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Transcript
Concepts & Methods in Biology Chapter 1 Biology Scientific study of life Lays the foundation for asking basic questions about life and the natural world 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 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 DNA (deoxyribonucleic acid) Signature molecule of life Molecule of inheritance Directs assembly of amino acids 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 DNA Guides Development Multicelled organisms develop Series of stages Instructions for each stage in DNA Nothing Lives without Energy Energy = Capacity to do work Metabolism = Reactions by which cells acquire and use energy to grow, survive, and reproduce 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 Levels of Organization Cell Multicelled Organism Population Community Ecosystem Biosphere Interdependencies among Organisms Producers Make their own food Consumers Depend on energy stored in tissues producers Decomposers Break down remains and wastes of 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 FROM SUN Producers NUTRIENT CYCLING Consumers, Decomposers ONE-WAY FLOW OF ENERGY In time, all energy flows back to the environment. Unity of Life All organisms: Are composed of the same substances Engage Sense Have in metabolism and respond to the environment the capacity to reproduce based on instructions in DNA Diversity of Life Millions of living species Millions more now extinct Classification schemes attempt to organize diversity Scientific Names Devised by Carolus Linnaeus First name is genus (plural, genera) Homo sapiens - genus is Homo Second name is species within genus 3 Domains Eubacteria (Bacteria) Archaebacteria (Archaea) Eukaryota (Eukaryotes) 6 Kingdoms Protistans Plants Fungi Animals Eukaryotes Archaebacteria Eubacteria Origin of life Prokaryotic Organisms Eukaryotic Organisms Single cells Single- or multi-celled No nucleus or Nucleus and other organelles Smaller, less complex organelles Larger, more complex Mutation: Source of Variation Mutation = change in structure of DNA Basis for the variation in heritable traits Most are harmful Adaptive Trait A trait that gives the individual an advantage in survival or reproduction, under a given set of circumstances Evolution Genetically based change in a line of descent over time Population changes, not individuals Artificial Selection Breeders are selective agents Individuals exhibiting favored traits are bred Favored traits become more common in population Natural Selection Individuals vary in some heritable traits Some forms of heritable traits are more adaptive Natural selection is differences in survival and reproduction among individuals that vary in their traits Adaptive forms of traits become more common than other forms Antibiotic Resistance Antibiotics are used to kill bacteria Mutations for antibiotic resistance exist or arise Antibiotic-resistant bacteria survive and reproduce better than nonresistant Over time, proportion of antibiotic-resistant bacteria increases Scientific Method Observe phenomenon Develop hypotheses Make predictions Devise test of predictions Carry out test and analyze results 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 Drawing a specific conclusion based on a generalization Generalization - Birds have feathers Example - Eagles are birds Conclusion - Eagles have feathers 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 Experimental Design Control group A standard for comparison Identical to experimental group except for variable being studied Sampling error Nonrepresentative sample skews results Minimize by using large samples Scientific Theory A hypothesis that has been tested for its predictive power many times and has not yet been found incorrect Has wide-ranging explanatory power Darwin’s theory of evolution by natural selection 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 The external world, not internal conviction, must be the testing ground for scientific beliefs