Audio Index: Slow dialog: 1:00 Explanations: 4:33 Fast dialog: 21:59 Comprehension: 24:01 We’ll continue our examination, then, of the, uh, branches of the science of biology. Biologists can specialize in and study many different things. But perhaps we should back up a bit and talk more generally about the study of nature in a larger context. The field of botany study plants—what kinds of plants, what their relationship is, and so forth. The field of zoology studies animals, and the discipline of anthropology is concerned with, well, us, human beings. But when we talk about biology, we usually think about the different levels of organization. We begin at the very lowest, or molecular level, which includes biochemistry and molecular genetics. We then proceed to the cellular level, but not one related to your phone! No, the cellular level refers to the cell as a component of an organism. A developmental biologist studies how that organism grows and changes over time. As we get higher up in complexity and scale, we begin to examine genetics and heredity, how the parent and the child or offspring are related and why. We can even study this notion of genetics in an entire population, what is known as population genetics. So, as you can see, biologists study many different aspects of organisms, and attempt to understand how they are related. There are no hard and fast rules about biological development, but our study is guided by certain, shall we say, underlying principles. This includes, for example, the principle of universality, the idea that all living things share certain properties. All of us, regardless of species, are carbon-based life forms. That’s one universal, true of all living things that we know of. Another is that organisms pass on some of their characteristics via some genetic material, and that there is a common mechanism for this. Another universal principle is that all organisms are comprised of cells…