Question 2 The arrows in the diagram show continuous, cyclic movements from one subsystem to another without an end. Reflect
upon your previous answers and knowledge of Earth's subsystems to determine whether the arrows in the diagram best
represent matter, energy, or both. Explain your answer and provide at least one example that occurred during the
Precambrian era.

try using substitution:

x + y - 6 = x - y. (i'm not giving you the exact answer). since 0 = x - y, then sub 0 in the equation with x - y. combine your like terms, and then use inverse operations, and you'll have your answer.

: -)

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