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    Introductionntroductionto Biologyo Biology

    The World of Biology

    Chapter 1.2

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    Biologyiology The Study of Lifehe Study of Life

    New organisms arose from older kinds Today there are millions of species They inhabit almost every region of Earth today

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    Themes of BiologyThemes of Biology

    Cell structure and function Stability and homeostasis Reproduction and

    inheritance Evolution Interdependence of

    organisms Matter, energy, and

    organization

    Cell Structure and FunctionCell Structure and Function

    Cell basic unit of life All organisms are made of and

    develop from cells Some composed of only a

    single cell ( unicellular ) which isusually identical to parent

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    Cells Most organisms are

    composed of many cells(multicellular ) Cells are different

    (undergo differentiation ) Cells are small

    Cells are highly organized

    Cells contain specializedstructures ( organelles ) thatcarry out the cells lifeprocesses

    Many different kinds of cellsexist

    All cells surrounded by aplasma membrane

    Contain a set of instructionscalled DNA (geneticinformation )

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    Stability and Homeostasis Organisms must Maintain very stable

    internal conditions - HOMEOSTASIS Temperature, water content, chemical

    content, etc. must be maintained

    Reproduction and Inheritance

    All organisms produce new organismslike themselves REPRODUCE

    Organisms transmit hereditaryinformation to their offspringINHERITANCE

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    DNADNA Genetic Information in all cells Deoxyribonucleic Acid DNA contains instructions for traits

    GENES Make the structures and complex

    chemicals necessary for life

    Reproductioneproduction

    All species have the ability to reproduceability to reproduce Not essential to survival of individualNot essential to survival of individual but

    is essential for continuation of a species

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    Sexual ReproductionSexual Reproduction Hereditary information from

    two different organisms of thesame species are combined

    Egg and sperm zygote(fertilized egg)

    Zygote contains hereditaryinformation from both parents

    Asexual ReproductionAsexual Reproduction Hereditary information

    from one, usuallyunicellular, organism thatdivides ( binary fission)

    Resulting cells containidentical hereditaryinformation

    Genetic information fromsingle parent

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    Matter, Energy and Organization Living things are highly organized Require a constant supply of energy to

    maintain their orderly state

    In multicellularmulticellularorganisms,organisms, cells andgroups of cells(tissues) areorganized by theirfunction CellsCells tissues TissuesTissues organs OrgansOrgans

    systemssystems SystemsSystems ORGANISMORGANISM

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    Energy Use Use energy in a process called metabolismmetabolism

    Sum of all chemical processes Sum of all chemical processes Require energy to maintain their molecular

    and cellular organization, grow andreproduce

    Energy ALL energy comes from the SUN (directly

    or indirectly) Photosynthesis is the process by which

    some organisms capture the energy fromthe sun (solar) and transform it into energy(chemical) that can be used by livingthings

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    AutotrophsAutotrophs Organisms that make their

    own food are calledautotrophs

    Phototrophs use solarenergy (photosynthesis) toget energy

    Convert H 2O and CO 2 intosugar and O2

    Chemotrophs use differentchemical processes to getenergy

    HeterotrophsHeterotrophs Organisms that must take in food to meet

    their energy needs are called heterotrophsheterotrophsConsume autotrophs ( (herbivoresherbivores ),), otherheterotrophs ( (carnivorescarnivores )) or both((omnivoresomnivores )) for their energy needs

    Complex chemicals are broken down andreassembled into chemicalsreassembled into chemicals and structuresneeded by organisms

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    EvolutionEvolution Populations of organisms

    change (evolve) overgenerations (time)

    Explains how many differentkinds of organisms cameinto existence SPECIES

    Explains how modernorganisms are related topast organisms

    Explains whyorganisms look andbehave the way theydo

    Provides a basis forexploring therelationships amongdifferent groups oforganisms

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    Evolve

    Ability to adapt to their environment through theprocess of evolutionevolution

    Favorable characteristicsFavorable characteristics are selected for andpassed on to offspring

    Called adaptationsadaptations Driven byDriven by

    natural selectionnatural selectionor survival of theor survival of thefittestfittest

    Natural SelectionNatural Selection

    Natural selection is the drivingforce in evolution

    Organisms that have certainfavorable traits are better ableto successfully reproduce thanorganisms that lack these traits

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    Natural SelectionNatural Selection

    Survival of organisms withfavorable traits cause a gradualchange in populations overmany generations

    Also Called Survival of theFittest

    Interdependence ofOrganisms

    Interaction of organismswith one another andwith their environmentECOLOGY

    Insects depend andflowers DEPEND oneach other for food &pollinationCOEVOLUTION

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    All organisms need substances suchas nutrients, water, and gases from theenvironment

    The stability of the environmentdepends on the healthy functioning oforganisms in that environment

    Responsiveness Respond to stimuliRespond to stimuli in the

    external environment

    Detect and respond tochanges in light, heat,light, heat,sound and chemical andsound and chemical andmechanical contactmechanical contact

    Coordinates itsresponses

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    Scientific MethodChapter 1.3

    ObservationObservation STEP 1STEP 1

    Employing your five sensesfive senses toperceive objects or events

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    Asking a Question Based on observations; one or more

    questions are generated

    Forming a Hypothesis STEP 2

    A statement is testabletestable if evidence can becollected that either does or doesnt supportit

    It can never be proven beyond doubt Often must be refined and revised orrefined and revised or

    discardeddiscarded

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    The HypothesisThe Hypothesis --- ---

    Is a statement made in advanceIs a statement made in advancethat states the results that will bethat states the results that will beobtained from testing theobtained from testing thehypothesishypothesis

    Often written in the form of an ifif--thenthen statement statement

    Experimenting STEP 3

    Testing a hypothesis or prediction by gatheringdata under controlled conditions conducting acontrolled experiment Based on a comparison of a control group

    with an experimental group

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    Measuring Involves quantitative dataquantitative data that can

    be measured in numbersnumbers &/orqualitative dataqualitative data information thatisnt numbers

    Sampling

    Technique of using a samplesample asmall part to represent the entirerepresent the entirepopulationpopulation

    Organizing Data STEP 4

    Involves placing observations andmeasurement (data) in order Graphs, charts, tables, or mapsGraphs, charts, tables, or maps

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    Analyzing Data STEP 4 cont) Collected and organized data must be analyzed

    Process of determining whether data aredetermining whether data arereliable or whether they support or do notreliable or whether they support or do notsupport a hypothesissupport a hypothesis or prediction

    Conclusion STEP 5

    Conclusions are made on the basisof facts, not observations

    drawn from data gathered from astudy or experiment Should support the hypothesis Should be re-testable

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    Communication STEP 6

    Scientists must share the results of theirshare the results of theirstudiesstudies with other scientists (peers)

    PublishPublish findings in journals journals Present their findings at scientific meetingsscientific meetings Scientists must be unbiasedunbiased

    Should not tamper with their data Only publish & report tested & proven ideas

    CommunicationCommunication

    Sharing of informationSharing of information is essential to scientificprocess

    Subject to examination and verificationverification byother scientists

    Allows scientists to build on the work ofothers

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    TheoriesTheories A theorytheory may be formed

    after many relatedhypotheses have beentested and supported withexperimental evidence

    A broad and comprehensivebroad and comprehensivestatement of what is thoughtstatement of what is thoughtto be trueto be true

    Supported by considerableconsiderableevidenceevidence

    Ties together relatedhypotheses

    LawsLaws

    A Statement of fact that conciselyA Statement of fact that conciselyexplains an action or group of actionsexplains an action or group of actionse.g. Law of Gravitye.g. Law of Gravity

    Accepted to be trueAccepted to be true UniversalUniversal