Biology is defined as the "study of life." The term life refers to all organisms (plants, animals, bacteria, fungi, and protists) inhabiting Earth and its atmosphere. Both scientists and laypeople are drawn to biology because it seeks to answer the question of how life began. All of the acquired evidence points to a single origin for all living things.

The study of evolution shows that there are significant similarities among organisms that are not obviously related. Virtually every organism uses the same genetic code to builds its proteins , from the tiniest bacterium to the blue whale and the giant sequoia. A fungus and a horse break down sugar to release energy using (more or less) the same enzymes . Indeed, evolution, the gradual change in a population over time, serves as a unifying concept in biology.

The more related two species of multicellular organisms are, the more similar their anatomies in almost all cases. Species that rely heavily on one another for life evolve in response to each other's habits and characteristics. Researchers use animals closely related to humans in order to predict the effects of new drugs or surgical techniques on human subjects, taking advantage of evolutionary relationships that yield similar anatomies and physiologies in different organisms.

Biology's Subdisciplines

Biology encompasses many diverse subdisciplines. Systematics is the study of the diversity and classification of organisms. Cell biology is concerned with the structure and function of cells but also includes the interactions that occur between cells (for example, the signaling that occurs among different cells of the human body). The field of ecology considers interactions among organisms that inhabit the same area. For example, ecologists might study the changes in population size of a group of birds in response to the presence of a predator, or the impact of pollution on frog populations. Someone interested in medicine would need a solid background in anatomy, the study of the structure of the bodies of animals and how different components of the body relate to one another.

Physiology, which is closely related to anatomy, describes the mechanisms by which these different components perform. One might also study the anatomy and physiology of plants to learn how different tissues within a plant perform and interact. Microbiology, a field driven largely by the study of disease, is concerned with the structure, function, and interactions of microorganisms. Genetics is concerned with the inheritance of characteristics from parents to offspring, and the expression of genes to create the living organism.

Much emphasis in biology is in biotechnology, the use of organisms to create products. This field opens unimaginable possibilities for the diagnosis and treatment of hereditary diseases, production of drugs, and advancement of agriculture. At the same time, these prospects will challenge scientists with serious ethical considerations in the years to come, as the use of biotechnology requires scientists to manipulate the course of evolution.

SEE ALSO Biodiversity ; Biotechnology ; Ecology ; Evolution

Karen Gunnison Ballen


Krogh, David. Biology: A Guide to the Natural World. Upper Saddle River, NJ: Prentice Hall, 2000.

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