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Welcome to Biological
Principles
Copyright © 2006 Cynthia Garrard publishing under Canyon Design
Chapter 1
What is biology about?
Copyright © 2006 Cynthia Garrard publishing under Canyon Design
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 ?
Copyright © 2006 Cynthia Garrard publishing under Canyon Design
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
1) The biosphere – all the environments on
Earth that are inhabitable by life
2) Ecosystems – all the living things in a
particular area & the non-living things that
interact with life
3) Communities – all the living things in an
ecosystem
4) 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
Figure 1.5
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25 µm
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
EUKARYOTIC CELL
Membrane
PROKARYOTIC CELL
DNA
(no nucleus)
Membrane
Cytoplasm
Organelles
Figure 1.8
Nucleus (contains DNA)
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1 µm
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
A
Negative
feedback
Enzyme 1
B
A
Enzyme 1
B
Enzyme 2
C
C
Enzyme 3
D
D
D
D
Figure 1.11
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D
D
D
D
D
D
D
• In positive feedback
– The end product speeds up production
W
W
Enzyme 4
Enzyme 4
Positive
feedback
X
X
Enzyme 5
Enzyme 5
Y
Y
Enzyme 6
Z
Enzyme 6
Z
Z
Z
Z
Z
Z
Z
Figure 1.12
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Z
Z
Z
Z
Z
Z
Z
Z
Z
Z
Z
Question 4: How is so much diverse life classified?
• With all the diverse life forms, how can
biologists classify them all?
Figure 1.13
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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
Species Genus Family
Order
Class
Phylum
Ursus
americanus
(American
black bear)
Ursus
Ursidae
Carnivora
Mammalia
Chordata
Animalia
Figure 1.14
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Eukarya
Kingdom
Domain
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
Cilia of Paramecium.
15 µm
1.0 µm
The cilia of Paramecium
propel the cell through
pond water.
5 µm
Figure 1.16
Cross section of cilium, as viewed
with an electron microscope
Cilia of windpipe cells. The cells that line the human
windpipe are equipped with cilia that help keep the lungs
clean by moving a film of debris-trapping mucus upward.
Copyright © 2006 Cynthia Garrard publishing under Canyon Design
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:
Figure 1.18
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 Darwin’s ideas
• Fossils are remains or traces of organisms from
the past
– Usually found in sedimentary rock, which appears in
layers or strata
Figure 22.3
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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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Lamarck’s 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
Figure 22.4
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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 Darwin’s
• Darwin quickly finished The Origin of Species
– And published it the next year
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•
Darwin’s ideas weren’t new, just connected
for the first time.
•
He saw:
1) Individuals vary in many traits
2) Individuals can produce more offspring than
can survive, so they compete for resources
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•
From these observations Darwin inferred:
1) Not all individuals are equally likely to survive
and reproduce
2) 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
Figure 1.19
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• Natural selection is the evolutionary process that
occurs
– When a population’s heritable variations are exposed
to environmental factors that favor the reproductive
success of some individuals over others
1
Populations with varied inherited traits
2 Elimination of individuals with certain traits.
3 Reproduction of survivors.
Figure 1.21
4 Increasing frequency of traits that enhance
survival and reproductive success.
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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: I’ve 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, it’ll 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 Newton’s 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)
–
Isn’t ever “proven true”, it just hasn’t been
falsified yet
–
Tested in controlled experiments where two
groups are compared:
1) Experimental group
2) 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 isn’t “proven true”, just the best answer that
fits the available data at the present
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