetics is the study of determining evolutionary relationships, or patterns of descent of organisms.

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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