Welcome to Biological Principles

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• Welcome to Biological Principles

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Chapter 1

• What is biology about?

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1. What is biology and life ?
2. How is life organized ?
3. How are biological systems related ?
4. How is so much diverse life classified ?
5. How did all these diverse life forms evolve ?
6. How do biologist study life ?

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Question 1 What is Biology?

• What is Biology?
• Biology is the scientific study of life
• What do we mean by life ?
• How is life defined?

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• We recognize life by the 7 things living
  organisms do
• 1) Order life is structured
• 2) Evolve organisms evolve due to their
  environments
• 3) Respond to the environment organisms change
  as their surroundings change

Fig 1.2
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• 4) Regulate organisms must maintain consistent
  internal balance regardless of external factors
• 5) Process energy organisms must harvest energy
  to do work
• 6) Grow and develop organisms get larger and
  mature over time
• 7) Reproduce organism produce offspring

Fig 1.2
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Question 2 How is all this life organized?

• Concept 1.1 Biologists explore life from the
  microscopic to the global scale
• The study of life
• Extends from the microscope scale of molecules
  and cells to the global scale of the entire
  living planet
• This is called the hierarchy of life

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A Hierarchy of Biological Organization

• The hierarchy of life
• The biosphere all the environments on Earth
  that are inhabitable by life
• Ecosystems all the living things in a
  particular area the non-living things that
  interact with life
• Communities all the living things in an
  ecosystem
• Population all the individuals of a species
  within a community

Fig 1.3
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A Hierarchy of Biological Organization

• 5) Organisms individual members of a population
• 6) Organ systems and organs team of organs that
  function together (organs are body parts made up
  of more than one type of tissue)
• 7) Tissue a group of similar cells
• 8) Cell fundamental unit of life lowest level
  of hierarchy that retains all the characteristic
  of life

Fig 1.3
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A Hierarchy of Biological Organization

• 9) Organelle functional component that make up
  a cell
• 10) Molecules chemical structure consisting of
  two or more atoms

Fig 1.3
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A Closer Look at Cells

• The cell
• Is the lowest level of organization that can
  perform all activities required for life

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Two Main Forms of Cells

• All cells share certain characteristics
• They are all enclosed by a membrane
• They all use DNA as genetic information
• There are two main forms of cells
• Eukaryotic
• Prokaryotic

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• Prokaryotic cells
• Small
• Simple
• Older (evolutionarilary speaking)
• No membrane-bound organelles
• No true nucleus
• Ex Bacteria

Figure 1.8
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• Eukaryotic cells
• Large
• Complex
• Newer (evolutionarilary speaking)
• Membrane-bound organelles
• True nucleus
• Ex White blood cell

Figure 1.8
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• Actual size comparison

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Question 3 How are biological systems related?

• The Emergent Properties of Systems
• New properties emerge with each step upward in
  the hierarchy of biological order
• Reductionism
• Involves reducing complex systems to simpler
  components that are more manageable to study

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• Feedback Regulation in Biological Systems
• A kind of supply-and-demand economy of biological
  systems
• In feedback regulation - the output, or product,
  of a process regulates that very process

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• In negative feedback
• An accumulation of an end product slows the
  process that produces that product

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• In positive feedback
• The end product speeds up production

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Question 4 How is so much diverse life
classified?

• With all the diverse life forms, how can
  biologists classify them all?

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Grouping Species The Basic Idea

• Taxonomy
• Is the branch of biology that names and
  classifies species according to a system of
  broader and broader groups

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• Classifying life

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The Three Domains of Life

• At the highest level, life is classified into
  three domains
• Bacteria
• Ex E.coli, staph, strep
• Archaea
• Ex Pyrococcus furiosus
• Eukarya
• Ex Us!

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• Domain Bacteria
• Consists of prokaryotes
• All the bacteria you can think of
• Domain Archaea
• Consist of prokaryotes
• Live in extreme environments (high heat or salt
  concentration)
• Junk drawer of classification

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• Domain Eukarya,
• Consist of eukaryotes
• Divided into several kingdoms
• Protist (multiple kingdoms, usually unicelular)
• Plantae plants
• Animalia animals
• Fungi decomposers (mushrooms)

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Unity in the Diversity of Life

• As diverse as life is
• There is also evidence of remarkable unity at the
  cellular and molecular level

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• Just as the earth has changed over billions of
  years,
• species of living organisms have evolved too

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Question 5 How did diverse life forms evolve?

• The evolutionary view of life
• Came into sharp focus in 1859 when Charles Darwin
  published On the Origin of Species by Natural
  Selection
• His two main points were
• 1) Contemporary species arose from a succession
  of ancestors
• 2) The evolutionary mechanism of natural
  selection accounts for descent with modification

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• The study of fossils
• Helped to lay the groundwork for Darwins ideas
• Fossils are remains or traces of organisms from
  the past
• Usually found in sedimentary rock, which appears
  in layers or strata

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• Paleontology, the study of fossils
• Was largely developed by French scientist Georges
  Cuvier
• Cuvier opposed the idea of gradual evolutionary
  change
• And instead advocated catastrophism, speculating
  that each boundary between strata represents a
  catastrophe

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Theories of Gradualism

• Gradualism
• Is the idea that profound change can take place
  through the cumulative effect of slow but
  continuous processes

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Lamarcks Theory of Evolution

• Jean-Baptiste de Lamarck (1744 1829)
  hypothesized that species evolve
• Through use and disuse and the inheritance of
  acquired traits
• But the mechanisms he proposed are unsupported by
  evidence

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• In 1844, Darwin wrote a long essay on the origin
  of species and natural selection
• But he was reluctant to introduce his theory
  publicly, anticipating the uproar it would cause
• In June 1858 Darwin received a manuscript from
  Alfred Russell Wallace
• Who had developed a theory of natural selection
  similar to Darwins
• Darwin quickly finished The Origin of Species
• And published it the next year

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• Darwins ideas werent new, just connected for
  the first time.
• He saw
• Individuals vary in many traits
• Individuals can produce more offspring than can
  survive, so they compete for resources

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• From these observations Darwin inferred
• Not all individuals are equally likely to survive
  and reproduce
• This unequal reproductive success can adapt a
  population to its environment

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• The products of natural selection
• Often times seem to be perfect adaptations of
  organisms to the special circumstances of their
  way of life and their environment

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• The Origin of Species articulated two main points
• Descent with modification
• Natural selection

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• Natural selection is the evolutionary process
  that occurs
• When a populations heritable variations are
  exposed to environmental factors that favor the
  reproductive success of some individuals over
  others

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Question 6 How do biologists study life?

• Biology blends two main processes of scientific
  inquiry
• Discovery science describes nature
• Hypothesis-based science explains nature

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Discovery Science

• Discovery science
• Describes natural structures and processes as
  accurately as possible through careful
  observation and analysis of data

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Induction in Discovery Science

• In inductive reasoning
• Scientists derive generalizations based on a
  large number of specific observations
• Example Ive noticed that every time I throw a
  ball up, it comes back down, so I guess that the
  next time I throw a ball up, itll come back down
  too.
• Start with many observations, see a pattern,
  create a tentative hypothesis that may lead to a
  theory

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Hypothesis-Based Science

• In science, inquiry that asks specific questions
• Tries to explain generalizations and seeks the
  causes of events observed
• Possible explanations are put on trial to see if
  they are falsifiable or not
• In science, a hypothesis
• Is a tentative answer to a well-framed question,
  an explanation on trial
• Makes predictions that can be tested

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Hypothesis-Based Science

• Uses Deductive Reasoning
• In deductive reasoning
• Uses If . . . Then logic that starts with a
  general observation and flows to a specific
  result
• Example If Newtons Law of Gravity is true, and
  I throw a ball up, then it must come down
• Start with a theory that we then narrow to a
  hypothesis that is testable, narrow it further
  through observations that may or may not confirm
  the original hypothesis

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A Closer Look at Hypotheses in Scientific Inquiry

• A scientific hypothesis must have two important
  qualities
• It must be testable have to be able to check if
  the idea is valid
• Example I can toss the ball up in the air
• It must be falsifiable there must be some
  observation that could reveal if the idea was not
  true
• Example If I observe the ball did not fall back
  down

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A Closer Look at Hypotheses in Scientific Inquiry

• Hypothesis (continued)
• Isnt ever proven true, it just hasnt been
  falsified yet
• Tested in controlled experiments where two groups
  are compared
• Experimental group
• Control group
• Only differ in 1 factor, the factor that is being
  tested

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Theories in Science

• A theory in science is different than in
  everyday usage of that word
• A scientific theory
• Is broad in scope
• Generates new hypotheses
• Is supported by a large body of evidence
• Yet it isnt proven true, just the best answer
  that fits the available data at the present