Correct formatting of scientific literature plays a critical role in communication. It gives the reader the sense that the author pays attention to detail and gives authority to the science. There is no single approved style guide for source citation in the Biological Sciences--there is no APA style manual for them! See DEWC guide below for specific writing information.
For help with any and all stages of the writing process, including citing sources, you can visit the friendly people at the Debby Ellis Writing Center.
From pages 100-101 of the Southwestern University Student Handbook:
"Plagiarism is the submission of another’s work as one’s own without acknowledgment in written work. There are basically four ways in which research papers use or incorporate written materials, and each of these requires footnoting.
1. Direct Quotations should be marked off with quotation marks, with a footnote to indicate the source. It is not necessary to place in quotation marks every word in your paper that appears in a source you are using. If your paper concerns Napoleon, for example, you need not place “Napoleon” in quotation marks merely because your sources use the name. Similarly, there are phrases of some length such as “on the other hand” or “it is evident that” which are common property and act in effect as single words.
2. Paraphrase. Where your own language follows closely the language of a written source, or where your line of argument follows a source, you need not use quotation marks, but you are obliged to indicate the source in a footnote.
3. General Indebtedness. Where the ideas in your paper closely resemble and were suggested by ideas in a source, a footnote should be used to indicate this.
4. Background Information. In any area of inquiry there are matters of fact commonly known to everyone with a serious interest. Such information need not be footnoted one fact at a time. Instead, a general footnote toward the beginning of the paper, naming the sources where such information was obtained, is sufficient.