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The Science of Biology
Biology is frequently described as the scientific study of living things, but it is often taught as a collection of facts about organisms. Science is a dynamic process, constantly evolving as new technologies and new information become available. In this chapter, and throughout the book, we will emphasize the process of science that leads to our current understanding of the structure, function, interrelationships, and evolution of living things.
Biology as Science
Biology, which began as a descriptive science, is based on testable hypotheses and predictions, as are the other sciences such as physics and chemistry.
The Nature of Science
Science is a process, a way of knowing about the natural world. Natural phenomena have natural causes that can be discovered by observation and explained by forming and testing hypotheses. Scientific understanding of the natural world is dynamic. It continually changes, becoming richer, as we gain new insights or invent new tools to study natural processes.
Two Approaches to Scientific Study
Inductive reasoning (induction) is a discovery process that uses specific observations to construct general principles. If every living thing we examine microscopically is composed of cells, we can induce the general principle that all living things are composed of cells even though we haven't looked at all living things. If we accept the general principle that living things are composed of cells and observe a fossil with cellular structure, we can deduce (deduction) that the fossil was once alive.
A hypothesis is a tentative explanation for an observation or a prediction of what will occur. Both inductive and deductive reasoning can give rise to testable hypotheses. Scientific experiments are carefully designed to test specific hypotheses. Hypotheses are accepted if they are supported by testing, but rejected if the data are inconsistent with the predicted results.
In science an explanation that is broad in scope and well supported by a large body of evidence is called a theory. Scientific theories generate new hypotheses that drive discovery, and there is always the possibility that new discoveries will force us to modify or even reject our current theories. Note that this definition is virtually the opposite of the common usage of the term theory.
Biology and Life
Life, which seems like such an obvious concept, is impossible to define precisely because of the great variety of living things.
The Properties of Life
Life defies simple definition, but there are a number of properties that, if taken together, describe the characteristics of living things. Among these are cellular organization, ability to grow (increase in size; increase in cell number; and/or develop specialized cells, tissues, and organs), reproductive capability, responsiveness to stimuli, utilization of chemical energy, homeostasis (ability to self-maintain the living condition), and ability to evolve.
Cells are composed of subcellular units, various organelles within a protoplasmic matrix, that themselves are not alive. These, in turn, are constructed from atoms and molecules. Many organisms are unicellular, but multicellular organisms are composed of specialized cells organized into tissues, organs, and organ systems. Different organisms interact with each other at different levels in their environment: with other organisms of the same species in populations; with other species in communities; and with the physical environment in ecosystems.
At each higher level in the hierarchy of life, novel properties emerge that could not be predicted based on the properties of the lower levels. These emergent properties are the result of the arrangement of parts and interactions between them as complexity increases. For example, chlorophyll molecules can absorb light energy but it is simply released as fluorescent light of lower energy. If the same molecules are embedded in chioroplast membranes, the same light energy can be converted into the chemical energy of ATP and NADPH that is used to synthesize sugar from CO2College Biology. Copyright © by Marshall Sundberg. Reprinted by permission of HarperCollins Publishers, Inc. All rights reserved. Available now wherever books are sold.