Biology is a broad field and biologists ask questions at a multiplicity of levels, ranging from the sub-molecular to the biospheric. However, to understand the intellectual structure of biology it is important to realize the implications of a hierarchy. Each level of organization incorporates most of the levels below it, and contributes to several of the levels above it. For instance, ecological interactions are often the result of physiological specializations that are the consequences of specific cellular organizations. Similarly, one of the most powerful approaches to understanding evolutionary relations among organisms is to use DNA sequence analysis, a technique originally developed to answer questions in molecular genetics.
Biology is also an interdisciplinary subject.
Elements of mathematics, chemistry, and physics are essential for an understanding of life processes and as investigative tools. Also, biology is an important component of other disciplines, ranging from medicine, psychology, and anthropology to geology, oceanography, and applied engineering. Thus, the study of biology offers a very wide range of possibilities for intellectual development, but at the same time demands substantial training in other sciences. The biology major provides an excellent foundation for advanced study at the graduate level, for a wide array of career opportunities, and for further training in many areas. These include medicine, biomedical sciences and other health-related professions, biotechnology, environmental science, law, biomedical ethics, education, journalism, and public health.