Research Ethics

As I am doing a fairly straightforward research paper, I doubt that I will have much trouble meeting the guidelines mentioned in the Belmont report. The main thing that all research papers have to be aware of is of course the risk of accidental plagarism, ex inadequately quoting sources, misquoting, mistakenly hijacking another person's theoretical concept. It all seems rather overwhelming at times for this simple undergraduate student! As ideas have been circulating through humanity for eons, it is hard to be original and at the same time be stringently attentive to who you are quoting from or whose idea you may be altering. For example, when writing a comparative politics essay relating the nation-building process of Iran and Turkey, one will undoubtedly use observations that someone else MUST have published at some point, like the fact that the two nations' are almost ideological opposites in the way they think government should be run (secular vs theocracy). In in instance like that, which is basically stating the obvious, do you still have to quote a source? Is it possible to discover a source, or is there a point where some observations go beyond intellectual copyright and are simply part of the public domain of knowledge? Any thoughts on that perhaps?