What binds to the active site of an enzyme?

Arrange the steps of the biochemical reaction in sequence:
$I -$ Diffusion of the substrate towards the active site of the enzyme
$II -$ Formation of the transition state structure
$III -$ Release of the product from the active site
$IV -$ Breaking or formation of bonds

Which class of enzymes catalyzes the covalent bonding of two substrates?

Enzymes which are slightly different in molecular structure but can perform identical activity are called

Enzyme arginase is found in

Enzymes were discovered for the first time in