Introduction to World of Biology

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Introduction to Worldof Biology


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Biology The Study of LifeLife arose morethan 3.5 billionyears agoFirst organisms(living things) weresingle celledOnly life on Earthfor millions ofyearsOrganisms changedover time (evolved)


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New organismsarose from older kinds

Today there aremillions of speciesThey inhabitalmost everyregion of Earthtoday


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Themes of BiologyCell structure andfunctionStability and homeostasis Reproduction andinheritanceEvolution

Interdependence oforganismsMatter, energy, andorganization


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Cell Structure and FunctionCell basic unit of lifeAll organisms aremade of and developfrom cellsSome composed of

only a single cell(unicellular) which isusually identical to

parent


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Cells contain specializedstructures (organelles) that carry out the cellslife processes

Many different kinds ofcells existAll cells surrounded by a

plasma membraneContain a set ofinstructions called DNA

(genetic information)


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Stability and HomeostasisOrganisms must Maintain very stableinternal conditions -

HOMEOSTASISTemperature, water content,chemical content , etc. must be

maintained


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Reproduction and Inheritance

All organisms produce new organismslike themselves REPRODUCE

Organisms transmit hereditaryinformation to their offspringINHERITANCE


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DNAGenetic Information in all cellsDeoxyribonucleic AcidDNA contains instructions fortraits GENESMake the structures andcomplex chemicals necessaryfor life PROTEINSDNA in every body cell(SOMATIC CELLS) is exactly

alike


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Sexual ReproductionHereditary informationfrom two differentorganisms of the samespecies are combinedEgg and spermzygote (fertilized egg)Zygote containshereditary informationfrom both parents


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Asexual ReproductionHereditary informationfrom one, usuallyunicellular, organism that dividesResulting cells containidentical hereditary informationGenetic informationfrom single parent


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EvolutionPopulations of organismschange (evolve ) overgenerations (time)Explains how manydifferent kinds oforganisms came into

existence SPECIESExplains how modern organisms are related topast organisms


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Explains whyorganisms look andbehave the waythey do

Provides a basisfor exploring therelationshipsamong differentgroups oforganisms


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Natural SelectionNatural selection is thedriving force in evolutionOrganisms that have certainfavorable traits are betterable to successfullyreproduce than organismsthat lack these traits


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Natural SelectionSurvival of organisms withfavorable traits cause agradual change in populationsover many generationsAlso Called Survival of theFittest


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Interdependence of OrganismsInteraction oforganisms with oneanother and withtheir environmentECOLOGYInsects depend andflowers DEPEND oneach other for food &pollinationCOEVOLUTION


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All organisms need substances suchas nutrients, water, and gases fromthe environmentThe stability of the environment depends on the healthy functioning oforganisms in that environment


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Matter, Energy andOrganization

Living things are highly organizedRequire a constant supply of energy to maintain their orderly state


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EnergyALL energy comes from the SUN (directly or indirectly)Photosynthesis is the process bywhich some organisms capture theenergy from the sun (solar) andtransform it into energy (chemical)

that can be used by living things


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AutotrophsOrganisms that make theirown food are calledautotrophsPhototrophs use solarenergy (photosynthesis) toget energyConvert H2O and CO 2 into

sugar and O2Chemotrophs use differentchemical processes to getenergy


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HeterotrophsOrganisms that must take infood to meet their energyneeds are called heterotrophs Consume autotrophs(herbivores), otherheterotrophs (carnivores) orboth (omnivores) for theirenergy needsComplex chemicals are brokendown and reassembled intochemicals and structuresneeded by organisms


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The World of Biology


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Characteristics of Life


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CellsAll living things arecomposed of cellsIn multicellularorganisms, many arespecialized to performspecific functionsCells are always verysmallThe size of multi-celled organismsdepends on the numberof cells NOT their size


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OrganizationOrganized at both themolecular and cellular

levelsTake in substancesfrom the environmentand organize them in

complex waysSpecific cellstructures (organelles)carry out particular

functions


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In multicellular

organisms, cellsand groups ofcells (tissues) areorganized bytheir function

Cells tissuesTissues

organsOrganssystemsSystems ORGANISM


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Energy UseUse energy in a process called metabolism

Sum of all chemical processesRequire energy to maintain their molecularand cellular organization, grow andreproduce


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HomeostasisMaintain stable internal conditionsTemperature, pH, etc.


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GrowthGrow occurs as the result of celldivision and cell enlargementCell division is the formation of twocells from a preexisting cellNew cells enlarge as they matureWhen a cell grows to a size whereits surface area isnt big enoughfor its volume , the cell divides


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The process by which an adult organismarise is called development

Repeated cell divisions and celldifferentiation

Development


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ReproductionAll species have the ability to reproduce

Not essential to survival of individualbut is essential for continuation of aspecies


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EvolveAbility to adapt to their environmentthrough the process of evolution

Favorable characteristics are selected forand passed on to offspringCalled adaptations

Driven by natural selectionor survival of the fittest


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Scientific Method


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Observation STEP 1Employing your five senses toperceive objects or events


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Asking a QuestionBased on observations; one or morequestions are generated


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Forming a Hypothesis STEP 2A statement is testable if evidence can becollected that either does or doesntsupport itIt can never be proven beyond doubtOften must be refined and revised ordiscarded


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The Hypothesis ---Is a statement made in advancethat states the results that will

be obtained from testing thehypothesisOften written in the form of anif- then statement


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Experimenting STEP 3Testing a hypothesis or prediction bygathering data under controlled conditions conducting a controlled experiment

Based on a comparison of a controlgroup with an experimental group


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Both groups are identical except for

one factor ( independent variable )Observations and measurements aretaken for a particular factor(dependent variable ) in both groups

Driven by or results from independentvariable


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MeasuringInvolves quantitative data that canbe measured in numbers &/orqualitative data information that

isnt numbers Sampling

Technique of using a sample asmall part to represent theentire population


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Organizing Data STEP 4Involves placing observations andmeasurement (data) in order

Graphs, charts, tables, or maps


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Analyzing Data STEP 4 cont)Collected and organized data must beanalyzed

Process of determining whether data

are reliable or whether they support ordo not support a hypothesis orprediction


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Conclusion STEP 5Conclusions are made on thebasis of facts, not observations

Often drawn from datagathered from a study orexperimentShould support thehypothesisShould be re-testable


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Communication STEP 6Scientists must share the results oftheir studies with other scientists(peers)Publish findings in journalsPresent their findings at scientificmeetings

Scientists must be unbiasedShould not tamper with their dataOnly publish & report tested & provenideas


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CommunicationSharing of information is essential toscientific processSubject to examination and verification by other scientistsAllows scientists to build on the work of

others


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Theories

A theory may be formedafter many relatedhypotheses have beentested and supported with

experimental evidenceA broad and comprehensivestatement of what isthought to be true

Supported by considerableevidenceTies together relatedhypotheses


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LawsA Statement of fact that conciselyexplains an action or group of

actionse.g. Law of GravityAccepted to be true

UniversalMay be expressed as a mathequation

e.g. E=mc2

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MICROSCOPES

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Microscopy and MeasurementMicroscopes produce an enlarged imageof an object

Used to study organisms, cells, and cellpartsIncrease in apparent size is calledmagnification

The ability to show details clearly iscalled resolutionMicroscopes vary in both magnificationand resolution


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Compound Light MicroscopesSpecimen mounted ona glass slideMust be thinly slicedor very smallPair of lenses

Ocular lens (eyepiece)Objective lens(nose piece)

Can be used tostudy LIVEspecimens


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Magnification determined by multiplyingpower of both lensesEyepiece 10X times Objective power (20X,40X)

Highest Maximum magnification is around1000X


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Electron Microscope

Transmission EM (TEM)Uses a beam of electronsto produce an enlargedimage of very thinlysliced specimen on screenor photographic plateImage focused by

magnetic lenses200,000X magnificationCannot be used to viewliving specimens


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Scanning EM (SEM)

3D imageSpecimens not slicedfor viewingSurface sprayed withfine metal coatingAlso uses electronbeam and fluorescentscreen or photographicplates100,000X magnificationCannot be used to viewliving specimens


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MEASUREMENTS

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MeasurementsWe will be using SI units or metricsystem when possible --- the WHOLEworld uses it except us (USA)


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Introduction to World of Biology

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