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Introduction to Biology
Lecture 1
Fall 2008
What is Biology?
Biology –
The scientific study of life
• What is science?
• What is life?
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Life
What is life??
Fig. 1.3
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Themes in Biology
1. Cells are an
organism’s basic units
of structure and function
• The lowest level of
structure that can
perform all activities
required for life
Fig. 1.8
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Themes in Biology
2. Continuity of
life is based on
heritable
information in
the form of DNA
Fig. 1.10
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Themes in
Biology
3. Structure and
Function are
correlated at
all levels of
biological
organization
See Fig. 1.4
Themes in Biology
4. Emergent properties
• The whole is greater than the sum of its parts
• New properties emerge with each step upward
in the hierarchy of life
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Themes in Biology
• Reductionism & Systems Biology
Fig. 1.10
Fig. 1.12
Themes in Biology
5. Organisms interact
with their
environments,
exchanging matter
and energy
Fig. 1.5
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Themes in Biology
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6. Feedback mechanisms regulate biological
systems
•
Negative & Positive feedback
Fig. 40.8
Fig. 40.16
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Themes in Biology
6. Evolution is the
theme that unifies
all biology
“Nothing in biology
makes sense
except in the light of
evolution”
- Theodosius
Dobzhansky
See Fig. 1.22
Themes in Biology
Diversity and Unity –
the dual nature of life
• All life unified by basic
properties
• Vast diversity of
biological forms
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Globally - ~1.8 million
species
~10,000 birds
~ 4629 mammals
~ 8240 reptiles
~ 900,000 insects (named)
~ 300,000 vascular plants
~ 20,000 fish
Washington State
~ 466 birds
~ 139 mammals
~ 25 reptiles
~ 3200 plants
~ 211 fish (Puget sound)
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Themes in
Biology
• Diversity
and Unity
Fig. 1.14
See Fig. 1.15
The Theory of Evolution by Natural
Selection
Evolution:
- a genetically based change in the characteristics
of a population over time.
Explains the diversity and similarity of organisms;
how organisms have come to be adapted to a
wide range of environments.
Process = Natural selection
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The Theory of Evolution by Natural
Selection
1. Individuals within a population vary in traits.
2. At least some of the variation must be heritable
so it can be passed onto offspring (DNA).
3. In every generation, more offspring are
produced than can survive (overproduction
and competition).
4. Unequal reproductive success - Survival and
reproduction of individuals is not random.
Outcome of process: Population’s characteristics
will change over time = Evolution will occur.
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The Theory of
Evolution by Natural
Selection
Fig. 1.20
Artificial Selection
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Why study biology??
What is Science?
What is Science?
• A way of knowing, based on inquiry
• A search for an understanding of the
natural world
• Attempts to discover order in nature and to
use that knowledge to make predictions
about what should happen in nature
• Exploring and explaining the world
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What is Science?
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Science seeks natural causes for natural phenomena
Discovery Science
• Descriptive science
• Based on observations & measurements
• Inductive reasoning – generalization that
summarizes a large number of observations
• “bottom-up
What is Science?
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Science seeks natural causes for natural phenomena
Hypothesis-driven Science
• Asking questions and seeking explanations
• Scientific Method
• Deductive reasoning – moves from general to more
specific
• “top-down”
The Scientific Method
Make observations
Prompts questions
Formulate a hypothesis
Makes a testable prediction
Test hypothesis:
Experimental design and
data collection
New observations or
controlled experiments
Analyze & interpret data
Supports or refutes
hypothesis?
Draw conclusions
Publish results
Scientific hypothesis: A proposed explanation; An educated
guess that attempts to explain an observed pattern.
Prediction: A statement of what you should be able to
measure or observe in nature if the hypothesis is correct.
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The Scientific Method
• Skepticism
• Peer Review
• Reproducibility
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Scientific Theory
Common usage – Theory:
(2) Abstract reasoning, speculation.
(4) An assumption based on limited information or
knowledge, a conjecture.
The American Heritage Dictionary, 3rd Ed. 1992
Scientific Theory:
Well-tested and widely accepted
scientific hypothesis
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Scientific Uncertainty
Quantitative Data
• Precise and easily compared
• Good benchmark for measuring change
Statistics
• Important in both planning and evaluating
scientific studies
• Sample size, number of replications important
Probability
• Measure of how likely something is
• High degree of scientific certain, 95% probability
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Dry Falls & the Missoula Floods
J. Harlen Bretz
1923 - Geology of
channeled scablands
in eastern WA due to
flooding on a massive
sale
J.K.Barndt, 2004
1940 – evidence of a huge lake in
Montana that had emptied rapidly
1950 - Aerial photography – Bretz’s work
finally accepted
Regrowth of insulin producing beta cells
Scientific American, Dec 2006
2001 Dr. Denise Foustman published work on regrowth of
insulin producing beta cells to help cure diabetes
“Consensus” science believed this was not possible
2006 – 3 groups reported in Science that Dr. Foustman’s
work had been reproduced
The scientific method – a case study
Fig. 1.25
Observations:
• Two snakes look alike
• Predators rarely attack eastern coral snake
• Eastern coral snake is poisonous, scarlet king
snake is not
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The scientific method – a case study
Fig. 1.25
Question:
• Does the mimicry protect the Scarlet king
snake?
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The scientific method – a case study
Fig. 1.25
Hypothesis:
• The king snake mimicry of the coral snake helps
protect it from predators in areas where the two
species ranges overlaps
Prediction:
• Predators will attack snakes with rings of bright
red, yellow and black less frequently than plain
snakes
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The scientific method – a case study
Experiment:
• Create two types of
artificial snakes
– Colored
– Plain
• Record how many attacks
occur on each type
Results:
• Support hypothesis
Conclusion:
• Mimicry reduces the
amount of predation on
the Scarlet king snake
where the two ranges
overlap
Fig. 1.27
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