An assessment in which a student fills in words or phrases that have been systematically omitted from a text is called a

It's called a Cloze test, or Cloze Deletion test - an exercise or test where a person is asked to work out the missing piece of vocabulary.

This would be a true statement

An informal structure in a bureaucracy would be something like so-called "office politics". where there's a formal structure set up for the organization, but then an informal subculture as well that has a way of organizing the bureaucracy further. this can be positive because it sets up an added degree of organization, albeit informal, within the bureaucracy.