The proposal serves a very distinctive topic of letting the board know that the applicant has put enough effort and time into preliminary research in their area of interest and know exactly what they can offer to the scientific community besides a generic description of a broad section of science.
There is no fixed guideline for writing a research proposal for one simple reason: over the course of the research the direction of the study can change multiple times, which makes it nearly impossible to predict the outcome of the research.
Background: Explain your interest in and experience with this topic.
Describe any previous research you have conducted on this or related topics, any classes you have taken on this or related topics, or any reading you have already done in the field.
[See drafting and revising the research paper for more on this aspect of the project.] NOTE: Each discipline and granting agency has its own guidelines for writing research proposals, so if you have been assigned to write one for a class other than a composition class, please consult your professor.
Statement of purpose: Explain what you hope your research will find or show.
A professor who is initially skeptical about a project may be able to imagine it more easily after reading a well written research proposal (this doesn't mean he or she will approve the topic, especially if there are significant potential difficulties that you haven't considered).
Once you have begun your research project, a research proposal can help you to remain on track -- and can also remind you why you started this project in the first place!
Researchers very often begin to lose heart about two thirds of the way into a project when their research hits a snag or when they are having problems developing a thesis, organizing the ideas, or actually starting to write.
Rereading the initial research proposal, especially "Significance" can re-energize the project or help the researcher to refocus in an effective manner.