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1、-Biology:The Science of Our LivesBiology:The Science of Our LivesBiology literally means the study of life.Biology is such aBiology literally means the study of life.Biology is such abroad field,covering the minute workings of chemical machinesbroad field,covering the minute workings of chemical mac
2、hinesinsideinside ourour cells,cells,toto broadbroad scalescale conceptsconcepts ofof ecosystemsecosystems andand globalglobalclimateclimate change.change.BiologistsBiologists studystudy detailsdetails ofof thethe humanhuman brain,brain,thethecomposition of our genes,and even the functioning of ourc
3、omposition of our genes,and even the functioning of ourreproductive system.Biologists recently all but completed thereproductive system.Biologists recently all but completed thedecipheringdeciphering ofof thethe humanhuman genome,genome,thethe sequencesequence ofof deoxyribonucleicdeoxyribonucleicac
4、id(DNA)bases that may determine much of our innateacid(DNA)bases that may determine much of our innatecapabilitiescapabilities andand predispositionspredispositions toto certaincertain formsforms ofof behaviorbehavior andandillnesses.DNA sequences have played major roles in criminalillnesses.DNA seq
5、uences have played major roles in criminalcases(O.J.Simpson,as well as the reversal of death penaltiescases(O.J.Simpson,as well as the reversal of death penaltiesfor many wrongfully convicted individuals),as well as thefor many wrongfully convicted individuals),as well as theimpeachmentimpeachment o
6、fof PresidentPresident ClintonClinton(the(the stainstain atat leastleast diddid notnot lie).lie).WeWe areare bombardedbombarded withwith headlinesheadlines aboutabout possiblepossible healthhealth risksrisks fromfromfavorite foods(Chinese,Mexican,hamburgers,etc.)as well asfavorite foods(Chinese,Mexi
7、can,hamburgers,etc.)as well asthe potential benefits of eating other foods such as cookedthe potential benefits of eating other foods such as cookedtomatoes.Informercials tout the benefits oftomatoes.Informercials tout the benefits ofmetabolism-adjusting drugs for weight loss.Many Americans aremetab
8、olism-adjusting drugs for weight loss.Many Americans areturningturning toto herbalherbal remediesremedies toto easeease arthritisarthritis pain,pain,improveimprove memory,memory,as well as improve our moods.as well as improve our moods.-Can a biology book give you the answers to these questions?No,C
9、an a biology book give you the answers to these questions?No,but it will enable you learn how to sift through the biases ofbut it will enable you learn how to sift through the biases ofinvestigators,the press,and others in a quest to criticallyinvestigators,the press,and others in a quest to critica
10、llyevaluate the question.To be honest,five years after you areevaluate the question.To be honest,five years after you arethroughthrough withwith thisthis classclass itit isis doubtfuldoubtful youyou wouldwould rememberremember allall thethedetails of meatbolism.However,you will know where to look an
11、ddetails of meatbolism.However,you will know where to look andmaybe a little about the process of science that will allow youmaybe a little about the process of science that will allow youto make an informed decision.Will you be a scientist?Yes,into make an informed decision.Will you be a scientist?
12、Yes,ina way.You may not be formally trained as a science major,buta way.You may not be formally trained as a science major,butyouyou cancan thinkthink critically,critically,solvesolve problems,problems,andand havehave somesome ideaidea aboutaboutwhat science can and cannot do.I hope you will be able
13、 to tellwhat science can and cannot do.I hope you will be able to tellthe shoe from the shinola.the shoe from the shinola.Science and the Scientific MethodScience and the Scientific MethodScience is an objective,logical,and repeatable attempt toScience is an objective,logical,and repeatable attempt
14、tounderstand the principles and forces operating in the naturalunderstand the principles and forces operating in the naturaluniverse.universe.ScienceScience isis fromfrom thethe LatinLatin word,word,scientiascientia,toto know.know.GoodGoodscience is not dogmatic,but should be viewed as an ongoingsci
15、ence is not dogmatic,but should be viewed as an ongoingprocessprocess ofof testingtesting andand evaluation.evaluation.OneOne ofof thethe hoped-forhoped-for benefitsbenefitsofof studentsstudents takingtaking a a biologybiology coursecourse isis thatthat theythey willwill becomebecome moremorefamilia
16、r with the process of science.familiar with the process of science.-Humans seem innately interested in the world we live in.Youngchildren drive their parents batty with constant why questions.Science is a means to get some of those whys answered.When weshop for groceries,we are conducting a kind of
17、scientificexperiment.If you like Brand X of soup,and Brand Y is on sale,perhaps you try Brand Y.If you like it you may buy it again,evenwhen it is not on sale.If you did not like Brand Y,then no salewill get you to try it again.In order to conduct science,one must know the rules of the game(imagine
18、playing Monopoly and having to discover the rules as youplay!Which is precisely what one does with some computer orvideogames(before buying the cheatbook).The scientific methodis to be used as a guide that can be modified.In some sciences,such as taxonomy and certain types of geology,laboratoryexper
19、iments are not necessarily performed.Instead,afterformulating a hypothesis,additional observations and/orcollections are made from different localities.Steps in the scientific method commonly include:1.Observation:defining the problem you wish to explain.2.Hypothesis:one or more falsifiable explanat
20、ions for theobservation.-3.Experimentation:Controlled attempts to test one or morehypotheses.4.Conclusion:was the hypothesis supported or not?After thisstep the hypothesis is either modified or rejected,whichcauses a repeat of the steps above.After a hypothesis has been repeatedly tested,a hierarchy
21、 ofscientific thought develops.Hypothesis is the most common,withthe lowest level of certainty.A theory is a hypothesis that hasbeen repeatedly tested with little modification,e.g.The Theoryof Evolution.A Law is one of the fundamental underlyingprinciples of how the Universe is organized,e.g.The Law
22、s ofThermodynamics,Newtons Law of Gravity.Science uses the wordtheory differently than it is used in the general population.Theory to most people,in general nonscientific use,is anuntested idea.Scientists call this a hypothesis.Scientific experiments are also concerned with isolating thevariables.A
23、good science experiment does not simultaneously testseveral variables,but rather a single variable that can bemeasured against a control.Scientific controlled experiments aresituations where all factors are the same between two testsubjects,except for the single experimental variable.-Consider a com
24、monly conducted science fair experiment.Sandywants to test the effect of gangsta rap music on pea plant growth.She plays loud rap music 24 hours a day to a series of pea plantsgrown under light,and watered every day.At the end of herexperiment she concludes gangsta rap is conducive to plant growth.H
25、er teacher grades her project very low,citing the lack of acontrol group for the experiment.Sandy returns to her experiment,but this time she has a separate group of plants under the sameconditions as the rapping plants,but with soothing Led Zeppelinsongs playing.She comes to the same conclusion as
26、before,butnow has a basis for comparison.Her teacher gives her project abetter grade.Theories Contributing to Modern BiologyModern biology is based on several great ideas,or theories:1.The Cell Theory2.The Theory of Evolution by Natural Selection3.Gene Theory4.Homeostasis-Robert Hooke(1635-1703),one
27、 of the first scientists to use amicroscope to examine pond water,cork and other things,referredto the cavities he saw in cork as cells,Latin for chambers.Mattias Schleiden(in 1838)concluded all plant tissues consistedof cells.In 1839,Theodore Schwann cameto a similar conclusionfor animal tissues.Ru
28、dolf Virchow,in 1858,combined the twoideas and added that all cells come from pre-existing cells,formulating the Cell Theory.Thus there is a chain-of-existenceextending from your cells back to the earliest cells,over 3.5billion years ago.The celltheory states that all organisms arecomposed of one or
29、 more cells,and that those cells have arisenfrom pre-existing cells.Figure 1.James Watson(L)and Francis Crick(R),andthe model they built of thestructure ofdeoxyribonucleic acid,DNA.While a model may seema small thing,theirdevelopment of the DNAmodel fostered increasedunderstanding of how geneswork.I
30、mage from theInternet.In 1953,American scientist James Watson and British scientistFrancis Crick developed the model for deoxyribonucleic acid(DNA),a chemical that had(then)recently been deduced to be the physical-carrier of inheritance.Crick hypothesized the mechanism for DNAreplication and further
31、 linked DNA to proteins,an idea sincereferred to as the central dogma.Information from DNA languageis converted into RNA(ribonucleic acid)language and then tothe language of proteins.The central dogma explains theinfluence of heredity(DNA)on the organism(proteins).Homeostasis is the maintainence of
32、a dynamic range of conditionswithin which the organism can function.Temperature,pH,andenergy are major components of this concept.Theromodynamics isa field of study that covers the laws governing energy transfers,and thus the basis for life on earth.Two major laws are known:the conservation of matte
33、r and energy,and entropy.These willbe discussed in more detail in a later chapter.The universe iscomposed of two things:matter(atoms,etc.)and energy.These first three theories are very accepted by scientists andthe general public.The theory of evolution is well accepted byscientists and most of the
34、general public.However,it remainsa lightening rod for school boards,politicians,and televisionpreachers.Much of this confusion results from what the theorysays and what it does not say.Development of the Theory of Evolution-Modern biology is based on several unifying themes,such as thecell theory,ge
35、netics and inheritance,Francis Cricks centraldogma of information flow,and Darwin and Wallaces theory ofevolution by natural selection.In this first unit we will examinethese themes and the nature of science.The Ancient Greek philosopher Anaxiamander(611-547 B.C.)and theRoman philosopher Lucretius(9
36、9-55 B.C.)coined the concept thatall living things were related and that they had changed over time.The classical science of their time was observational rather thanexperimental.Another ancient Greek philosopher,Aristotledeveloped hisScala Naturae,or Ladder of Life,to explain hisconcept of the advan
37、cement of living things from inanimate matterto plants,then animals and finally man.This concept of man asthe crown of creation still plagues modern evolutionarybiologists(See Gould,1989,for a more detailed discussion).Post-Aristotlean scientists were constrained by the prevailingthought patterns of
38、 the Middle Ages-the inerrancy of thebiblical book of Genesis and the special creation of the worldin a literal six days of the 24-hour variety.Archbishop JamesUssher of Ireland,in the late 1600s calculated the age of theearth based on the geneologies from Adam and Eve listed in the-biblical book of
39、 Genesis.According to Usshers calculations,theearth was formed on October 22,4004 B.C.These calculations werepart of Usshers book,History of the World.The chronology hedeveloped was taken as factual,and was even printed in the frontpages of bibles.Usshers ideas were readily accepted,in partbecause t
40、hey posed no threat to the social order of the times;comfortable ideas that would not upset the linked applecarts ofchurch and state.Figure 2.Archbishop JamesUssher.Image from the Internet.Often new ideas must come out of left field,appearing as wildnotions,but in many cases prompting investigation
41、which may laterreveal the truth.Usshers ideas were comfortable,the Biblewas viewed as correct,therefore the earth must be only 5000 yearsold.Geologists had for some time doubted the truth of a 5,000 yearold earth.Leonardo da Vinci(painter of the Last Supper,and the-Mona Lisa,architect and engineer)c
42、alculated the sedimentationrates in the Po River of Italy.Da Vinci concluded it took 200,000years to form some nearby rock deposits.Galileo,convictedheretic for his contention that the Earth was not the center ofthe Universe,studied fossils(evidence of past life)andconcluded that they were real and
43、not inanimate artifacts.JamesHutton,regarded as the Father of modern geology,developed theTheory of Uniformitarianism,the basis of modern geology andpaleontology.According to Huttons work,certain geologicalprocesses operated in the past in much the same fashion as theydo today,with minor exceptions
44、of rates,etc.Thus manygeological structures and processes cannot be explained if theearth was only a mere 5000 years old.The Modern View of the Age of the EarthRadiometric age assignments based on the rates of decay ofradioactive isotopes,not discovered until the late 19th century,suggest the earth
45、is over 4.5 billion years old.The Earth isthought older than 4.5 billion years,with the oldest known rocksbeing 3.96 billion years old.Geologic time divides into eons,eroas,and smaller units.An overview of geologic time may beobtained at.-Figure 3.The geologic time scale,hilighting some of the firsts in the evolutionof life.One way to represent geological time.Note the break during the precambrian.If the vertical scale was truly to scale the precambrian would account for 7/8 ofthe graphic.-