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Unformatted text preview: Survey of the Survey of the biological world
Sci 103 Fig. 1-8c(10), p.9 Biology Biology Scientific study of life Lays the foundation for asking basic questions about life and the natural world Why Study Biology? Why Study Biology? To learn how organisms are constructed, how they function, where they live, and what they do To help develop, modify, and refine ideas about life WHAT IS LIFE WHAT IS LIFE
What does all living things have in common with each other? Unity of Life Unity of Life
All organisms: Are composed of the same substances Engage in metabolism Sense and respond to the environment Have the capacity to reproduce based on instructions in DNA Molecules of Life Molecules of Life All things are made up of the same units of matter Living things are made up of a certain subset of molecules:
Nucleic acids Proteins Carbohydrates Lipids Nothing Lives without Energy Nothing Lives without Energy
Energy = Capacity to do work Metabolism = Reactions by which cells acquire and use energy to grow, survive, and reproduce Energy Flow Energy Flow Usually starts with energy from sun Transfer from one organism to another Energy flows in one direction Eventually, all energy flows back to the environment energy input, from sun Producers
(plants, and other selffeeding organisms) Nutrient Cycling Consumers
Animals, most fungi, many protists, many bacteria energy output (mainly metabolic heat)
Fig. 1.3, p.6 Sensing and Responding Sensing and Responding Organisms sense changes in their environment and make responses to them Receptors detect specific forms of energy (stimuli) Allows maintenance of homeostasis DNA (deoxyribonucleic acid) DNA (deoxyribonucleic acid) Signature molecule of life Molecule of inheritance Directs assembly of amino acids Stepped Art
Fig. 1-5, p.7 DNA and Inheritance DNA and Inheritance Inheritance Acquisition of traits by way of transmission of DNA from parent to offspring Reproduction Mechanism by which an organism produces offspring Governed by instructions in DNA Mutation: Source of Variation Mutation: Source of Variation Mutation = change in structure of DNA Basis for the variation in heritable traits Most are harmful Evolution Evolution Genetically based change in a line of descent over time Leads to diversity QUESTIONS ABOUT THE QUESTIONS ABOUT THE DIVERSITY OF LIFE How to deal with the multitudes of diversity Where did the diversity of organisms come from? Is life still changing today? Diversity of Life Diversity of Life Millions of living species Millions more now extinct Classification schemes attempt to organize diversity Levels of Organization Levels of Organization
Cell Multicelled Organism Population Community Ecosystem Biosphere LEVELS OF ORGANIZATION LEVELS OF ORGANIZATION Levels of Organization Levels of Organization Fig. 1.2, p.5 Scientific Method Scientific Method Observe phenomenon Question Develop hypotheses Make predictions Devise test of predictions Carry out test and analyze results Inductive Logic Inductive Logic Using observations and facts to arrive at generalizations or hypotheses Observation: Eagles, swallows, and robins have feathers Hypothesis: All birds have feathers Deductive Logic Deductive Logic Drawing a specific conclusion based on a generalization Generalization Birds have feathers Example Eagles are birds Conclusion Eagles have feathers Experimental Design Experimental Design Control group A standard for comparison Identical to experimental group except for variable being studied Nonrepresentative sample skews results Minimize by using large samples Sampling error Role of Experiments Role of Experiments Used to study a phenomenon under known conditions Allows you to predict what will happen if a hypothesis is not wrong Can never prove a hypothesis 100% correct Scientific Theory Scientific Theory A hypothesis that has been tested for its predictive power many times and has not yet been found incorrect Has wideranging explanatory power Darwin’s theory of evolution by natural selection Limits of Science Limits of Science Scientific approach cannot provide answers to subjective questions Cannot provide moral, aesthetic, or philosophical standards Conflict with supernatural beliefs Copernicus Darwin Scientists Raise Questions Scientists Raise Questions
The external world, not internal conviction, must be the testing ground for scientific beliefs ...
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- Fall '09