Concepts and Methods in Biology

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Concepts and Methods in Biology

• Starr/Taggarts
• Biology
• The Unity and Diversity of Life, 9e
• Chapter 1

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Key Concepts

• There is unity and diversity in the world of life
• Theories of evolution and natural selection
  explain lifes diversity
• Biology is based on observations, hypotheses,
  prediction, and experimental tests

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DNA, Energy, and Life

• All organisms consist of one or more cells
• Cells arise only from pre-existing cells
• The signature molecule of cells is DNA
• DNA encodes protein-building instructions
• RNAs help carry out these instructions

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Objects Built from the Same Material but with
Different Instructions
DNA
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Nothing Lives Without Energy

• Energy The capacity to do work
• Everything has some amount of energy
• All events involve a transfer of energy
• Metabolism
• Capacity to obtain and convert energy from
  surroundings
• Capacity to use energy in maintenance and growth

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Sensing and Responding

• Receptors detect stimuli
• Stimuli are forms of energy
• Cells adjust metabolic activities in response to
  stimuli detected by receptors
• These responses maintain homeostasis
• Internal operating conditions remain within
  tolerable limits

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Levels of Biological Organization Hierarchy of
Organization
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Levels of Biological Organization Hierarchy
of Organization
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Interdependencies Among Organisms

• Producers
• Make their own food
• Consumers
• Depend on energy stored in tissues of producers
• Decomposers
• Break down molecules to simpler materials

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Energy Flow Materials Cycling
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Classification

• Species
• Genus
• Family
• Order
• Class
• Phylum
• Kingdom

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Six Kingdoms

• Fungi
• Multicelled
• Decomposers
• Eukaryotic
• Plantae
• Photosynthetic
• Eukaryotic
• Animalia
• Consumers
• Eukaryotic

• Archaebacteria
• Anaerobic cells
• Prokaryotic
• Eubacteria
• Bacteria
• Prokaryotic
• Protista
• Single and multicelled
• Eukaryotic

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An Evolutionary View of Diversity

• Mutation
• Molecular change in DNA
• Original source of variations in heritable traits
• May be harmful, harmless, or beneficial
• Adaptive trait
• Any trait that helps an organism survive and
  reproduce
• Whether a trait is adaptive or not depends on
  prevailing conditions

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Evolution

• Genetically based change in a line of descent
  over time
• Darwins theory of evolution by natural selection
  explains the connection between evolution and
  variation in traits

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Natural Selection

• Individuals in a population vary in some
  heritable traits
• Some heritable traits are more adaptive under
  prevailing conditions
• Differences in heritable traits influence
  survival and reproduction of individuals
• Adaptive traits become more common in population

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Biological Inquiry

• Observe nature
• Develop hypothesis
• Make testable prediction
• If tests do not confirm prediction, consider why
• Repeat tests or devise new ones
• Analyze and report test results

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Sequence of Steps in Scientific Experiment
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Scientific Theory

• A testable hypothesis about the cause or causes
  of a broad range of related phenomena.
• Remains open to tests, revision, and tentative
  acceptance or rejection
• Darwins view of natural selection is a respected
  scientific theory