Concepts & Methods in Biology Chapter 1

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 To understand issues of scientific research

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

Scientific Method Science is a Process Observation Research Question Hypothesis – Needs to be testable Experiment Results Conclusion

Role of Experiments Used to study a phenomenon under known conditions Allows you to predict what will happen as long as the hypothesis is not wrong

Experimental Design Control group Sampling error 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

Theory Vs. Scientific Law Theory is a hypothesis that has been supported by many lines of evidence A law is a theory that has been supported for a significant amount of time Can a theory ever be proven 100% correct?

Limits of Science Scientific approach cannot provide answers to subjective questions Cannot provide moral, aesthetic, or philosophical standards Can conflict with supernatural beliefs

What is Life? Organization Reproduction – life comes from life Growth and Development Metabolism Response to stimuli Homeostasis Adaptation

Hierarchy of Life Atoms – C,H,O,N = 96% of the dry weight Molecules – major organic compounds Cells – 2 cell types Tissues Organs Organ systems Organism Ecological order – population, community, ecosystem

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 Guides Development Multicelled organisms develop Instructions for each stage of development is 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 Photosynthesis and Cellular Respiration

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

Interdependencies among Organisms Producers – Autotrophs Make their own food Consumers – Heterotrophs Depend on energy stored in tissues of producers Decomposers Break down remains and wastes

Energy Flow Usually starts with energy from The Sun Transfered from one organism to another Energy flows in one direction Eventually, all energy flows back to the environment

Consumers, Decomposers 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 in metabolism Sense and respond to the environment Have 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: Binomial Nomenclature Carolus Linnaeus Binomial Nomenclature First name is genus (Capitalized) Homo sapiens - genus is Homo Second name is species within genus (Lower case) Always written either in italics or underlines

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- or multi-celled Nucleus and other organelles Larger, more complex Single cells No nucleus or membrane bound organelles Smaller, less complex

Mutation: Source of Variation a change in the structure of DNA Basis for the variation in heritable traits Most are harmful, beneficial ones may lead to evolution Point, Frameshift, and Chromosomal

Adaptive Trait A trait that gives the individual an advantage in survival or reproduction, under a given set of circumstances

Evolution Decent with modification 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