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The Science of Biology
Chapter 1
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What is Life?
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Five Basic Characteristics of living things
 Organization
- Atoms, molecules
- Cells
- Tissues, organs
- Populations, community
- Ecosystem, biosphere
Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies
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What is Life?
Five Basic Characteristics (continued)
 Energy
- Photosynthesis, respiration
 Sense and Respond
- Homeostasis
 DNA
- Growth
- Development
- Reproduction
Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies
The Nature of Science
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Deductive Reasoning
 General principles used to predict specific
results.
Inductive Reasoning
 Arriving at a conclusion based on
observations.
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How Science is Done
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Observation
Question (s)
Hypothesis
 Possible answer to the question, testable
Experiment - Test of hypothesis.
 Try to eliminate one or more competing
hypotheses.
 Establish controls by holding all variables
but one constant.
Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies
How Science is Done
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Record Results
 Data and observations
Conclusions
 Accept or reject hypotheses
Report
Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies
Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies
Hypothesis vs. Theory
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Hypothesis
 Possible answer
 Untested or limited testing done
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Theory
 Hypothesis that has been tested
 A lot of evidence to support
 Widely accepted
Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies
Darwin’s Theory of Evolution
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In Darwin’s time, most people believed
species were immutable over time (no
change since beginning)
Darwin argued species change due to the
operation of natural laws that produced
change over time (evolution).
 Served as naturalist on exploratory
expedition around coast of South America.
Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies
H.M.S. Beagle Voyage
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Inventing the Theory of Natural Selection
Darwin studied the work of other scientists:
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Charles Lyell’s Principles of Geology talked
about the age of the earth being billions of
years
 Most people believed earth to be only
thousands of years old
Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies
Inventing the Theory of Natural Selection
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Thomas Malthus’s Essay on the Principle of
Population (1798)
 Populations grow geometrically but
resources grow arithmetically.
- Even though every organism has the
potential to produce more offspring than
can survive, population sizes remain
relatively constant over time.
Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies
Darwin’s Evidence
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Darwin observed characteristics of similar
species varied from place to place.
 Geographical patterns suggested lineages
gradually change as species migrate.
 Struck that animals and plants on relatively
young islands closely resembled those on
nearby South American coast.
Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies
Inventing the Theory of Natural Selection
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Darwin made the association that individuals
that possess certain characteristics are more
likely to survive than those that do not
possess those characteristics.
 Favorable characteristics are passed on to
offspring.
- Over time, frequency of the favorable
characteristics increases in the
population.
Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies
Inventing the Theory of Natural Selection
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Darwin knew animal breeders selected certain
varieties to produce certain characteristics
(artificial selection).
 Noted character differences appeared to be
greater than those in wild populations.
- Suggested evolutionary changes could
occur in natural populations as well.
 Natural Selection
Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies
Inventing the Theory of Natural Selection
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Darwin’s Timeline
 Original draft of The Origin of Species
finished in 1842.
- Shelved for 16 years.
 Alfred Wallace sent manuscript with similar
ideas to Darwin in 1858.
 The Origin of Species released in November
1859.
Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies
Evolution After Darwin: More Evidence
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Fossil Record
 Fossils dating back 3.5 billion years add
multiple lines of evidence.
Age of the Earth
 Earth formed 4.5 bya.
Mechanisms of Heredity
 Field of genetics accounts for new
variations.
Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies
Evolution After Darwin: More Evidence
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Comparative Anatomy
 Homologous Structures - Have same
evolutionary origin, but now differ in
structure and function.
 Analogous Structures - Have similar
structure and function, but different
evolutionary origins.
Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies
Evolution After Darwin: More Evidence
Molecular Biology
- Biochemical tools
 DNA analysis
 Development Patterns
- Similarities have been noted in the
development stages of many different
organisms.

Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies
Review
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Properties of Life
The Nature of Science
 Scientific Method
Darwin’s Theory of Evolution
 Evidence
 Theory of Natural Selection
Evolution After Darwin
Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies
Copyright © McGraw-Hill Companies Permission required for reproduction or display
Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies