Each enzyme only has 1 substrate that will fit its active site what is it called

Enzyme specificity or specific

Explanation:

Enzymes are highly specific to substrates as they have an active site which only allow certain substrates to bind to the active site. This is due to the shape of the active site and any other substrates cannot bind to the active site.

there is a model which is well known in the biology field of the lock and key model. this is because you have to have the correct key to insert it into the lock. this goes the same as an enzymes active site and the substrate.