Where does a substrate enter on an enzyme? once the substrate does enter, we call it an substrate (fill in the word before and after the word “substrate”) sorry im really confuse on this question

How did alexander fleming’s research solve a societal problem? he developed ways to treat inherited diseases. he advocated for regular hand washing to kill germs. he discovered a new type of medicine that could treat infections. he discovered the cause of mad cow disease, an emerging disease.