Answer:
enzymes are biological catalysis in the body which means they speed up chemical reactions without being used up in the process.
the main concept is the lock and key theory ,every enzyme has an active site which has a unique shape for a specific substrate.Enzymes can only catalyse one specific reaction
for an enzyme to work the substrate has to fit into the active site and if it doesn't fit the active site the reaction will not take place.,the active site may change shape a little as the substrate binds to it to get a tighter fit, this is called an induced fit.