evolution, the themes of biology, and scientific inquiry
TRANSCRIPT
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© 2014 Pearson Education, Inc.
Chapter 1
Evolution,
the Themes of Biology,
and Scientific Inquiry
Dr. Wendy Sera
Houston Community College
Biology 1406
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Inquiring About Life
An organism’s adaptations to its environment are
the result of evolution
For example, the seeds of the dandelion are moved by
wind due to their parachute-like structures
Evolution is the process of change that has
transformed life on Earth
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Biology is the scientific study of life
Biologists ask questions such as
How does a single cell develop into an organism?
How does the human mind work?
How do living things interact in communities?
Life defies a simple, one-sentence definition
Instead, life is recognized by what living things do
Inquiring About Life, cont.
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Figure 1.2—Some Properties
of Life
Order
Energy processing
Growth and
development
Regulation
Reproduction
Response
to the
environment
Evolutionary
adaptation
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Video: Seahorse Camouflage
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Concept 1.1: The Study of Life Reveals Common Themes
Biology consists of more than memorizing factual
details
Themes help to organize biological information
Five Themes:
Organization
Information
Energy and Matter
Interactions
Evolution
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Theme: New Properties Emerge at Successive Levels of Biological Organization
Life can be studied at different levels, from
molecules to the entire living planet
This enormous range can be divided into different
levels of biological organization
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Figure 1.3—Exploring levels of biological organization
1 The Biosphere 7 Tissues
8
Cells5
Organisms
10
Mole-
cules
3
Communities
2
Ecosystems
6 Organs
and Organ
Systems
4 Populations
9 Organelles
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Levels in which life is organized: From atoms to biosphere
Atoms: the smallest unit of matter; smallest particle of an
element
Molecules: consists of 2 or more atoms (e.g., DNA, H2O)
Organelle: structure in a cell with specific function (e.g.,
chloroplast, nucleus)
Cell: Smallest unit of life (e.g., Amoeba & bacteria are
single cells)
Tissue: group of cells with a specific function
Organs & Organ systems: consists of 2 or more tissues
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Levels of Organization, continued
Organisms: Individual living things
Populations: Group of interbreeding individuals of a
species.
Communities: All organisms in an area
Ecosystems: Living things in an area along with its non-
living components
Biosphere: Part of the earth inhabited by organisms,
includes both living & non-living.
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Emergent Properties
Emergent properties result from the arrangement
and interaction of parts within a system
Emergent properties characterize non-biological
entities as well
For example, a functioning bicycle emerges only
when all of the necessary parts connect in the
correct way
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The Power and Limitations of Reductionism
Reductionism is the reduction of complex systems to
simpler components that are more manageable to
study
For example, the molecular structure of DNA
An understanding of biology balances reductionism
with the study of emergent properties
For example, new understanding comes from studying
the interactions of DNA with other molecules
Systems biology is the analysis of the interactions
among the parts of a biological system
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Structure and Function
At each level of the biological hierarchy, we find a
correlation between structure and function
Form fits function!
For example, a hummingbird’s anatomy allows the
wings to rotate at the shoulder, so unlike other
birds, they can fly backward and hover in place.
How else might the
hummingbird’s
anatomy illustrate
that form fits
function?
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The Cell is an organism’s basic unit of structure and function
The cell is the lowest level of organization that can
perform all activities required for life
All cells:
Are enclosed by a membrane
Use DNA as their genetic information
The ability of cells to divide is the basis of all
reproduction, growth, and repair of multicellular
organisms
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Cell Theory
Invention of the light microscope led to the discovery of the cell and
formulation of Cell Theory.
Robert Hooke (1665)—examined cork and coined the term “cell”
Antonie van Leeuwenhok (1600’s)—examined organisms in pond
water, blood cells, and sperm cells
Matthias Schleiden and Theodor Schwann (1839)—formulated the
first two tenets of Cell Theory
1. Cells are the basic unit of life.
2. All living things are made of cells.
Cell Theory was subsequently articulated by Rudolf Virchow in 1858
to also include:
3. All cells come from preexisting cells (a rejection of the idea of
spontaneous generation).
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A eukaryotic cell has membrane-enclosed
organelles, the largest of which is usually the
nucleus
By comparison, a prokaryotic cell is simpler and
usually smaller, and does not contain a nucleus or
other membrane-enclosed organelles
Bacteria and Archaea are prokaryotic; plants,
animals, fungi, and all other forms of life are
eukaryotic
Two Major Types of Cells
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Figure 1.4—Contrasting eukaryotic and prokaryotic
cells in size and complexity
Eukaryotic cell
Membrane
Cytoplasm
Membrane-
enclosed organelles
Nucleus
(membrane-
enclosed)
DNA (throughout
nucleus) 1 µm
Prokaryotic cell
Membrane
DNA
(no nucleus)
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Theme: Life’s Processes Involve the Expression and Transmission of Genetic Information
Within cells, structures called chromosomes
contain genetic material in the form of DNA
(deoxyribonucleic acid)
25 µm
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DNA, the Genetic Material
Each chromosome has one long DNA molecule
with hundreds or thousands of genes
Genes encode information for building the
molecules synthesized within the cell
Genes are the units of inheritance
DNA controls the development and maintenance
of organisms
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Figure 1.6—Inherited DNA
directs development of an
organismSperm cell
Egg cell
Fertilized egg
with DNA from
both parents Embryo’s cells
with copies of
inherited DNA
Offspring with
traits inherited
from both parents
Nuclei containing DNA
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Each DNA molecule is made up of two long chains
arranged in a double helix
Each chain is made up of four kinds of chemical
building blocks called nucleotides and nicknamed
A, G, C, and T
DNA, the Genetic Material, cont.
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Figure 1.7—DNA: The genetic material
Nucleus
DNA
(a) DNA double helix (b) Single strand of DNA
A
T
G
G
T
A
T
A
C
A
C
T
A
C
Nucleotide
Cell
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Genes control protein production indirectly
DNA is transcribed into RNA, which is then
translated into a protein
This is what is called Gene expression, the
process of converting information from gene to
cellular product (i.e., a protein).
Gene Expression: Making a Protein
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Figure 1.8—Gene
expression: The transfer of
information from a gene
results in a functional protein
Lens
cell
(a) Lens cells are
tightly packed
with transparent
proteins called
crystallin.
(b) How do lens cells make crystallin proteins?
Crystallin gene
DNA
mRNA
Chain of amino
acids
Protein
Crystallin protein
TRANSCRIPTION
TRANSLATION
A C C A A A C C G A G T
T G G T T T G G C T C A
U G G U U U G G C U C A
PROTEIN FOLDING
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Genomics: Large-Scale Analysis of DNA Sequences
An organism’s genome is its entire set of genetic
instructions
The human genome and those of many other
organisms have been sequenced
Genomics is the study of sets of genes within and
between species
Proteomics is the study of whole sets of proteins
encoded by the genome
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The genomics approach depends on:
“High-throughput” technology, which yields
enormous amounts of data
Bioinformatics, which is the use of computational
tools to process a large volume of data
Interdisciplinary research teams
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Theme: Life Requires the Transfer and Transformation of Energy and Matter
The input of energy from the sun and the
transformation of energy from one form to another
make life possible
When organisms use energy to perform work, some
energy is lost to the surroundings as heat
As a result, energy flows through an ecosystem,
usually entering as light and exiting as heat
On the other hand, chemicals (i.e., matter) cycle
between organisms and the physical environment.
In other words, they are recycled.
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ENERGY FLOW
Light
energy HeatChemical
energy
Plants take
up chemicals
from the soil
and air.
Chemicals
Decomposers
return
chemicals
to the soil.
Chemicals
pass to
organisms
that eat the
plants.
Figure 1.9—Energy flow and chemical cycling
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Theme: From Ecosystems to Molecules, Interactions Are Important in Biological Systems
Interactions between the components of the
system ensure smooth integration of all the parts
This holds true equally well for components of an
ecosystem and the molecules in a cell
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Ecosystems: An Organism’s Interactions with Other Organisms and the Physical Environment
At the ecosystem level, each organism interacts
continuously with other organisms
These interactions may be beneficial or harmful to
one or both of the organisms
Organisms also interact continuously with the
physical factors in their environment, and the
environment is affected by the organisms living
there
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Figure 1.10—Interactions of an African acacia tree with other organisms and the physical
environment Sunlight
Leaves take in
carbon dioxide
from the air and
release oxygen.
Animals eat leaves
and fruit from the tree,
returning nutrients
and minerals to the
soil in their waste
products.
Water and
minerals in
the soil are
taken up
by the tree
through its
roots.
Leaves absorb light
energy from the sun.
Leaves fall to the
ground and are
decomposed by
organisms that
return minerals
to the soil.
CO2
O2
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Molecules: Interactions Within Organisms
Interactions between components—organs,
tissues, cells, and molecules—that make up living
organisms are crucial to their smooth operation
Cells are able to coordinate various chemical
pathways through a mechanism called feedback
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In feedback regulation the output, or product of a
process, regulates that very process
The most common form of regulation in living
organisms is negative feedback, in which the
response reduces the initial stimulus
Negative feedback means that as more of a
product accumulates, the process that creates it
slows and less of the product is produced
Positive feedback means that as more of a
product accumulates, the process that creates it
speeds up and more of the product is produced
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Figure 1.11—Feedback regulation
Insulin
Circulation
throughout
body via
blood
Insulin-producing
cell in pancreas
STIMULUS: High
blood glucose level
Neg
ati
ve f
ee
db
ac
k
Liver and
muscle cells
RESPONSE: Glucose
uptake by liver and
muscle cells
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Animation: Negative Feedback
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Evolution, the Core Theme of Biology
Evolution is the one idea that makes logical sense
of everything we know about living organisms
The scientific explanation for both the unity and
diversity of organisms is the concept that living
organisms are modified descendants of common
ancestors
Many kinds of evidence support the occurrence of
evolution
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Concept 1.2: The Core Theme: Evolution accounts for the unity and diversity of life
“Nothing in biology makes sense except in the
light of evolution”—Theodosius Dobzhansky
Evolutionary mechanisms account for the unity
and diversity of all species on Earth
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Classifying the Diversity of Life
Approximately 1.8 million species have been
identified and named to date, and thousands more
are identified each year
Estimates of the total number of species that
actually exist range from 10 million to over 100
million
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Grouping Species: The Basic Idea
Taxonomy is the branch of biology that names
and classifies species into groups of increasing
breadth
Domains, followed by kingdoms, are the
broadest units of classification
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Figure 1.12—Classifying life
SPECIES GENUS FAMILY ORDER CLASS PHYLUM KINGDOM DOMAIN
Ursus
Ursidae
Carnivora
Mammalia
Chordata
Animalia
Eukarya
Ursus americanus
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The Three Domains of Life
Organisms are divided into three domains, named
Bacteria, Archaea, and Eukarya
Domain Bacteria and domain Archaea compose
the prokaryotes
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(a) Domain Bacteria
(c) Domain Eukarya
2 µ
m
(b) Domain Archaea
2 µ
m
100 µm
Kingdom
Animalia
Kingdom
Plantae
Kingdom
Fungi Protists
Figure 1.13—The three domains of life
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Domain Eukarya includes all eukaryotic organisms
Domain Eukarya includes three multicellular
kingdoms:
Plants, which produce their own food by photosynthesis
Fungi, which absorb nutrients
Animals, which ingest their food
Other eukaryotic organisms were formerly grouped
into the Protist kingdom, though the recent trend has
been to split the protists into several kingdoms
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Unity in the Diversity of Life
A striking unity underlies the diversity of life; for
example
DNA is the universal genetic language common to
all organisms
Unity is evident in many features of cell structure
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Figure 1.14—An example of unity underlying the diversity of life: the architecture
of cilia in eukaryotes
Cilia of
windpipe cells
Cross section
of a cilium
Cilia of
Paramecium
0.1 µm
15 µm
5 µm
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Charles Darwin and the Theory of Natural Selection
Fossils and other evidence document the
evolution of life on Earth over billions of years
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Charles Darwin and the Theory of Natural Selection
Charles Darwin published On the Origin of
Species by Means of Natural Selection in
1859
Darwin made two main points:
1. Species showed evidence of “descent
with modification” from common
ancestors
2. Natural selection is the mechanism
behind “descent with modification”
Darwin’s theory explained the duality of
unity and diversity
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Figure 1.17—Unity and diversity among birds
European robin
Gentoo penguinAmerican flamingo
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Unity and diversity in the
orchid family
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Video: Galápagos Islands Overview
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Video: Albatross Courtship Ritual
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Video: Blue-footed Boobies Courtship Ritual
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Video: Galápagos Marine Iguana
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Video: Galápagos Sea Lion
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Video: Galápagos Tortoise
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Darwin observed that
1. Individuals in a population vary in their traits,
many of which are heritable (passed from parents
to offspring)
2. More offspring are produced than survive, and
competition is inevitable
3. Species generally suit their environment
Charles Darwin’s Observations
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Darwin inferred that
1. Individuals that are best suited to their environment are
more likely to survive and reproduce (called differential
reproduction and survival)
2. Over time, more individuals in a population will have
the advantageous traits
Evolution occurs as the unequal reproductive
success of individuals
In other words, the environment “selects” for the
propagation of beneficial traits
Darwin called this process natural selection
Darwin’s Theory of Natural Selection
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Figure 1.18—Natural selection
Population
with varied
inherited
traits
Elimination
of individuals
with certain
traits
1 2 Reproduction
of survivors3 Increasing
frequency
of traits that
enhance
survival
4
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Natural selection results in the adaptation of
organisms to their environment
For example, bat wings are an example of
adaptation
Adaptation: The Result of Natural Selection
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Figure 1.UN10
Population of organisms
Hereditary
variationsOverproduction of off-
spring and competition
Environmental
factors
Differences in reproductive success
of individuals
Evolution of adaptations in the population
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The Tree of Life
“Unity in diversity” arises from “descent with modification”
For example, the forelimb of the bat, human, and horse and
the whale flipper all share a common skeletal architecture
Darwin proposed that natural selection could cause an
ancestral species to give rise to two or more descendent
species (i.e., speciation)
For example, the finch species of the Galápagos Islands are
descended from a common ancestor
Evolutionary relationships are often illustrated with treelike
diagrams called “evolutionary trees” that show ancestors
and their descendants
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Figure 1.20—Descent
with modification:
adaptive radiation of
finches on the
Galápagos Islands
Green warbler finch
COMMON
ANCESTOR
Certhidea olivacea
Gray warbler finchCerthidea fusca
Sharp-beaked ground finchGeospiza difficilis
Vegetarian finch
Platyspiza crassirostris
Mangrove finchCactospiza heliobates
Woodpecker finchCactospiza pallida
Medium tree finch
Camarhynchus pauper
Large tree finchCamarhynchus psittacula
Small tree finchCamarhynchus parvulus
Large cactus ground finchGeospiza conirostris
Cactus ground finch
Geospiza scandens
Small ground finch
Geospiza fuliginosa
Medium ground finchGeospiza fortis
Large ground finchGeospiza
magnirostris
Ca
ctu
s-flo
we
r-
ea
tersS
ee
d-e
ate
rs
Gro
un
d fin
ch
es
Tre
e fin
ch
es
Inse
ct-e
ate
rs
Bu
d-
ea
ter
Se
ed
-
ea
ter
Inse
ct-e
ate
rs
Wa
rble
r
finc
he
s
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Concept 1.3: In studying nature, scientists make observations and then form and test hypotheses
The word Science is derived from Latin and means
“to know”
Science is ONE “way of knowing”
What are some other “ways of knowing?”
Inquiry is the search for information and
explanation of natural phenomena
There are two main types of scientific inquiry:
discovery science and hypothesis-based
science
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Making Observations: Discovery Science
Biologists describe natural structures and
processes using Discovery Science
This approach is based on observation and the
analysis of data
Recorded observations are called data
Qualitative data often take the form of recorded
descriptions
Quantitative data are generally expressed as
numerical measurement, organized into tables and
graphs
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Figure 1.21—Jane Goodall collecting qualitative data on chimpanzee behavior
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Induction in Discovery Science
Inductive reasoning draws conclusions through
the logical process of induction
Induction is making an inference from a set of
specific observations to reach a general
conclusion called a generalization.
For example, “the sun always rises in the east”
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Forming and Testing Hypotheses: Hypothesis-Based Science
Observations can lead us to ask questions and
propose hypothetical explanations called
hypotheses
A hypothesis is a tentative answer to a well-
framed question
It is usually a rational accounting for a set of
observations
A scientific hypothesis leads to predictions that
can be tested by observation or experimentation
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For example
Observation: Your flashlight doesn’t work
Question: Why doesn’t your flashlight work?
Hypothesis 1: The batteries are dead
Hypothesis 2: The bulb is burnt out
Both these hypotheses are testable
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Figure 1.22—A
simplified view
of the scientific
process
Observation: Flashlight doesn’t work.
Question: Why doesn’t the flashlight work?
Hypothesis #1:
Batteries are dead.
Hypothesis #2:
Bulb is burnt out.
Prediction: Replacing
bulb will fix problem.
Test of prediction:
Replace bulb.
Result:
Flashlight works.
Hypothesis is supported.
Result:
Flashlight doesn’t work.
Hypothesis is contradicted.
Test of prediction:
Replace batteries.
Prediction: Replacing
batteries will fix problem.
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Deduction Reasoning: The “If…then” Logic of Hypothesis-Based Science
Deductive reasoning uses general premises to
make specific predictions
Usually takes the form of “If…then” logic
For example, if organisms are made of cells
(premise 1), and humans are organisms (premise
2), then humans are composed of cells (a
deductive prediction)
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A Closer Look at Hypotheses in Scientific Inquiry
A hypothesis must be testable and falsifiable
Hypothesis-based science often makes use of two or
more alternative hypotheses
Failure to falsify a hypothesis does not prove that
hypothesis
For example, you replace your flashlight bulb, and it now
works; this supports the hypothesis that your bulb was burnt
out, but does not prove it (perhaps the first bulb was inserted
incorrectly)!
We can never prove that a hypothesis is true, but
testing it in many ways with different sorts of data can
increase our confidence in it tremendously
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Limitations of Science
In science, observations and experimental results must be
repeatable and testable
Science cannot support or falsify supernatural or religious
explanations, which are simply outside the bounds of science.
This limits the scope of questions that science can answer.
Consider the following:
Hypothesis: God exists
Prediction: IF God exists, THEN he or she is all-powerful and could
strike me dead if I asked.
Test of Prediction: God will strike me dead if I ask.
Problem: not a testable prediction because it does not prove or
disprove the existence of a God! The hypothesis is outside the
realm of science, although nonetheless a legitimate question!
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The Flexibility of the Scientific Method
The scientific method is an idealized process of
inquiry
Hypothesis-based science is based on the
“textbook” scientific method, but rarely follows all
the ordered steps
Discovery science has made important
contributions with very little dependence on the
scientific method!
Backtracking and “rethinking” may be necessary
part way through the process
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A Case Study in Scientific Inquiry: Investigating Coat Coloration in Mouse Populations
Color patterns of animals vary widely in nature,
sometimes even between members of the same
species
Two populations of mice belonging to the same
species (Peromyscus polionotus) but with different
color patterns are found in different environments
The beach mouse lives on white sand dunes with
sparse vegetation; the inland mouse lives on
darker soil
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Figure 1.24—Different coloration in beach and inland populations of
Peromyscus polionotus
Florida
Inland population
Beach
population
Beach population
GULF OF
MEXICO
Inland population
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The two types of mice match the coloration of their
habitats
Natural predators of these mice are all visual
hunters
Francis Bertody Sumner hypothesized that the
color patterns had evolved as adaptations to
protect the mice from predators
Hopi Hoekstra and a group of students then tested
this hypothesis
A Case Study in Scientific Inquiry: Investigating Coat Coloration in Mouse Populations, cont.
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The researchers predicted that mice that did not
match their habitat would be preyed on more
heavily than mice that did match the surroundings
They built models of mice, painted them to match
one of the surroundings, and placed equal
numbers of each type of model in each habitat
They then recorded signs of predation
A Case Study in Scientific Inquiry: Investigating Coat Coloration in Mouse Populations, cont.
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Figure 1.25—Inquiry: Does camouflage affect predation rates on two
populations of mice?
Light models Dark models Light models Dark models
Camouflaged Non-camouflaged Non-camouflaged Camouflaged
(control) (experimental) (experimental) (control)
Beach habitat Inland habitat
Perc
en
tag
e o
f
att
acked
mo
dels 100
50
0
Results
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Experimental Variables and Controls
In a controlled experiment, an experimental
group (the non-camouflaged mice in this case) is
compared with a control group (the camouflaged
mice)
Ideally, experimental and control groups differ in
only the one factor under investigation
Without controls the researchers would not be
able to rule out other factors besides model color
that might have affected the results
A controlled experiment does not mean that all
unwanted variables are kept constant!
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Theories in Science
In the context of science, a theory is
Broader in scope than a hypothesis
General, and can lead to new testable hypotheses
Supported by a large body of evidence in
comparison to a hypothesis
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Concept 1.4: Science benefits from a cooperative approach and diverse viewpoints
Most scientists work in teams, which often include
graduate and undergraduate students
Good communication is important in order to share
results through seminars, publications, and
websites
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Building on the Work of Others
Scientists check each other’s claims by performing
similar experiments
If experimental results are not repeatable, the
original claim will have to be revised
It is not unusual for different scientists to work on
the same research question
Scientists cooperate by sharing data about model
organisms (for example, the fruit fly Drosophila
melanogaster)
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Science, Technology, and Society
The goal of science is to understand natural
phenomena
The goal of technology is to apply scientific
knowledge for some specific purpose
Science and technology are interdependent
Biology is marked by “discoveries,” while
technology is marked by “inventions”
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The combination of science and technology has dramatic
effects on society
For example, the discovery of DNA by James Watson
and Francis Crick allowed for advances in DNA
technology such as testing for hereditary diseases
Ethical issues can arise from new technology, but have as
much to do with politics, economics, and cultural values as
with science and technology
Figure 1.26—DNA technology and crime scene investigation
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Can you pick out the
mossy leaf-tailed gecko
lying against the tree
trunk in this photo?
How is the appearance
of the gecko a benefit in
terms of survival?
Given what you have
learned about evolution,
natural selection, and
genetic information,
describe how the
gecko’s coloration might
have evolved.