act upon vs alter

act upon

verb
  • To take action on the basis of information received or deduced. 

alter

noun
  • An identity or headmate of a person with dissociative identity disorder (previously known as multiple personality disorder). A member of a system. 

verb
  • To castrate, neuter or spay (a dog or other animal). 

  • To change the form or structure of. 

  • To tailor clothes to make them fit. 

  • To become different. 

  • To affect mentally, as by psychotropic drugs or illness. 

How often have the words act upon and alter occurred in a corpus of books? (source: Google Ngram Viewer )