Invitation to Biology

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Invitation to Biology

• Biology 1030
• Principles of Biology

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Lifes Levels of Organization

• The world of life shows levels of organization,
  from the simple to the complex, which extend
  through
• Atoms ? Molecules ? Cells
• ? Tissues ? Organs ? Organ Systems ? Organism ?
• Populations ? Communities ? Ecosystems ? The
  Biosphere

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Molecules of Life

• All things are made up of the same units of
  matter
• atoms, molecules
• Living things are made of up of a certain subset
  of molecules
• nucleic acids, proteins, carbohydrates, lipids

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DNA (deoxyribonucleic acid)

• The signature molecule of life
• Molecule of inheritance
• Directs assembly of amino acids

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Heritability of DNA

• Inheritance
• Acquisition of traits by way of transmission of
  DNA from parent to offspring
• Reproduction
• Mechanisms by which an organism produces
  offspring
• Governed by instructions in DNA

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DNA Guides Development

• Development
• Transformation from fertilized egg to adult
• Series of stages
• Instructions for each stage in DNA

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Energy Is the Basis of Metabolism

• Energy Capacity to do work
• Metabolism Reactions by which cells acquire
  and use energy to grow, survive, and reproduce

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Interdependencies among Organisms

• Producers
• Make their own food
• Consumers
• Depend on energy stored in tissues of
  producers
• Decomposers
• Break down remains and wastes

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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

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Sensing and Responding

• Organisms sense changes in their environment and
  make responses to them
• Receptors detect specific forms of energy
• The form of energy detected by a receptor is a
  stimulus

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Homeostasis

• Maintenance of internal environment within range
  suitable for cell activities
• Pancreas maintains level of sugar in blood by
  secreting hormones

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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

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Diversity of Life

• Millions of living species
• Additional millions of species now extinct
• Classification scheme attempts to organize this
  diversity

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Scientific Names(Binomial Nomenclature)

• Two-part naming system devised by Carolus
  Linnaeus
• First name is genus (plural, genera)
• Homo sapiens - genus is Homo
• Second name is species within genus

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Three-Domain Classification

• Bacteria
• Archaea
• Eukarya (includes protists, plants, fungi, and
  animals)

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Classification of Living OrganismsHierarchy of
Classification

• Domain -Eukarya -Eukaryotic
• Kingdom -Animalia -Animal
• Phylum -Chordata -Spinal cord
• Class -Mammalia -Suckle young
• Order -Primates -Highly dev.
• Family -Hominoidae -Two-legged
• Genus -Homo -Human
• Species -sapiens -Modern human

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Lifes Diversity
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Prokaryotes

• Archaea and Bacteria
• Single-celled
• No nucleus or organelles
• Include producers, consumers, decomposers

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Eukaryotes

• Eukarya (plants, fungi, animals, protists)
• DNA is inside a nucleus
• Most are larger and more complex than the
  prokaryotes

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Plants

• All are multicelled
• Most are photosynthetic producers
• Make up the food base for communities, especially
  on land

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Fungi

• Most are multicelled
• Consumers and decomposers
• Extracellular digestion and absorption

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Animals

• Multicelled consumers
• Herbivores
• Carnivores
• Parasites
• Scavengers
• Move about during at least some stage of their
  life

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Mutation Source of Variation

• Mutation change in structure of DNA
• Basis for the variation in heritable traits
• Most are harmful

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Adaptive Trait

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

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Evolution

• Genetically based change in a line of descent
  over time
• Population changes, not individuals

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Natural Selection

• The outcome of differences in survival and
  reproduction among individuals that vary in
  details of heritable traits
• This process helps explain evolution - changes in
  a line of descent over generations

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Artificial Selection

• Breeders favor some form of traits over others
• Individuals exhibiting favored traits are bred
• Favored traits increase in the population

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The Scientific Method

• 1. Observe phenomenon (question)
• 2. Develop hypothesis (educated guess)
• 3. Experiments (tests)
• 4. Results (data)
• 5. Conclusions (support or reject hypothesis)
• Theory formed with high confidence

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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
• Darwins Theory of Evolution by Natural Selection

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Role of Experiments

• Procedures 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

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Experimental Design

• Control group
• A standard for comparison
• Identical to experimental group except for
  variable being studied
• Sampling error
• Non-representative sample skews results
• Minimize by using large samples

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Scientific experimentation involves the use of
variables

• 1. Independent variable variable that is
  manipulated
• 2. Dependent variable variable that is measured
• 3. Control variables variables that are held
  constant to insure that they dont impact the
  results (a reference)
• 4. Confounding variables variables that are
  neglected or uncontrolled that impact the results

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Field Experiment
Experimental Group 46 H. cydno individuals with
white markings
Control Group 34 H. cydno individuals with
yellow markings

• Study of Heliconius butterflies

Experiment Both yellow and white forms of H.
cydno butterflies are introduced into
isolated rain forest habitat of yellow H.
eleuchia butterflies. Numbers of
individuals resighted recorded on a daily basis
for two weeks.
Results Experimental group (H.
cydno individuals without yellow wing markings)
is selected against. 37 of the original group of
46 white butterflies disappear (80), compared
with 20 of the 34 yellow controls (58).
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Limits of Science

• Science is never absolute and is based solely on
  empirical evidence
• Scientific approach cannot provide answers to
  subjective questions
• Cannot provide moral, aesthetic, or philosophical
  standards

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Science and the Supernatural

• Science has run up against religious belief
  systems
• Copernicus suggested that sun, not the Earth, was
  center of universe
• Darwin suggested that life was shaped by
  evolution, not a single creation event

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Asking Questions

• Scientists still ask questions that challenge
  widely held beliefs
• The external world, not internal conviction, is
  the testing ground for scientific beliefs