Secret questions

Just saw that Flickr requires me now to have 2 secret questions for password recovery needs. Among the proposed questions:

• name of favorite author
  
• name of favorite book
  
• name of favorite movie character
  
• etc
  

Are those answers supposed to be immutable ? Is my taste cast in stone ?

Update: one of my answers involved a 3 letters name, but Yahoo refused it as it isn't long enough.