What happens at the active site of an enzyme? a Many different types of reactants are bound
b Reactants and products are bound tightly and
specifically
C Both reactants are bound tightly and specifically
d
Many reactants and products are bound
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In biology, the active site is the region of an enzyme where substrate molecules bind and undergo a chemical reaction. The active site consists of amino acid residues that form temporary bonds with the substrate (binding site) and residues that catalyze a reaction of that substrate (catalytic site).

B, but its my opinion.

the answer is d p: cell, q: organ, r: organ system, s: tissue