A Big-Billed Bird Rebounds
Introduction to class content and course organization.
Introductory comments about the science of biology.
Core themes in biology.
How do biologists organize their subject matter?
Biology is a broad collection of subdisciplines such as evolution, ecology, zoology, cell
biology, and genetics.
Can we uncover some common concepts that underlie all biological study?
Evolution is the unifying theory of biology. All living organisms are composed of cells,
which are the basic units of life. All life forms are related and use DNA and RNA. The
genetic code is virtually universal. Biological study unifies the concepts of structure and
NOTE: As a preface to your review of the themes and characteristics of life, ask your
students what they hope to get from the course, and discuss how the material to be covered in
the course is relevant to their lives.
To begin, we start our study of biology by focusing on the relationship between the brown
pelican, the fish they eat, and the humans with whom the brown pelican must compete for space
I. The Scope of Biology
Life’s levels of organization define the scope of biology.
The levels at which life is organized are (from most to least inclusive): biosphere, ecosystem,
community, population, organism, organ system, organs, tissues, cell, organelles, and molecules
NOTE: Ask your students for examples, other than those in Figure 1.1, of each level of
organization. Distinguish between unicellular and multicellular organisms.
These levels represent a hierarchy because each level is built of parts at successively lower
levels of organization.
Biological researchers investigate the full spectrum of life, from the biosphere to the
biochemical reactions within a cell.
Preview: The dynamics of higher levels of organization are discussed in Chapters 36
(populations) and 37 (communities and ecosystems).
Living organisms and their environments form interconnecting webs.
Living things do not exist in isolation from their environment. An organism’s environment
includes both living and nonliving components.