If the cell could no longer produce vesicles, nothing could be transported around inside, including proteins being made and moved to Golgi or out of the cell. No protein would be secreted. B. Enzymes interact very specifically with their substrates, or what they start the reaction with. There can be more than one substrate, or more than one product. Typically, regradless of the numebr of substrates for a given reaction, enzymes are only specific for one reaction in the cell.
Different enzymes perform different reactions.