chapter 1 gen bio
DESCRIPTION
chapter 1 biology notesTRANSCRIPT
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Introduction: Themes in the Study of Life Chapter 1
1
You will be able to:
1. Briefly describe the unifying themes that
characterize the biological sciences
2. Distinguish among the three domains of
life, and the eukaryotic kingdoms
3. Distinguish between the following pairs of
terms: discovery science and hypothesis-
based science, quantitative and qualitative
data, inductive and deductive reasoning,
science and technology
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Biology:
The scientific study of life
Biologists answer such questions as:
o How does a single cell develop into an organism?
o How does the human mind work?
o How do living things interact in communities (ex forest)?
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What is Life?
Life defies a simple, one-sentence definition
Life is recognized by what living things do
Properties and processes associated with life:
o Have order
o Evolutionary adaptation
o Respond to environment
o Regulation
o Energy processing
o Growth and development
o Reproduction
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Fig. 1-3a
Order
Perfectly ordered to work
-Patterned
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Fig. 1-3b
Evolutionary adaptation
o Appearance of pigmy
sea horse camouflages it
within its environment.
o Such adaptations evolve
over many generations.
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Fig. 1-3c
Response to the environment
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Venus flytrap closes
its trap rapidly in
response to the
environmental
stimulus of a damselfly
Reproduction
As a group, maybe
not all individuals
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Fig. 1-3e
Growth and development 9
Inherited information
carried by genes
controls the pattern of
growth and
development
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Fig. 1-3f
Energy processing
o Change energy to
other forms, to
accomplish a task
o Ex hummingbird
obtains fuel in the form
of nectar from flowers
o The chemical energy
stored in the food will
power flight and other
work
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Fig. 1-3g
Regulation
o Maintain conditions
suitable for life
(temperature, blood
sugar, etc)
o Ex jackrabbits ears used to maintain
constant body
temperature
o Blood vessels in ears
adjust heat exchange
with surrounding air
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Themes Connect the Concepts of Biology
1. New properties emerge at each level in the biological hierarchy
2. Organisms interact with other organisms and the physical
environment
3. Life requires energy transfer and transformation
4. Structure and function are correlated at all levels of biological
organization
5. Cells are an organisms basic units of structure and function 6. The continuity of life is based on heritable information in the
form of DNA
7. Feedback mechanisms regulate biological systems
8. Evolution is the overarching theme of biology
o Biology consists of more than memorizing factual details
o 8 unifying themes help to organize biological information and
make sense of biological information
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Theme 1: New properties emerge at each
level in the biological hierarchy o Biological organization is based on hierarchy of structural
levels, each building on the levels below
o At the lowest level are atoms which are organized into
complex molecules
Molecules
Atoms
Chlorophyll molecule
Molecule: Chemical structure that consists of 2 or more small chemical units called atoms
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Theme 1: New properties emerge at each
level in the biological hierarchy
o Molecules are organized into organelles
Chloroplast
1 m
Organelles
Organelle: Functional components within a cell Example - Chloroplast
Cell
Cells
10 m
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o Cells, containing organelles, are
the fundamental unit of structure
and function of living things
o Some organisms have one cell
(unicellular), some have many
(multicellular)
o Whether unicellular or
multicellular, all organisms uptake
and process nutrients, excrete
waste, respond to environmental
stimuli, and reproduce.
Theme 1: New properties emerge at each
level in the biological hierarchy
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Theme 1: New properties emerge at each
level in the biological hierarchy o Multicellular organisms have 3 major structural levels above a
cell: tissues, organs, and organ systems.
Tissues
50 m
Tissue: Group of similar cells Example - Epidermis
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Theme 1: New properties emerge at each
level in the biological hierarchy o Multicellular organisms have 3 major structural levels above a
cell: tissues, organs, and organ systems.
Organs and organ systems
Organ: Body part with multiple tissue types to do a job. Leaf
Organ System: Multiple organs that work together to do a job
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Organisms
The tree with the tree house
Theme 1: New properties emerge at each
level in the biological hierarchy
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Populations
Organisms make up populations: localized groups of organisms belonging to the same species Example - Sugar Maple Trees (Acer saccharum) and white-tailed deer
Theme 1: New properties emerge at each
level in the biological hierarchy
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Communities
Populations of several species in the same area combine to form a biological community. The living things in an ecosystem Example - trees, bears, birds, mushrooms, etc
Theme 1: New properties emerge at each
level in the biological hierarchy
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Ecosystems
Populations interact with their physical environment
to form ecosystems. Particular area and everything interacting within it Example - Forrest (water, trees, bears, air, etc),
grasslands, desert, and coral reef
Theme 1: New properties emerge at each
level in the biological hierarchy
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The biosphere
Biosphere: Area of earth inhabited by living things most regions of the land, most bodies of water, and the atmosphere
Theme 1: New properties emerge at each
level in the biological hierarchy
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Ways to Arrange/Organize Biology
The biosphere
Ecosystems Tissues
Organs and organ systems
Communities
Populations
Organisms
Organelles Cells
Atoms
Molecules
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Largest
Smallest
1. Biosphere
2. Ecosystems
3. Communities
4. Populations
5. Organisms
6. Organs and Organ Systems
7. Tissues
8. Cells
9. Organelles
10.Molecules
Levels of Biological Organization
Make sure to know order
and examples of each
organization level
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Emergent Properties
o Emergent properties result from the arrangement and
interaction of parts within a system
o Characteristics of something that only appear when the
component parts are put together a certain way &
interact
o Separate from the individual parts
o Emergent properties characterize nonbiological entities
as well
o For example, a functioning bicycle emerges only
when all of the necessary parts connect in the correct
way
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Theme 1: New properties emerge at each
level in the biological hierarchy
Emergent Properties o Chain+Tires+Seat+Frame+Bolts + Put Together =
Bicycle
o No individual part can transport itself or a person
o Skin+Hair+Muscle+Bone+Blood+Nerves+Brain+Etc. + Put Together = Your Body
o No single cell can take a college class
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o Reductionism is the reduction of complex
systems to simpler components that are more
manageable to study
o For example, studying the molecular structure
of DNA helps us to understand the chemical
basis of inheritance
o An understanding of biology balances
reductionism with the study of emergent
properties
o For example, new understanding comes from
studying the interactions of DNA with other
molecules
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The Power and Limitations of
Reductionism
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Systems Biology
o A system is a combination of components that
function together (and have emergent properties)
o Systems biology constructs models for the
dynamic behavior of whole biological systems
o Able to predict how a change in one or more
variables will affect other components and the
whole system
o The systems approach poses questions such as
o How does a drug for blood pressure affect
other organs?
o How does increasing CO2 alter the biosphere?
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Theme 2: Organisms Interact with Other
Organisms and the Physical Environment
o Every organism interacts with its environment, including
nonliving factors and other organisms
o Both organisms and their environments are affected by
the interactions between them
oFor example, a tree takes up water and minerals from
the soil and carbon dioxide from the air; the tree
releases oxygen to the air and roots help form soil
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Animals eat
leaves and fruit
from the tree.
Leaves take in carbon dioxide from the air and release oxygen.
Sunlight
CO2
O2
Cycling
of
chemical
nutrients
Leaves fall to the ground and are decomposed by organisms that return minerals to the soil.
Water and minerals in the soil are taken up by the tree through its roots.
Leaves absorb light energy from the sun.
Figure 1.5
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Theme 3: Life Requires Energy
Transfer and Transformation
o A fundamental characteristic of living organisms is
their use of energy to carry out lifes activities
o Work, including moving, growing, and reproducing,
requires a source of energy
o Living organisms transform energy from one form
to another
o For example, light energy is converted to chemical
energy, then kinetic energy
o Energy flows through an ecosystem, usually
entering as light and exiting as heat
The dynamics of an ecosystem include two major processes: 1. Cycling of nutrients, in which materials acquired by plants eventually
return to the soil
2. The flow of energy from sunlight to producers to consumers
Energy flows through an ecosystem, usually entering as light and exiting as
heat
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Heat
Producers absorb light energy and transform it into chemical energy.
Chemical energy
Chemical energy in food is transferred from plants to consumers.
(b) Using energy to do work (a) Energy flow from sunlight to producers to consumers
Sunlight
An animals muscle cells convert chemical energy from food to kinetic energy, the energy of motion.
When energy is used to do work, some energy is converted to thermal energy, which is lost as heat.
A plants cells use chemical energy to do work such as growing new leaves.
Theme 4: Structure and Function are
correlated at all levels of biological
organization
Structure & function of living organisms are
closely related
Example, a leaf is thin and flat, maximizing the capture of light
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(a) Wings a birds wings are aerodynamically efficient shaped
(c) Neurons especially well structured for communication within
the body
(b) Bones wing bones have honeycombed internal structure that
is strong but lightweight
Infoldings of membrane
Mitochondrion
(d) Mitochondria inner membrane carry out many steps in energy production. Infoldings pack a large amount of this membrane into a small space
0.5 m 100 m
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o The cell is the lowest level of organization that can perform all activities required for life
o You are made of trillions of cells (You are an emergent property!)
o All cells:
o Are enclosed by a membrane
o Use DNA as their genetic information
Theme 5: Cells are an organisms basic units of structure and function
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Eukaryote vs. Prokaryote o There are 2 basic types of cells: eukaryote
and prokaryote
o A eukaryotic cell has membrane-enclosed
organelles, the largest of which is usually the
nucleus
o By comparison, a prokaryotic cell is simpler
and usually smaller, and does not contain a
nucleus or other membrane-enclosed
organelles
oContains DNA (not in nucleus), plasma
membrane, cytoplasma, and ribosomes only
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Eukaryotic cell
Prokaryotic cell
Cytoplasm
DNA (no nucleus)
Membrane
Nucleus
(membrane-
enclosed)
Membrane
Membrane-
enclosed organelles
DNA (throughout
nucleus) 1 m
Figure 1.8
o Chromosomes contain most of a cells genetic material in the form of DNA (deoxyribonucleic acid)
o DNA is inherited by offspring from their parents
o DNA controls the development and maintenance of
organisms
o The instructions to make physical characteristics
o Genes are the units of inheritance that transmit
information from parents to offspring
o Portions of total DNA
o The instructions to make one heritable characteristic
o The conceptual sentences on the physical page of DNA
Theme 6: The Continuity of Life is Based on
Heritable Information in the Form of DNA
o Each chromosome has
one long DNA molecule
with hundreds or
thousands of genes
o Each DNA molecule is
made up of two long
chains arranged in a
double helix
o Each link of a chain is
one of four kinds of
chemical building blocks
called nucleotides and
nicknamed A, G, C, and
T
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DNA Structure and Function
Nucleotide
(b) Single strand of DNA
A
C
T
T
A
A
T
C
C
G
T
A
G
T
(a) DNA double helix
A
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o Living things are made of & by chemicals called
proteins
o Genes are the instructions to make a protein
o Genes control protein production indirectly
o DNA is transcribed into RNA then translated into a
protein (THE CENTRAL DOGMA)
o Gene expression is the process of converting
information from gene to cellular product
o An organisms genome is its entire set of genetic instructions
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Theme 7: Feedback Mechanisms
Regulate Biological Systems o Feedback mechanisms allow biological processes to
self-regulate
o Negative feedback means that as more of a product
accumulates, the process that creates it slows and
less of the product is produced in life, most common
o 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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Fig. 1-13
Negative feedback
Excess D blocks a step
D
D D
A
B
C
Enzyme 1
Enzyme 2
Enzyme 3
D
(a) Negative feedback
Accumulation of product D
inhibits the 1st enzyme
in the sequence, thus
slowing down production of
more D
W
Enzyme 4
X Positive feedback
Enzyme 5
Y
+
Enzyme 6
Excess Z stimulates a
step
Z
Z
Z
Z
(b) Positive feedback
A product stimulates an enzyme,
Increasing the rate of production
of the product
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o Nothing in biology makes sense except in the light of evolutionTheodosius Dobzhansky
o Evolution makes sense of everything we know about
biology
o Evolution is defined as decent with modification
o The idea that living species are descendants of
ancestral species that were different from the present-
day ones
o Evolution unifies biology at different scales of size
throughout the history of life on Earth
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The Core Theme 8: Evolution
accounts for the unity and diversity of
life
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Organizing the Diversity of Life
o Approximately 1.8 million species have been identified and
named to date, and thousands more are identified each
year
o 100,000 fungi
o 290,000 plants
o 52,000 vertebrates
o 1,000,000 insects
o Estimates of the total number of species that actually exist
range from 10 million to over 100 million
o How do we organize the vast amount of species?
o Taxonomy is the branch of biology that
names and classifies species into groups of
increasing breadth
o Organisms are classed based on similar
characteristics
o Domains, followed by kingdoms, are the
broadest units of classification
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Grouping Species: The Basic Idea
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Fig. 1-14
Species Genus Family Order Class Phylum Kingdom Domain
Ursus americanus
(American black bear)
Ursus
Ursidae
Carnivora
Mammalia
Chordata
Animalia
Eukarya
Dashing King Philip Came
Over For Good Soup.
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Broad
Specific
1. Domain
2. Kingdon
3. Phylum
4. Class
5. Order
6. Family
7. Genus
8. Species
o Organisms are divided into three domains
o Domain Bacteria and domain Archaea comprise the prokaryotes
o Domain Eukarya includes all eukaryotic organisms
The Three Domains of Life
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Figure 1.15
(a) Domain Bacteria (b) Domain Archaea
(c) Domain Eukarya
2
m
2
m
100 m
Kingdom Plantae
Kingdom Fungi
Protists
Kingdom Animalia
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(a) Domain Bacteria
2
m
oComprised of bacteria
oMost diverse and widespread
oPROKARYOTES
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(b) Domain Archaea
2
m
oMany live in extreme environments
including salty lakes and boiling hot
springs
oPROKARYOTES
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oDomain Eukarya includes all eukaryotic
organisms
oDomain Eukarya includes three multicellular
kingdoms o Plants, which produce their own food by
photosynthesis
o Fungi, which absorb nutrients from their
surroundings and often decompose dead
organisms and organic wastes o Animals, which ingest their food
Domain Eukarya
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(c) Domain Eukarya
100 m
Kingdom Plantae
Kingdom Fungi
Protists
Kingdom Animalia
multicellular
multicellular
multicellular
unicellular
In the past: Single-celled eukaryotic organisms were formerly
grouped into a kingdom called Protista, though these are now
often grouped into many separate kingdoms
Organism Groups: Energy Use
o Producers-Receive energy from non-living thing (ex. sunlight) and convert it into form living things can use (chemical energy) (ex. Sugar)
oPlants, some Bacteria
o Consumers-Can only use (eat) chemical bonds (i.e., need food) from living things
oDependent upon Producers
oAnimals, Fungi, You 53
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Unity in the Diversity of Life
Life is diverse (Domains, Kingdoms, etc), but living things show many similar characteristics
o A striking unity underlies the diversity of life:
o All Organisms are made of One OR Many Cells
o Many features of cell structure are the same or similar
o DNA is the universal genetic language common to all organisms (the instructions to build a living thing)
o Behavior is also similar within Taxonomic Groups
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Figure 1.16
Cilia of Paramecium
15 m
Cross section of a cilium, as viewed with an electron microscope
0.1 m
Cilia of windpipe cells
5 m
Theory of Natural Selection Theory Behind Similarities
Charles Darwin published On the
Origin of Species by Means of
Natural Selection in 1859
2 main points:
1. Species showed evidence of
descent with modification from common ancestors
2. Natural selection is the mechanism
behind descent with modification 56
Darwin observed that:
o Individuals in a population have traits that vary
oMany of these traits are heritable (passed from
parents to offspring)
oMore offspring are produced than survive
oCompetition is inevitable
oSpecies generally suit their environment
o57
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Darwin inferred that:
o Individuals that are best suited to their
environment are more likely to survive and
reproduce
oOver time, more individuals in a population will
have the advantageous traits
oEventually, the population is different than it was
o The natural environment selects for beneficial traits
o Darwin called this process natural selection
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Fig. 1-20
Population with varied inherited traits.
Elimination of individuals with certain traits.
Reproduction of survivors.
Increasing frequency of traits that enhance survival and reproductive success.
4 3 2 1
Beetle population:
Mixed Colors
After Forest Fire (ground covered with black ash)
Birds see &
eat lighter beetles
Darker beetles
survive & reproduce
Future
beetles
darker than
ancestors
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The Tree of Life
o Unity in diversity arises from descent with modification
o For example, the forelimb of the bat, human, and
horse and the whale flipper all share a common
skeletal architecture
o Fossils provide additional evidence of anatomical
unity from descent with modification
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o Darwin proposed that natural selection could
cause an ancestral species to give rise to two or
more descendent species
o For example, the finch species of the Galpagos
Islands are descended from a common ancestor
o 14 species of finches diversified adapting to
exploit different food sources on different islands
o Evolutionary relationships are often illustrated with
treelike diagrams that show ancestors and their
descendants
COMMON
ANCESTOR
Green warbler finch
Certhidea olivacea
Gray warbler finch
Certhidea fusca
Sharp-beaked
ground finch
Geospiza difficilis
Vegetarian finch
Platyspiza crassirostris
Mangrove finch
Cactospiza heliobates
Woodpecker finch
Cactospiza pallida
Medium tree finch
Camarhynchus pauper
Large tree finch
Camarhynchus psittacula
Small tree finch
Camarhynchus parvulus
Large cactus
ground finch
Geospiza conirostris
Cactus ground finch
Geospiza scandens
Small ground finch
Geospiza fuliginosa
Medium ground finch
Geospiza fortis
Large ground finch
Geospiza
magnirostris
Inse
ct-e
ate
rs
Seed
-ea
ter B
ud
-ea
ter
Inse
ct-e
ate
rs
Tre
e fin
ch
es
Gro
un
d fin
ch
es
Seed
-ea
ters
Ca
ctu
s-flow
er-
ea
ters
Wa
rble
r finch
es
Figure 1.22
Concept 1.3: In studying nature,
scientists make observations and
then form and test hypotheses
o The word science is derived from Latin and
means to know
o Inquiry is the search for information and
explanation
o There are two main types of scientific inquiry:
discovery science and hypothesis-based science
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64
Discovery Science (Inductive
Reasoning)
o Discovery science describes natural structures
and processes
o This approach is based on observation and the
analysis of data
o Data are recorded observations or items of
information
65
Types of Data
o Data falls into 2 categories:
oQualitative data, or descriptions rather than
measurements
oFor example, There are many people in the
room
oQuantitative data, or recorded
measurements, which are sometimes
organized into tables and graphs
oFor example, There are 24 people in the
room
Inductive Reasoning
Scientists use inductive reasoning to derive
generalizations based on a large number of
specific observations
For example, The sun always rises in the east
o Observations and inductive reasoning can
lead us to ask questions and propose
hypothetical explanations called
hypotheses
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The Role of Hypotheses in Inquiry
o A hypothesis is a tentative answer to a well-
framed question
o A scientific hypothesis leads to predictions that
can be tested by observation or experimentation
o For example, o Observation: Your flashlight doesnt work o Question: Why doesnt your flashlight work? o Hypothesis 1: The batteries are dead
o Hypothesis 2: The bulb is burnt out
o Both these hypotheses are testable
Observations
Question
Hypothesis #1:
Dead batteries
Hypothesis #2:
Burnt-out bulb
Prediction:
Replacing batteries
will fix problem
Prediction:
Replacing bulb
will fix problem
Test prediction Test prediction
Test falsifies hypothesis Test does not falsify hypothesis
Both these
hypotheses
are testable
The
Scientific Method
68
Deductive reasoning uses general premises
to make specific predictions
For example:
If organisms are made of cells (premise 1),
And humans are organisms (premise 2),
Then humans are composed of cells
(deductive prediction)
Deduction: The IfThen Logic of Hypothesis Based Science
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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 2 or more alternative hypotheses
Failure to falsify a hypothesis does not prove that hypothesis
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)
70
o A controlled experiment compares an
experimental group with a control group
o Ideally, only the variable of interest differs
between the control & experimental groups
o A controlled experiment means that control
groups are used to cancel the effects of
unwanted variables
o A controlled experiment does not mean that
all unwanted variables are kept constant
Designing Controlled Experiments
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A Case Study in Scientific Inquiry:
Investigating Mimicry in Snake
Populations
Many poisonous species are brightly colored, which warns potential predators
Mimics are harmless species that closely resemble poisonous species
Henry Bates hypothesized that this mimicry evolved in harmless species as an evolutionary
adaptation that reduces their chances of being
eaten
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Fig. 1-25
South
Carolina
North
Carolina
Key
Scarlet kingsnake (nonpoisonous)
Scarlet kingsnake (nonpoisonous)
Eastern coral snake (poisonous)
Range of scarlet kingsnake only
Overlapping ranges of scarlet kingsnake and eastern coral snake
74
Field Experiments with
Artificial Snakes
To test this mimicry hypothesis, researchers made hundreds of artificial snakes:
An experimental group resembling kingsnakes
75
Field Experiments with
Artificial Snakes
To test this mimicry hypothesis, researchers made hundreds of artificial snakes:
A control group resembling plain brown snakes
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(b) Brown artificial snake that has been attacked 76
Field Experiments with
Artificial Snakes Equal numbers of both types were placed at field
sites, including areas without poisonous coral
snakes
(a) Artificial kingsnake
77
o After four weeks, the scientists retrieved the
artificial snakes and counted bite or claw marks
o The data fit the predictions of the mimicry
hypothesis: the ringed snakes were attacked
less frequently in the geographic region where
coral snakes were found
o What do you think happened?
78
Fig. 1-27
Artificial
kingsnakes
Brown
artificial
snakes
83% 84%
17% 16%
Coral snakes
absent
Coral snakes
present
Perc
en
t o
f to
tal
att
ack
s
on
art
ific
ial
sna
kes
100
80
60
40
20
0
RESULTS
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Questions That Can and Cannot
Be Addressed by Science o A hypothesis must be
testable and falsifiable
o For example, a
hypothesis that ghosts
fooled with the
flashlight cannot be
tested
o Supernatural and religious
explanations are outside the
bounds of science
Theories in Science
In the context of science, a theory is:
oBroader in scope than a hypothesis
oGeneral, and can lead to new testable
hypotheses
oSupported by a large body of evidence in
comparison to a hypothesis
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81
Building on the Work of Others o Scientists check each
others claims by performing similar
experiments
o It is not unusual for different
scientists to work on the
same research question
o Scientists cooperate by
sharing data about model
organisms (e.g., 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
82
o The combination of science and technology has
dramatic effects on society
o For example, the discovery of DNA by James
Watson and Francis Crick allowed for advances in
DNA technology such as testing for hereditary
diseases
o Ethical issues can arise from new technology, but
have as much to do with politics, economics, and
cultural values as with science and technology
o Many important inventions have occurred where
different cultures and ideas mix
o For example, the printing press relied on
innovations from China (paper and ink) and
Europe (mass production in mills)
o Science benefits from diverse views from different
racial and ethnic groups, and from both women
and men
84
The Value of Diverse Viewpoints in
Science
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Themes That Unify Biology The overarching concepts of this class
1. The Cell-The basic unit of living things
2. Heritable Information- (in the form of DNA) Life continues because the information of How is passed to the next generation
3. Emergent Properties of Biological Systems- With each step up in hierarchy/complexity, properties appear that are not in any components
85
4. Regulation-Feedback mechanisms keep biological systems steady against changes
5. Interaction with the Environment-Living things exchange energy and materials with their environment (non-living & other living things)
6. Energy & Life-Energy is necessary to live, and passes from sunlight (usually) to Producers to Consumers
7. Unity and Diversity-Earth has many, many types of very different living things, but all share basic characteristics, which increase in number with close evolutionary relationships. 86
8. Evolution-Populations adapt to their environments, becoming different (Diversity), but keeping key characteristics (Unity).
9. Structure & Function-Go together at all hierarchical levels.
10. Scientific Inquiry-Science is advanced by observations and testing hypotheses and based on repeatability.
11. Science, Technology, & Society-Are intertwined and inseparable.
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