Do you know [what time the bank opens]?
 [What time the bank opens] is an interesting question.
In both examples, the bracketed constituent is a subordinate interrogative clause (embedded question).
It matters not whether the embedded question is complement of a verb, as in , or subject of the sentence. In both constructions there should be no inversion.
The meaning of  is:
"Do you know the answer to the question 'What time does the bank open?'"
And the meaning of  is:
"The answer to the question 'What time does the bank open?' is an