Wrting a scientific paper is a science, we have to publish our work
Scientific and technical writing can almost never be 'general purpose'; it must be written for a specific audience. For the kinds of writing addressed here, that audience will generally be the community of ecologists who read a particular journal or study a particular subject. This community is represented by your professor for class papers. In all cases, you must adopt the style and level of writing that is appropriate for your audience. Stylistic conventions and acceptable jargon can vary tremendously from one field to another, and to some extent, from one journal to another.