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Chapter One
Introduction: Themes inthe Study of Life
I nstructor : Beverly Cochran
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What is Biology?
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Biologyisthescienceoflife
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Traditionally divided into three divisions:
- Botany- Zoology (NOT Zoo-ology!)
- Microbiology
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Modern Biology
Many diversesubdivisions, such as:
- Wildlife Biology
- Cellular Biology
- Anatomy & Physiology
- Ecology- Genetics
- Evolutionary Biology
- Molecular Biology
- Developmental Biology- Immunology
- Behavioral Ecology
- Marine Biology
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There are two main types
of biologists . . .
- Laboratory
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- Field
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- asking questions and seeking science-based answers
The central activity of biology: scientific inquiry
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Biologists ask questions suchas:
- how a single cell develops intoan organism
- how the human mind works
- how living things interact incommunities
Biology is therefore a quest an ongoing inquiry about the
nature of life
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How do we define life?
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Order
Evolutionaryadaptation
Responseto theenvironment
Reproduction
Growth anddevelopment
Energyprocessing
Regulation
Character istics of l ife
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1) Order
living things arehighly organizedstructures made up
of cells
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2) Evolutionaryadaptation
adaptations that evolve
over many generations bythe reproductive success ofthose individuals with
heritable traits that arebest suited for theirenvironment
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3) Response to theenvironment
all living things cansense theirenvironment and
react to it
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4) Reproduction
all living thingsreproduce
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5) Growth and development
all living things inherit information (carried bygenes) that control the pattern of growth and
development
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6) Energy processing
all organismsneed energy forall life activities;plants get energythroughphotosynthesis,and animals getenergy fromcellularrespiration
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7) Regulation
all living thingscarry outhomeostatsis(maintaining astable, constantinternaltemperature)
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There are seven themes that connect theconcepts of Biology:
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Theme 1 : New properties emerge at each level in thebiological hierarchy
Life can be studied at different levelsfrom molecules to the entire livingplanet
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1) THE BIOSPHERE
10) molecules
The study of life can therefore be divided into different levels ofbiological organization, from largest (biosphere) to smallest(molecules)
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1) The Biosphere consists of all of the environmentson Earth that are inhabited with life
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2) Ecosystems consists ofall living things andnonliving components in aparticular area
- soil, water, light,atmospheric gases
http://www.marietta.edu/~biol/biomes/Prickly%20Pear%20(Opuntia%20sp.) -
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3) Communities
All of the organisms
that live in a particularecosystem; plants,animals, fungi,microorganisms, etc.
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4) Populations
consists of all of theindividuals of aspecies living withinan area
- e.g., all of the white-taileddeer ( Odocoileus virginianus )
in a certain forest in East Texas- e.g., all of the striped skunks(M ephitis mephitis ) in
Commerce, TX
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5) Organisms every individualliving thing
- each tree in a forest
- each squirrel
- each microbeActinomyces
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6) Organs and Organ Systems
Organs : body parts consisting oftwo or more tissues that carry out aparticular function in the body
Ex: heart, kidneys, brain
Organ System : team of organs
that work together for a specificfunction
Ex: tongue, stomach, intestines,
etc. = Digestive System
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7) Tissues integrated groups ofcells with a common
function, structure, orboth
e.g., different types of
muscle cells make updifferent muscle tissue
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9) Organelles
any of several membrane-enclosed structures withspecialized functions,
suspended in the cytosol ofeukaryotic cells
e.g., mitochondria, nucleus,
etc.
Nucl eus
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10) Molecules
Chemical structure consisting of two or more smallchemical units called atoms
e.g., H 2O the water molecule
Biologists can use reductionism
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Biologists can use reductionismto understand complexsystems
Reductionism is the reduction ofcomplex systems to simplercomponents that are moremanageable to study
e.g., studying just themolecular structure ofDNA
Reductionism is useful however!
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Reductionism is useful however!
Biologists must balance the reductionist strategy with the larger-scale understanding
- how parts of cells, organisms, ecosystems, etc. work together
This is called Systems Biology
A system is a combination of components that function together
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A system is a combination of components that function together
Systems biology constructs models for the dynamic behavior ofwhole biological systems
The systems approach poses questions such as:
- How does a drug for blood pressure affect other organs?
- How does increasing CO 2 alter the biosphere?
Theme2 : Organisms interact with other organisms and their
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Theme 2 : Organisms interact with other organisms and theirenvironments
Every organism interacts with the living and the nonliving parts
of their environment
- both organisms and their environments are affected by theseinteractions
e.g., a tree takes up water and minerals from the soil and carbondioxide from the air; the tree releases oxygen to the air androots help form soil
#1
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The in teraction betweenorgani sms and theirenvir onment is cal ledEcosystem Dynamics
The dynamics of anecosystem include twomajor processes:
1) The flow of energy fromsunlight to producers toconsumers
2) Cycling of nutrients, in
which materialsacquired by plantseventually return to thesoil
Sunlight
Ecosystem
Heat
Heat
Cyclingof
chemicalnutrients
Producers(plants and other
photosyntheticorganisms)
Chemical energy
Consumers(such as animals)
#1
#2
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Theme 3 : All of the activities of life require energy transfer andtransformation
e.g., light, chemical, kinetic, or thermal
Energy flows through an ecosystem, usually entering as light andexiting as heat
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Theme 4 : Structure and functionare correlated at all levels ofbiological organization
Structure and function of living organisms are closelyrelated
e.g., a leaf is thin and flat, maximizing the capture of
light by chloroplasts
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Example: The structures of birds function to enablethem to f ly
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Structures that function for flight:
1) Shape of the bird and its wings extremelyaerodynamic!
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2) Skeleton and hollow bones makes the bird very light, strutsmake bones strong
3) Feathers flight feathers
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3) Feathers flight feathers
Primaries: long and stiff, allow forthrust (flapping flight)
Secondaries: tightly overlapping, allowfor lift
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Theme 5 : Cells are an organisms
basic unit of structure andfunction
The cell is the lowest level of organization that can
perform all activities required for life
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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
A eukaryotic cell has membrane-enclosed organelles
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y g
- largest is usually the nucleus
e.g., plants, animals, fungi, etc.
A prokaryotic cell is simpler and usually smaller
- no nucleus or other membrane-enclosed organelles
e.g., bacteria and Archaea
Theme 6 : The continuity of life is based on heritable information
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yin the form of DNA
Chromosomes contain most of acells genetic material in theform of DNA(deoxyribonucleic acid)
Chromosomes contain genes madeof DNA
- genes are the units of inheritancethat transmit information fromparents to offspring
Chr omosome
http://upload.wikimedia.org/wikipedia/commons/0/07/Gene.pnghttp://upload.wikimedia.org/wikipedia/commons/0/07/Gene.png -
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Each chromosome has one long DNAmolecule with hundreds or thousandsof genes
Inherited DNA directs the development of an organism
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NucleicontainingDNA
Sperm cell
Egg cell
Fertilized eggwith DNA fromboth parents
Embryos cells with copies of inherited DNA
Offspring with traitsinherited fromboth parents
DNA
Inherited DNA directs the development of an organism
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Each link of a chain is one offour kinds of chemicalbuilding blocks callednucleotides
Each DNA molecule is made upof two long chains arranged in
a double helix
Nucleus
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Nucleus DNA
Cell
Nucleotide
(a) DNA double helix (b) Single strand of DNA
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DNA in genes also control protein
productionWhy are proteins important?
Proteins are essential parts of organisms and participate in everyprocess within cells
Many proteins are enzymes that catalyze (speed up) biochemicalreactions and are vital to metabolism
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Theme 7 : Feedback mechanismsregulate biological systems
Feedback mechanisms allow biological processes to self-regulate
1) Negative feedback a change in a physiological variable triggers aresponse that counteracts the initial fluctuation
2) Positive feedback a change in a physiological variable triggers
mechanisms that amplify the change
Negative feedback:
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Like a thermostat in the home: as the temperature rises (above theideal normal temperature), the thermostat detects the change andtriggers the air-conditioning to turn on and cool the house.
Once the temperature reaches its thermostat setting, the airconditioning turns off.
P iti f db k
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Positive feedback:
The onset of contractions in childbirth: when a contraction occurs,the hormone oxytocin is released into the body, which stimulatesfurther contractions.
This results in contractions increasing in amplitude and frequency.
The Core Theme in Biology: Evolution is the fundamental
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organizing principle of biology
Biological evolution is the scientific explanation for all unity and
diversity on Earth- organisms on Earth today are the modified descendants of
common ancestors
TheCoreTheme : Evolution accounts for the unity
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The Core Theme : Evolution accounts for the unityand diversity of life
Biologists agree the most importanttheme of all
Nothing in biology makes sense exceptin the light of evolution
Evolution unifies all of biologythroughout the history of life on Earth
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Grouping Species: The Basic Idea
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Taxonomy is the branch of biology that names and classifies
species into groups of increasing sizeDomains, followed by kingdoms, are the broadest units of
classification
Species Genus Family Order Class Phylum Kingdom Domain
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Ur sus americanus (American black bear)
Ursus
Ursidae
Carnivora
Mammalia
Chordata
Animalia
Eukarya
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( ) DOMAIN BACTERIA h di d id d f h
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(a) DOMAIN BACTERIA the most diverse and widespread of theprokaryotes
- there are approximately ten times as many bacterial cells in thehuman body as there are human cells in the body
e.g., Staphylococcus spp., Lactobacillus spp., Streptomyces spp.
E. coli
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(b) DOMAIN ARCHAEA - prokaryotes that live in extremeenvironments, such as salt lakes and boiling hot springs (sometimescalled extremophiles); believed to be the oldest organisms on Earth
http://www.ucmp.berkeley.edu/archaea/KOSmethanococcus.jpghttp://www.ucmp.berkeley.edu/archaea/NIJmethanosarcina.gifhttp://www.ucmp.berkeley.edu/archaea/NIJmethanobac.gif -
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Protists are in multiple kingdoms; unicellular eukaryotes and theirl i l i l l i ll l l i
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relatively simple multicellular relatives
e.g., Amoebas, Euglena (unicellular animal-like protists); Algae(multicellular plant-like protists)
d b b f d
http://en.wikipedia.org/wiki/Image:Laurencia.jpghttp://upload.wikimedia.org/wikipedia/commons/8/88/Euglena_EPA.jpghttp://en.wikipedia.org/wiki/Image:Chaos_diffluens.jpg -
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Kindom Fungi absorb nutrients after decomposing organic matter(leaf litter, animal feces)
Kingdom Plantae consists of multicellular eukaryotes
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that carry out photosynthesis
convert light energy into the chemical energy in food
Kingdom Animalia consists of multicellular
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Kingdom Animalia consists of multicellulareukaryotes that ingest other organisms
I n all of thi s diversity there is unity!
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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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Cilia ofParamecium
Cross section of a cilium, as viewedwith an electron microscope
Cilia of tracheacells
CharlesDar inandtheTheor of
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Charles Darwin and the Theory ofNatur al Selection explain diversity anduni ty in li fe
Fossils and other evidence document theevolution of life on Earth over billions ofyears
Charles Darwin published On the Origin of Species by M eans ofN t lS l ti i 1859
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Natural Selection in 1859
Darwin made two main points:
Species showed evidence of descent with modificationfrom common ancestors
Natural selection is the mechanism behind descent with
modification
Darwins theory explained the duality of unity anddiversity
Darwin observed that:
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Individuals in a population have traits that vary
Many of these traits are heritable (passed from parentsto offspring)
More offspring are produced than survive
Competition is inevitable
Species generally suit their environment
Darwin inferred that:
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Individuals that are best suited to their environment aremore likely to survive and reproduce
Because of this, over time, more individuals in a populationwill have the advantageous traits
In other words, the natural environment selects for beneficialtraits
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Natural selection is often evident in adaptations of organisms to theirway of life and environment
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Scientists make observations andthen form and test hypotheses:
Science is a way of knowing
- use inquiry: search forinformation and explanation,focusing on specific questions
Science describes natural structures and processes
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Science describes natural structures and processes
- based on observation and the analysis of data
European black caps
Types of Data
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Data are recorded observations or items of information
Data fall into two categories:
1) Qualitative : descriptions rather than measurements
2) Quanti tative : recorded measurements, sometimes
organized into tables and graphs
FYI the word data is plural, datum is singular!
e.g., The data were collected from 120 nests.
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Qualitative data:
GTGrackle Nestling Data2009 Percentage Male 33.33 Female 66.17
Gender Outcome Mites?
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Date Time Nest Est. Age M=1 F=2MassBird Mass Bag
MassTotal ROP Rtarsus
Dead=1Unknown=2
Yes=1No=2
161 1209 937021 11 2 94.0 16.0 78.0 29.07 33.89
161 1209 937023 10 2 68.0 16.0 52.0 25.34 30.72 1
161 1209 937023 10 2 83.0 16.0 67.0 34.25 33.73
161 1315 938005 10 2 75.0 16.0 59.0 28.42 33.32
161 1315 938005 10 2 101.0 16.0 85.0 25.04 34.84
161 1315 938009 9 2 83.0 17.0 66.0 19.93 29.33161 1315 938009 9 2 73.0 17.0 56.0 27.40 32.12
161 1315 938014 12 2 50.0 18.0 32.0 22.89 26.87 1 1
161 1315 938014 12 2 96.0 18.0 78.0 46.98 37.74 1
161 1315 938014 12 2 91.0 18.0 73.0 41.88 38.92 1
161 1315 938019 12 1 120.0 17.0 103.0 35.66 38.97
161 1315 938019 12 2 59.0 17.0 42.0 26.33 26.46
163 0845 927038 9 1 102.0 17.0 85.0 25.27 35.82
163 0845 927038 9 2 57.0 17.0 40.0 20.77 25.94 1
163 0845 927022 10 1 110.0 17.0 93.0 28.96 37.74
163 0845 927022 10 2 78.0 17.0 61.0 26.32 31.86
163 0845 927044 10 2 66.0 18.0 48.0 19.37 29.21163 0845 927044 10 2 71.0 18.0 53.0 16.18 28.87
163 0845 933049 10 2 76.0 18.0 58.0 24.49 29.90
163 0845 933049 10 2 82.0 17.0 65.0 29.91 32.92
163 0845 937026 9 1 102.0 18.0 84.0 21.56 33.70
163 0845 937026 9 2 63.0 18.0 45.0 18.56 26.40
163 0845 937017 10 2 79.0 17.0 62.0 9.24 27.37
163 0845 937016 9 2 50.0 17.0 33.0 14.19 22.06
163 0845 938026 9 2 40.0 17.0 23.0 9.26 20.64
163 0845 938026 9 1 96.0 17.0 79.0 22.24 32.66
163 0845 938026 9 2 71.0 17.0 54.0 28.41 18.39
166 0900 938012 11 2 103.0 30.0 73.0 39.09 36.33
166 0935 937001 11 2 87.0 30.0 57.0 19.79 30.01
166 0935 937001 11 2 92.0 32.0 60.0 23.27 30.84
166 0935 937008 11 1 94.0 17.0 77.0 25.20 35.32
166 0935 937002 9 2 64.0 30.0 34.0 16.49 26.81 1
166 0935 937002 9 2 53.0 17.0 36.0 16.89 26.00 1
166 0935 937024 10 1 142.0 34.0 108.0 41.99 42.43
166 0935 933055 10 2 81.0 17.0 64.0 26.02 33.05 1
166 0935 933055 10 1 119.0 17.0 102.0 33.34 39.11 1
166 0935 933048 11 1 87.0 17.0 70.0 26.79 34.66
166 0935 933050 10 2 73.0 17.0 56.0 26.73 30.49
166 1430 927030 9 2 62.0 18.0 44.0 25.60 29.62 1
166 1430 927030 9 2 60.0 18.0 42.0 23.53 29.67 1
Quanti tative data:
Forming and testing hypotheses involves explainingnature
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nature
Observations can lead to questions
- questions can lead to hypothetical explanationscalled hypotheses
What is a hypothesis?
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A hypothesis is a tentative answer to a well-framedquestion
A scientific hypothesis leads topredictions
- predictions are tested byobservation or experimentation
For example:
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Observation: Your flashlight doesnt work
Question: Why doesnt your flashlight work?
Hypothesis 1: The batteries are deadHypothesis 2: The bulb is burned out
Both of these hypotheses are testable
The Scientific Method
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The scienti f ic method is an process ofinquiry
Science is based on the textbookscientific method but rarelyfollows all the ordered steps
1) D fi th ti
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1) Define the question
2) Gather information and resources
(observe)
3) Form hypothesis
4) Perform experiment and collect data
5) Analyze data
6) Interpret data and drawconclusions that serve as a starting
point for new hypothesis
7) Publish results
8) Retest (frequently done by otherscientists)
H ow Scienti sts Do I t!
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Limitations of Science
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In science, observations and experimental
results must be repeatableScience cannot support or falsify
supernatural explanations
- outside the bounds of science
Theories in Science
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In the context of science, a theory is different than a hypothesis:
1) Broader in scope than a hypothesis
2) General, and can lead to new testable hypotheses
3) Supported by a large body of evidence in comparison to ahypothesis
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In ordinary speech, "theory" isoften used to mean "guess" or
"hunch"
- in scientific terminology, a theoryis a set of universal statements thatexplain some aspect of the naturalworld
- held with a high degree ofconfidence
- supported by enough physicalevidence and research to make itsabandonment unlikely
Examples of a theories in Biology:
Th C ll Th (1838) ll k li i hi d f
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- The Cell Theory (1838) - all known living things are made up ofcells
- Darwins Theory of Evolution (1859)- Mendels Laws of Inheritance (1865) - transmission of hereditary
characteristics from parent organisms to their children
Robert Hookes cork
cells
Theories are not easily discarded
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New discoveries are first assumedto fit into the existing theory
It is only when, after repeatedexperimental tests, the newphenomenon cannot beaccommodated that scientistsseriously question the theory andattempt to modify it
Scientific theories represent the reality of the physical world
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To say It's only a theory is nave and exhibits a lack ofbasic understanding of science, research, and the scientificmethod
Example :
It is unlikely that a personwill step off a tall building onthe assumption that they willnot fall, because "Gravity isonly a theory."
Science benefits from cooperation
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Most scientists work in teams, which often include graduate and
undergraduate studentsMust share results
- seminars, publications, and websites
Results are subject to peer-review:other biologists review experiment; canonly publish if passes peer-review
Science, Technology, and Society
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The goal of science is to understand natural phenomena
The goal of technology is to apply scientific knowledge for somespecific purpose
Science and technology are interdependent
Biology is marked by discoveries, while technology is markedby inventions
The combination of science and technologyhas dramatic effects on society
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Ethical issues often have as much to do with politics, economics, and culturalvalues as with science and technology
Example : the discovery of DNA by James Watson and FrancisCrick allowed for advances in DNA technology
However, ethical issues can arise:
- Who should have access to personal genetic information, andhow will it be used?
- Should parents have the right to have their minor childrentested for adult-onset diseases?
- What are the larger societal issues raised by newreproductive technologies?
- How does genomic information affect members of minoritycommunities?
Theend
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The end