Just like a food chain, energy enters the food web at the trophic level of the producers, which can also be called autotrophs. In the desert, autotrophs are often some type of cactus, grass, or shrub.
The main purpose of the INTRODUCTION is to give a description of the problem that will be addressed. In this section the researcher might discuss the nature of the research, the purpose of the research, the significance of the research problem, and the research question(s) to be addressed. Three essential parts of a good introduction are: RATIONALE.
The introduction is the beginning of an essay. It does the same job for an essay as the topic sentence does for a paragraph. In a paragraph, the topic sentence tells the reader what the subject of the paragraph will be and how it will be developed. In an essay, the introduction, which can be one or two paragraphs, introduces the topic. There are three parts to an introduction: the opening statement, the supporting sentences, and the introductory topic sentence. There are many ways to write an introduction, but it is necessary to include each of the three parts: