Invitation to Biology

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Invitation to Biology

• Chapter 1

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Biology

• Scientific study of life
• Lays the foundation for asking basic questions
  about life and the natural world

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What Am I Doing Here?

• 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

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Impacts, Issues What Am I Doing Here?

• Biology is a way of thinking critically about
  life
• Biology can help us to better understand human
  impact on nature, such as an oil field burning
  out of control during the Persian Gulf War

Fig. 1.1, p.2
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Lifes Underlying Unity

• Lifes organization extends from the molecular
  level to the biosphere
• Shared features at the molecular level are the
  basis of lifes unity

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Levels of Organization
Lifes levels of organization
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Molecules of Life

• Atoms are the basic units of matter
• Living things are made up of a certain subset of
  molecules
• Nucleic acids
• Proteins
• Carbohydrates
• Lipids

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Nothing Lives without Energy

• Energy capacity to do work
• Metabolism processes by which cells acquire
  and use energy for maintenance, growth, and
  reproduction

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Energy Flow

• Usually starts with energy from the sun
• Transfers from one organism to another
• Flows in one direction
• Eventually is lost as heat

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Interdependencies among Organisms

• Producers Make their own food
• Consumers
• Obtain energy by eating other organisms
• Decomposers Break down remains and wastes

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Energy input, from sun
Producers plants, and other self-feeding organisms
NutrientCycling
Consumers animals, most fungi, many protists,
many bacteria
Energy output (mainly metabolic heat)
Fig. 1-3, p.5
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Unity of Life

• All organisms
• Consist of one or more cells
• Have the capacity to reproduce based on
  instructions in DNA
• Engage in metabolism
• Sense and respond to the environment

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Homeostasis

• Organisms maintain certain conditions in their
  internal environment
• A defining feature of life

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Lifes Diversity

• Millions of living species
• Millions more now extinct
• Each species has someunique traits

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Classification Systems

• Organisms are grouped into three domains

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Lifes diversity
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Prokaryotes
Eukaryotes

• Single celled
• No nucleus
• Smaller, less complex
• Archaebacteria, eubacteria

• Single- or multicelled
• Nucleus
• Larger, more complex
• Fungi, protistans, plants, animals

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Bacteria

• The most common prokaryotes

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Archaea

• Prokaryotes

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Mutation Source of Variation

• Mutation change in structure of DNA
• Basis for variation in heritable traits
• May be harmful, neutral, or beneficial

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Evolution

• Heritable change in a line of descent over time
• Changes in populations result in diversity

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Scientific Method

• Observe phenomenon
• Develop hypotheses
• Make predictions
• Devise test of predictions
• Carry out test and analyze results

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Role of Experiments

• Study a phenomenon under known conditions
• Tests the prediction of the hypothesis
• 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
• Experimental group
• Includes one variable being studied

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Scientific Theory

• An explanation of the causes of a wide range of
  related phenomena
• Is consistent with all collected data
• Used to make predictions
• Still can be disproved

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Experiments with Synthetic Fat

• Question Does Olestra, a synthetic fat
  replacement made from sugar and oil, cause
  intestinal cramps?

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Designing an Experiment Olestra
p.10
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Designing an Experiment Olestra
Stepped Art
Fig. 1-8, p.10
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Limits of Science

• Scientific method
• cannot provide answers to subjective questions
• cannot provide moral, aesthetic, or philosophical
  standards
• may conflict with supernatural beliefs

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Limits of Science

• The external world, not internal conviction, is
  the testing ground for scientific theories

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Table 1-1, p.13