what is biology?

The Science of Biology Chapter 1 * What is Biology? Bio = Life and logy = Study of The study of life using the scientific method * Properties of Life Living organisms: are composed of cells (cell theory) are complex and ordered (hierarchical organization) respond to their environment (irritability) can grow and reproduce (very important) obtain and use energy (metabolism) maintain internal balance (homeostasis) allow for evolutionary adaptation (?) * * Levels of Organization Cellular Organization cells organelles molecules atoms The cell is the basic unit of life. * Levels of Organization Organismal Level organism organ systems organs tissues * Levels of Organization Population Level ecosystem community species population The Nature of Science Science aims to understand the natural world through observation and reasoning. Science begins with observations, therefore, much of science is purely descriptive. Science uses both deductive and inductive reasoning * Deductive and Inductive Reasoning Deductive reasoning uses general principles to make specific predictions. Inductive reasoning uses specific observations to develop general conclusions. * The Scientific Method Scientists use a systematic approach to gain understanding of the natural world: -Observation -Hypothesis formation -Prediction -Experimentation -Conclusion Scientist use the Scientific Method with the following steps: Observation Hypothesis Theory Law * Question Tests & Exp. Tests & Exp. Hypothesis A hypothesis is a possible explanation for an observation. A hypothesis -must be tested to determine its validity -is often tested in many different ways -allows for predictions to be made * The Experiment -is a controlled recreation of a natural event -tests the hypothesis -must be designed to test only one variable at a time -consists of a test experiment and a control experiment * Scientific Theory and Law A scientific theory -is a body of interconnected concepts -is supported by much experimental evidence and scientific reasoning -expresses ideas of which we are most certain A scientific Law: The highest level of stating scientific information * Charles Darwin Served as naturalist on mapping expedition around coastal South America. Used many observations to develop his ideas Proposed that evolution occurs by natural selection * * Voyage of the Beagle Evolution and Natural Selection Evolution: Change through time. -“descent with modification” Natural Selection: individuals with superior physical or behavioral characteristics are more likely to survive and reproduce than those without such characteristics * * Darwin’s Evidence Similarity of related species - Darwin noticed variations in related species living in different locations * Darwin’s Evidence Population growth vs. Availability of Resources -population growth is geometric -increase in food supply is arithmetic Darwin based his ideas on the writings of Thomas Malthus. Post-Darwin Evolution Evidence Fossil record - New fossils are found all the time - Earth is older than previously believed Mechanisms of heredity - Early criticism of Darwin’s ideas were resolved by Mendel’s theories for genetic inheritance. * * Post-Darwin Evolution Evidence Comparative anatomy - Homologous structures have same evolutionary origin, but different structure and function. - Analogous structures have similar structure and function, but different evolutionary origin. * Post-Darwin Evolution Evidence Molecular Evidence - Our increased understanding of DNA and protein structures has led to the development of more accurate phylogenetic trees. Unifying Themes in Biology Cell theory - All living organisms are made of cells, and all living cells come from preexisting cells. Molecular basis of inheritance DNA encodes genes which control living organisms and are passed from one generation to the next. Structure and Function -Form follows function. * Unifying Themes in Biology (Cont.) Evolutionary change - Living organisms have evolved from the same origin event. The diversity of life is the result of evolutionary change. Evolutionary conservation - Critical characteristics of early organisms are preserved and passed on to future generations. * Unifying Themes in Biology (Cont.) Cells - information processing systems - Cells process information stored in DNA as well as information received from the environment. Emergent properties - New properties are present at one level of organization that are not seen in the previous level. * * * Learn the cell Evolution Chart