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The Science of Biology

1.1 Biology is the science of life.
Organization of Living Things
• All living organisms share a collection of characteristics: cellular organization, order, sensitivity, growth, development and reproduction, energy utilization, evolutionary adaptation, and homeostasis. (p. 2)
• The biological world is hierarchical from the cellular level to the population level, with emergent properties entering at each higher level. (p. 2)

1.2 Scientists form generalizations from observations.
The Nature of Science
• Deductive reasoning applies general principles to predict specific results, while inductive reasoning uses specific observations to construct general principles. (p. 4)
How Science Is Done
• Scientists make observations and then construct a suggested explanation (hypothesis) to account for those observations. (p. 5)
• A successful experiment rejects one or more alternative hypotheses. (p. 5)
• Often scientists will conduct two experiments in parallel. In one experiment, all the variables are kept constant except one, while in the other experiment, the control experiment, that variable is left unaltered. (p. 6)
• Predictions provide a way to test the validity of a hypothesis. (p. 6)
• A theory is a proposed explanation for some natural phenomenon, but the term is also used to refer to a body of interconnected concepts supported by scientific reasoning and experimental evidence. (p. 6)
• After developing a hypothesis and performing a series of experiments, a paper is written describing the experiment and the results; the paper is then submitted for peer review. (p. 7)

1.3 Darwin's theory of evolution illustrates how science works.
Charles Darwin
• In Darwin's time, most people believed species to be specially created and unchangeable. (p. 8)
• Darwin proposed the concept of natural selection to account for his view that living things must have changed during their history on earth. (p. 8)
• Darwin served as naturalist on a five-year navigational mapping expedition around the coasts of South America. (p. 8)
Darwin's Evidence
• Repeatedly, Darwin found that characteristics of similar species varied from place to place, suggesting that organismal lineages change gradually as species migrate, and that plants and animals on young volcanic islands resembled those on nearby coasts of South America. (p. 10)
Inventing the Hypothesis of Natural Selection
• Darwin was influenced by Thomas Malthus and his idea that plant and animal populations increase geometrically. (p. 11)
• Darwin reasoned that because only a limited number of offspring can survive in each generation, those possessing superior physical or behavioral attributes are more likely to survive. (p. 11)
• Darwin knew of extensive examples of artificial selection in domesticated animals, and he reasoned that such evolutionary change could also occur in nature. (p. 12)
Evolution After Darwin: More Evidence
• The increasingly complete fossil record, the determination that the earth is 4.5 billion years old, the discovery of heredity mechanisms, comparative anatomy studies differentiating homologous and analogous structures, and molecular evidence such as the discovery of molecular clocks all support Darwin's ideas. (pp. 13—14)

1.4 Four themes unify biology as a science.
Core Themes Unite Biology
• The four themes uniting the field of biology are the cell theory, the molecular basis of inheritance, evolutionary change, and evolutionary conservation. (pp. 15—16)

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