Note:Theactuallecturecontainscolorimages.Thecolorsfromoneimagearediscussedbytheprofessor.Youdonotneedtoseethecolorstounderstandthelectureortoanswerthequestions.

Grand Canyon How was the Grand Canyon formed? The truth is that no one knows for sure though there are some pretty good guesses, and it is usually thought that a number of processes combined to create the views that you see in today's Grand Canyon. The most powerful force to have an impact on the Grand Canyon is erosion, primarily by water (and ice) and secondly by wind. Other forces that contributed to the Canyon's formation are the course of the Colorado River itself, vulcanism, continental drift and slight variations in the earth's orbit which in turn causes variations in seasons and climate. Water seems to have had the most impact basically because our planet has lots of it and it is always on the move. Many people cannot understand how water can have such a profound impact considering that the Canyon is basically located in a desert. This is one of the biggest reasons that water has such a big impact here. Because the soil in the Grand Canyon is baked by the sun it tends to become very hard and cannot absorb water when the rains come. When it does rain the water tends to come down in torrents which only add to the problem. The plants that grow in the Grand Canyon tend to have very shallow root systems so that they can grab as much water as possible on those rare occasions when it does rain. Unfortunately these root systems do nothing to deter erosion by holding the soil in place. Now you've got lots of water, no place for it to go, but down to the Colorado River, and nothing holding the soil and rock in place. The result is frequently a flash flood roaring down a side canyon that can move boulders the size of automobiles, buses and even small houses. If automobiles, buses and small houses are in the way then it will take them too.(A) [■] Luckily no one builds houses in the Grand Canyon so that's not a problem but there are a few autos, vans and buses sitting at the bottom of the Colorado River. This mass that moves down a side canyon during a flash flood is more like fast flowing concrete than water and it can be very dangerous. You should always be well informed of weather conditions when you are hiking through side canyons in the Grand Canyon.(B) [■] In the colder months, especially on the north rim, water seeps into cracks between the rocks. These cracks can be caused by seismic activity, or by the constant soaking and drying of the rocks.(C) [■] When the water freezes it expands and pushes the rocks apart and widens the cracks. Eventually rocks near the rim are pushed off the edge and fall into the side canyons. These rocks sometimes hit other rocks and are stopped but on occasion one fall by a large rock will cause a cascading effect and create a rock fall that will alter the landscape drastically in the side canyon. Debris from rock falls piles up at the bottom of the side canyons and is then carried down to the Colorado River the next time there is a flash flood. Rock falls frequently take out sections of trail in the Grand Canyon requiring the Park Service to close these trails until they can be repaired.(D) [■] Once the ice has pushed the rocks off the edge and the water in the flash floods has carried them down to the river, then the Colorado itself takes over. The erosive action of the Colorado has been severely constrained by the building of the Glen Canyon Dam, which ended the annual spring floods, but there is still a lot of water flowing relatively quickly through a very narrow gorge. Before building the dam the Colorado River had spring floods that would exceed a flow rate of 100000 CFS (cubic feet per second). All of that snow melting in the Colorado Rockies came pouring down through the Grand Canyon in May and June every year, like clock-work. These spring floods were considerably larger than today's "trickle" of 8000～10000 CFS at low water and even the 20000 CFS peak flow rates.

ListentopartofaconversationbetweenastudentandaclerkintheScholarshipDepartment.Nowgetreadytoanswerthequestions.Youmayuseyournotestohelpyouanswer.

FilmExchangesinAmerica'sEarlyMovieIndustryMotionpictureswereexhibitedtothepublicinthelate1800s,thoughthefirstdevicetoaccomplishthiswouldseemveryunfamiliartotoday'smovie-goingaudiences.ThomasEdison's1893Kinetoscopewaslittlemorethanawoodenboxwithasmallglasswindow.Intendedonlyforindividualviewing,ithousedarolloffilm,amechanicaldevicetocirculatethefilm,andasmalllighttoilluminateit.Apersonwouldpeerthroughthewindowandwatchashortmovingsequence,usuallyjustadepictionofaneverydayeventortheperformanceofanacrobatordancer.Needlesstosay,themedium'sabilitytoserveonlyonecustomeratatimeseverelylimiteditsprofitability.Everythingchangedtwoyearslaterwiththeadventofprojection,bywhichamuchlargerfilmimagecouldbeshowntomultipleviewerssimultaneously.TheLumierebrothersofFrancewerethefirsttointroducethisnewtechnologywithaprojectionmachinecalledacinematograph.EdisonwasquicktofollowtheirleadandcreatedhisVitascopeprojectorinlate1895.Withthepotentialtomakemoneybychargingadmissiontomoviesnowwithinreach,theinnovatorsofthefilmindustrywerereadytoexpandtheirbusinessventures.Thereweretwoindustrymodelsinpracticeduringtheearly1900s.Ahandfulofsuccessfulfirms,suchastheBiographCompany,ownedtheequipmenttomaketheirownfilmsaswellasthevenuesinwhichtodisplaythem.Suchcompanieswererare,however;mostfilmswereshownbyindependentexhibitors.Theseincludedtraditionaltheaterowners,whoaddedshortfilmpresentationstotheirprogramsoflive-actionentertainment,andtravelingcinemaexhibitors,whomovedfromtowntotowntoreachnewaudiences,oftenfollowingcircuitsestablishedbyruralfairs.Theytypicallypurchasedfilmsdirectlyfromtheproductioncompaniesthatmadethem,payingasetpriceperfootoffilmregardlessofitscontent.Becausemoviesofthetimewereneverlongerthanoneortwominutes,itwasfeasibletobuythemoutright.However,thissystemfailedtoattractsignificantaudiencesasthepublicsoontiredofthesmallstockoffilmsexhibitorshadtooffer,andthereelsoffilmthemselvesdeterioratedquicklythroughrepeatedtransportandscreeningintravelingcinemashows.Thingschangedagainwhenproducersbeganincreasingthelengthoftheirfilmsinordertotellmorecomplexstories.Longerfilmsentailedhigherprices,anditbecamedifficultforsmall-scaleexhibitorstopurchasethem.This,inturn,preventedproductionstudiosfromcreatingasmanymoviesastheycould,sincetheyhadnoonetosellthemto.Itwaspreciselythisdilemmathatgaverisetothefilmexchange.Anearlyversionofamotion-picturedistributor,filmexchangeswereresponsibleforbridgingthegapbetweenproductionandexhibition.Theyfinancedproductionstudios,givingthemthefundstheyneededtofilmmoremovies.Then,theypurchasedthesefilmsandrentedthemouttoexhibitorsaroundthecountryforafractionofwhatitwouldhavecosttheexhibitorstopurchasethefilmsthemselves.Thefilm-exchangesystemrevolutionizedtheindustry,greatlybenefitingallpartiesinvolved.Filmrentalsallowedexhibitorstoshowawidevarietyofmoviesandgavethemconstantaccesstonewfilmssotheycouldchangetheirprogramsfrequently.Thisledtotheriseofwhatwenowknowasthemovietheater,avenuededicatedsolelytothepublicexhibitionoffilms.Filmexchangesmademoneybytakingapercentageofticketsales,andtheproductionstudioswerepaidbytheexchanges.Moreover,asaresultoftheincreaseinrevenuethatcameasmoviesgainedpopularity,thestudiosbegantofocusonelevatingthequalityoftheirproducts.Manyhistoriansviewthedevelopmentoffilmexchangesasthesinglemostimportantfactorinthetransformationofthefilmindustryfromanentertainmentnoveltytoamajorbusiness.After1920,independentexchangesgrewscarcerasafewcorporationssucceededincapturingcontroloftheproduction,distribution,andexhibitionoffilms.Yetmanyofthepracticesestablishedbyfilmexchangespriortothe1920sarestillusedtodaybythemostsuccessfulHollywooddistributors.

Reading2"PaleolithicArt"→Theseveralmillenniafollowing30,000B.C.sawapowerfuloutburstofartisticcreativity.Theartworksproducedrangefromsimpleshellnecklacestohumanandanimalformsinivory,clay,andstonetomonumentalpaintings,engravings,andreliefsculpturescoveringthehugewallsurfacesofcaves.Fromthemomentin1879thatcavepaintingswerediscoveredatAltamira,scholarshavewonderedwhythehunter-artistsoftheOldStoneAgedecidedtocoverthewallsofdarkcavernswithanimalimages.Variousanswershavebeengiven,includingthattheyweremeredecoration,butthistheorycannotexplainthenarrowrangeofsubjectsortheinaccessibilityofmanyofthepaintings.Infact,theremotenessanddifficultyofaccessofmanyofthecavepaintingsandthefacttheyappeartohavebeenusedforcenturiesarepreciselywhathaveledmanyscholarstosuggestthattheprehistorichuntersattributedmagicalpropertiestotheimagestheypainted.Accordingtothisargument,byconfininganimalstothesurfacesoftheircavewalls,theartistsbelievedtheywerebringingthebeastsundertheircontrol.Somehaveevenhypothesizedthatritualsordanceswereperformedinfrontoftheimagesandthattheseritesservedtoimprovethehunters'luck.Stillothershavestatedthatthepaintedanimalsmayhaveservedasteachingtoolstoinstructnewhuntersaboutthecharacterofthevariousspeciestheywouldencounteroreventoserveastargetsforspears!Bycontrast,somescholarshavearguedthatthemagicalpurposeofthepaintingswasnottofacilitatethedestructionofbisonandotherspecies.Instead,theybelieveprehistoricpainterscreatedanimalimagestoassurethesurvivaloftheherds.Paleolithicpeoplesdependedonfortheirfoodsupplyandfortheirclothing.Acentralproblemforboththehunting-magicandfoodcreationtheoriesisthattheanimalsthatseemtohavebeendietstaplesofOldStoneAgepeoplesarenotthosemostfrequentlyportrayed.Otherscholarshavesoughttoreconstructanelaboratemythologybasedonthecavepaintings,suggestingthatPaleolithichumansbelievedtheyhadanimalancestors.Stillothershaveequatedcertainspecieswithmenandotherswithwomenandalsofoundsexualsymbolismintheabstractsignsthatsometimesaccompanytheimages.Almostallofthesetheorieshavebeendiscreditedovertime,andarthistoriansmustadmitthatnooneknowstheintentofthesepaintings.Infact,asingleexplanationforallPaleolithicmurals,evenpaintingssimilarinsubject,style,andcomposition(howthemotifsarearrangedonthesurface),isunlikelytoapplyuniversally.Fornow,thepaintingsremainanenigma.→ThatthepaintingsdidhavemeaningtothePaleolithicpeopleswhomadeandobservedthemcannot,however,bedoubted.Infact,signsconsistingofchecks,dots,squares,orotherarrangementsoflinesoftenaccompanythepicturesofanimals.Severalobservershaveseenaprimitivewritingformintheserepresentationsofnonlivingthings,butthesigns,too,mayhavehadsomeothersignificance.Somelookliketrapsandarrowsand,accordingtothehunting-magictheory,mayhavebeendrawntoinsuresuccessincapturingorkillinganimalswiththesedevices.AtPech-MerleinFrance,the"spottedhorses"paintedonthecavewallmaynothavespots.Somescholarshavearguedthatthe"spots,"whichappearbothwithinandwithoutthehorses'outlines,arepaintedrocksthrownattheanimals.→Representationsofhumanhandsalsoarecommon.ThosearoundthePech-Merlehorses,andthemajorityofpaintedhandsatothersites,are"negative,"thatis,theartistplacedonehandagainstthewallandthenpaintedorblewpigmentaroundit.Occasionally,theartistdippedahandinpaintandthenpresseditagainstthewall,leavinga"positive"imprint.Thesehandprints,too,musthavehadapurpose.Somescholarshaveconsideredthem"signatures"ofcultorcommunitymembersor,lesslikely,ofindividualartists.

Types of Money The functions of money as a medium of exchange and a measure of value greatly facilitate the exchange of goods and services and the specialization of production. Without the use of money, trade would be reduced to barter, or the direct exchange of one commodity for another. This was the means of exchange used in primitive societies, and bartering is still practiced in some parts of the world today. In a barter economy, a person having something to trade must find another who wants it and has something acceptable to offer in exchange. In a money economy, the owner of a commodity may sell it for money, which is acceptable in payment for a wide range of other goods or services, thus avoiding the time and effort that would be required to find someone who could make an acceptable trade. Money may thus be regarded as a keystone of modern economic life. The most important types of money are commodity money, credit money, and fiat money. The value of commodity money is about equal to the value of the material contained in it. The principal materials used for this type of money have been gold, silver, and copper. In ancient times, various articles made of these metals, as well as of iron and bronze, were used as money, while among primitive societies commodities such as shells, beads, elephant tusks, furs, skins, and livestock served as mediums of exchange. The gold coins that circulated in the United States before 1933 were examples of commodity money because the value of the gold contained in the coin was about equal to the value of the coin. Credit money is paper backed by promises by the issuer, whether a government or a bank, to pay an equivalent value in the standard monetary metal, such as gold or silver. Paper money that is not redeemable in any other type of money and the value of which is fixed merely by government edict is known as fiat money. This is the type of money found today in the United States in the form of both coins and dollar bills. Credit money becomes fiat money when the issuing government suspends the convertibility of credit money into precious metal. Most fiat money began as credit money, such as the U.S. note known as the greenback which was issued during the American Civil War. Most minor coins in circulation are also a form of fiat money, because the value of the material of which they are made is usually less than their value as money. For example, the amount of nickel in a nickel coin today is less than its value as money. Both the fiat and credit forms of money are generally made acceptable through a government decree that all creditors must take the money in settlement of debts; the money is then referred to as legal tender. If the supply of paper money is not excessive in relation to the needs of trade and industry and people feel confident that this situation will continue, the currency is likely to be generally acceptable and to be relatively stable in value. If, however, such currency is issued in excessively large volume in order to finance government needs, confidence is destroyed and it rapidly loses value. Such depreciation of the currency is often followed by formal devaluation, or reduction of the official value of the currency, by governmental decree. The basic money of a country into which other forms of money may be converted and which determines the value of other kinds of money is called the money of redemption or standard money.A. [■]Modern standards have been either commodity standards, in which either gold or silver has been chiefly used as standard money, or fiat standards, consisting of inconvertible currency paper units.B. [■]Most monetary systems of the world at the present time, including those in China and the United States, are fiat systems. C. [■]They do not allow free convertibility of the currency into a metallic standard, and money is given value by government fiat or edict rather than by its nominal gold or silver content. D. [■]Modern systems are also described as managed currencies, because the value of the currency depends to a considerable extent on government management and policies. Internally, the monetary systems of China and the United States contain many elements of managed currency; although gold coinage is no longer permitted, gold may be owned, traded, or used for industrial purposes.

TransientLunarPhenomenaFormanyyears,skywatchershavereportedseeingmysterioussightsknownasTransientLunarPhenomena(TLP)onthesurfaceofthemoon.Theseareoftwomaintypes:fleetingflashesoflightandspreadingcloudsofmist.Mostprofessionalastronomershavetendedtodismissthesephenomenaasfigmentsoftheobservers'imaginationoras"observationalerrors":eitheropticalillusionsorproblemswiththeobservers'telescopes.OneexplanationputforthbyprofessionalastronomersblamestheflashesonEarthsatellitespassinginfrontofthemoon.Satellitesurfacescanflashlikeacar'swindshieldinsunlight,simulatingalunarflash.ItwasthismechanismthatastronomersR.R.RasteandP.MaleyusedtoexplainalargelunarflashobservedonMarch23,1983,andothersightingsaswell.OneproblemwiththesatellitetheoryisthatTLPwerereportedlongbeforetheadventofartificialsatellites.Theearliestknownaccountcomesfromthetwelfth-centurywriterGervase.OnJune18,1178,inCanterbury,England,Gervasewasobservinganeclipseofthemoon.Hewasstartledbywhatappearedtobe"aflamingtorch,thatspewedoutfire,hotcoals,andsparks".Eighteenth-centuryastronomerSirWilliamHerschel,discovereroftheplanetUranus,alsoreportedseeingbothtypesofTLP.HedescribedoneTLPaslookinglikeapieceofslowlyburningcharcoal.In1830,AndrewGrant,studyingthemoonfromanobservatoryinCapeTown,SouthAfrica,alsoobservedflashinglights.Hetoldnewspaperreportersthathebelievedthelightscamefromthesunflashingoffclearglassdomesthatcoveredcitiesandforestsontheotherwisedeadmoon.Grantclaimedinaninterviewthathehadseenflocksofredandwhitebirds,herdsof"diminutivebison",andstrangebeaversthatwalkedontheirhindlegs.Notonlythat,butheclaimedeventohaveseenpeoplewithbatlikewingswhohadbuilttowersandpyramidsbeneaththedomes.Inmorerecenttimes,arecordnumberofTLPweremonitoredfrom1968to1972,duringtheApollomissionstothemoon.Thisfactishardlysurprisinggiventhatmoretelescopeswereprobablytrainedonthemoonduringthesefouryearsthanhadbeenintheentire270-yearhistoryoftelescopicobservationprecedingthattime.Thoughmanysightingsweredubious,somewerehighlyplausiblebecausetheyweremadebyindependentobserversatdifferentlocations.AnothernotableTLPobservation,andtheonlyoneconfirmedbyphotographicevidence,tookplaceonApril23,1994.WhenoverahundredamateurastronomersreportedseeingadarkredcloudspreadingacrossaportionoftheAristarchuscrater,astronomerBonnieBurattioftheJetPropulsionLaboratorydecidedtoinvestigate.ShegotaccesstophotographsofthemoontakenbytheU.S.lunarmappingsatelliteClementine,andindeed,theseimagesconfirmedthepresenceofareddishcloudobscuringpartofthecrater.EventhosewhobelieveinTLPcannotagreewhythemoonsporadicallyflashesandformsclouds,butmanytheorieshavebeenproposed.Anotherpossibilityisthat,insomeplacesonthemoon,therearechemicalsthatglowwhentheyareexposedtoburstsofradiationfromthesunduringsolarflares.Thereis,infact,someevidencethatTLPareobservedmorefrequentlyduringepisodesofsolaractivity.AfterProjectApolloastronautsbroughtlunarrocksbacktotheearth,scientistsdeterminedthatthereareflammablegasesinsidesomemoonrocks.Perhapstheserockscrackopenandarethenignitedbyastrayspark,causingtheflash.However,whatcausestheserockstosplitopen?Onepossibilityis"thermalcracking".Arockheatsupintheintensesunlight.Suddenly,whenthesunsets,thetemperaturedrops,andthestonecracks.Therocksmightalsobeshatteredby"moonquakes",seismicactivityonthemoon,orbymeteors.ScientistR.Zitobelievestheflashescomenotfromgastrappedinsidetherocksbutfromthecrystalsoftherocksthemselves.Ifsomeonechewsasugarcubeinadarkroom,sparksappeartocomefromtheperson'smouthasthesugarcrystalsarecrushed.Zitobelievesthatthis"sugarcubeeffect"occurswhenmeteorssmashintolunarrocks,crushingthecrystals.Andwhataboutthebillowingclouds?Themostcommonlyheldbelieftodayisthattheyarecausedbypocketsofgastrappedbeneaththelunarsurface.Thecloudsmaybecausedbytherapidescapeofthesegases,whichkicksupcloudsofdust.Thepocketsofgasmaybefreedbymoonquakesorthepocketsmaybepuncturedbymeteors.ThetruecauseofTLP--ifindeedtheydoexist--isstillanunsolvedmystery,however,andwillprobablyremainthatwayatleastuntilhumansreturntothemoon.

→Mammalsandbirdsgenerallymaintainbodytemperaturewithinanarrowrange(36-38℃formostmammalsand39-42℃formostbirds)thatisusuallyconsiderablywarmerthantheenvironment.Becauseheatalwaysflowsfromawarmobjecttocoolersurroundings,birdsandmammalsmustcounteracttheconstantheatloss.Thismaintenanceofwarmbodytemperaturedependsonseveralkeyadaptations.Themostbasicmechanismisthehighmetabolicrateofendothermyitself.Endothermscanproducelargeamountsofmetabolicheatthatreplacetheflowofheattotheenvironment,andtheycanvaryheatproductiontomatchchangingratesofheatloss.Heatproductionisincreasedbysuchmuscleactivityasmovingorshivering.Insomemammals,certainhormonescancausemitochondriatoincreasetheirmetabolicactivityandproduceheatinsteadofATP.Thisnonshiveringthermogenesis(NST)takesplacethroughoutthebody,butsomemammalsalsohaveatissuecalledbrownfatintheneckandbetweentheshouldersthatisspecializedforrapidheatproduction.ThroughshiveringandNST,mammalsandbirdsincoldenvironmentscanincreasetheirmetabolicheatproductionbyasmuchas5to10timesabovetheminimallevelsthatoccurinwarmconditions.→Anothermajorthermoregulatoryadaptationthatevolvedinmammalsandbirdsisinsulation(hair,feathers,andfatlayers),whichreducestheflowofheatandlowerstheenergycostofkeepingwarm.Mostlandmammalsandbirdsreacttocoldbyraisingtheirfurorfeathers,therebytrappingathickerlayerofair.Humansrelymoreonalayeroffatjustbeneaththeskinasinsulation;goosebumpsareavestigeofhair-raisingleftoverfromourfurryancestors.Vasodilationandvasoconstrictionalsoregulateheatexchangeandmaycontributetoregionaltemperaturedifferenceswithintheanimal.Forexample,heatlossfromahumanisreducedwhenarmsandlegscooltoseveraldegreesbelowthetemperatureofthebodycore,wheremostvitalorgansarelocated.→Hairlosesmostofitsinsulatingpowerwhenwet.Marinemammalssuchaswhalesandsealshaveaverythicklayerofinsulationfatcalledblubber,justundertheskin.Marinemammalsswiminwatercolderthantheirbodycoretemperature,andmanyspeciesspendatleastpartoftheyearinnearlyfreezingpolarseas.Thelossofheattowateroccurs50to100timesmorerapidlythanheatlosstoair,andtheskintemperatureofamarinemammalisclosetowatertemperature.Evenso,theblubberinsulationissoeffectivethatmarinemammalsmaintainbodycoretemperaturesofabout36-38℃withmetabolicratesaboutthesameasthoseoflandmammalsofsimilarsize.Theflippersortailofawhaleorseallackinsulatingblubber,butcountercurrentheatexchangersgreatlyreduceheatlossintheseextremities,astheydointhelegsofmanybirds.→Throughmetabolicheatproduction,insulation,andvascularadjustments,birdsandmammalsarecapableofastonishingfeatsofthermoregulation.Forexample,smallbirdscalledchickadees,whichweighonly20grams,canremainactiveandholdbodytemperaturenearlyconstantat40℃inenvironmentaltemperaturesaslowas-40℃—aslongastheyhaveenoughfoodtosupplythelargeamountofenergynecessaryforheatproduction.Manymammalsandbirdsliveinplaceswherethermoregulationrequirescoolingoffaswellaswarming.Forexample,whenamarinemammalmovesintowarmseas,asmanywhalesdowhentheyreproduce,excessmetabolicheatisremovedbyvasodilationofnumerousbloodvesselsintheouterlayeroftheskin.Inhotclimatesorwhenvigorousexerciseaddslargeamountsofmetabolicheattothebody,manyterrestrialmammalsandbirdsmayallowbodytemperaturetorisebyseveraldegrees,whichenhancesheatlossbyincreasingthetemperaturegradientbetweenthebodyandawarmenvironment.→Evaporativecoolingoftenplaysakeyroleindissipatingthebodyheat.Ifenvironmentaltemperatureisabovebodytemperature,animalsgainheatfromtheenvironmentaswellasfrommetabolism,andevaporationistheonlywaytokeepbodytemperaturefromrisingrapidly.Pantingisimportantinbirdsandmanymammals.Somebirdshaveapouchrichlysuppliedwithbloodvesselsinthefloorofthemouth;flutteringthepouchincreasesevaporation.Pigeonscanuseevaporativecoolingtokeepbodytemperaturecloseto40℃inairtemperaturesashighas60℃,aslongastheyhavesufficientwater.Manyterrestrialmammalshavesweatglandscontrolledbythenervoussystem.Othermechanismsthatpromoteevaporativecoolingincludespreadingsalivaonbodysurfaces,anadaptationofsomekangaroosandrodentsforcombatingsevereheatstress.Somebatsusebothsalivaandurinetoenhanceevaporativecooling.GlossaryATP:energythatdrivescertainreactionsincellsmitochondria:amembraneofATP

FilmExchangesinAmerica'sEarlyMovieIndustry1．Motionpictureswereexhibitedtothepublicinthelate1800s,thoughthefirstdevicetoaccomplishthiswouldseemveryunfamiliartotoday'smovie-goingaudiences.ThomasEdison's1893Kinetoscopewaslittlemorethanawoodenboxwithasmallglasswindow.Intendedonlyforindividualviewing,ithousedarolloffilm,amechanicaldevicetocirculatethefilm,andasmalllighttoilluminateit.Apersonwouldpeerthroughthewindowandwatchashortmovingsequence,usuallyjustadepictionofaneverydayeventortheperformanceofanacrobatordancer.Needlesstosay,themedium'sabilitytoserveonlyonecustomeratatimeseverelylimiteditsprofitability.2．Everythingchangedtwoyearslaterwiththeadventofprojection,bywhichamuchlargerfilmimagecouldbeshowntomultipleviewerssimultaneously.TheLumièrebrothersofFrancewerethefirsttointroducethisnewtechnologywithaprojectionmachinecalledacinematograph.EdisonwasquicktofollowtheirleadandcreatedhisVitascopeprojectorinlate1895.Withthepotentialtomakemoneybychargingadmissiontomoviesnowwithinreach,theinnovatorsofthefilmindustrywerereadytoexpandtheirbusinessventures.3．Thereweretwoindustrymodelsinpracticeduringtheearly1900s.Ahandfulofsuccessfulfirms,suchastheBiographCompany,ownedtheequipmenttomaketheirownfilmsaswellasthevenuesinwhichtodisplaythem.Suchcompanieswererare,however;mostfilmswereshownbyindependentexhibitors.Theseincludedtraditionaltheaterowners,whoaddedshortfilmpresentationstotheirprogramsoflive-actionentertainment,andtravelingcinemaexhibitors,whomovedfromtowntotowntoreachnewaudiences,oftenfollowingcircuitsestablishedbyruralfairs.Theytypicallypurchasedfilmsdirectlyfromtheproductioncompaniesthatmadethem,payingasetpriceperfootoffilmregardlessofitscontent.Becausemoviesofthetimewereneverlongerthanoneortwominutes,itwasfeasibletobuythemoutright.However,thissystemfailedtoattractsignificantaudiencesasthepublicsoontiredofthesmallstockoffilmsexhibitorshadtooffer,andthereelsoffilmthemselvesdeterioratedquicklythroughrepeatedtransportandscreeningintravelingcinemashows.4．Thingschangedagainwhenproducersbeganincreasingthelengthoftheirfilmsinordertotellmorecomplexstories.Longerfilmsentailedhigherprices,anditbecamedifficultforsmall-scaleexhibitorstopurchasethem.This,inturn,preventedproductionstudiosfromcreatingasmanymoviesastheycould,sincetheyhadnoonetosellthemto.Itwaspreciselythisdilemmathatgaverisetothefilmexchange.Anearlyversionofamotion-picturedistributor,filmexchangeswereresponsibleforbridgingthegapbetweenproductionandexhibition.Theyfinancedproductionstudios,givingthemthefundstheyneededtofilmmoremovies.Then,theypurchasedthesefilmsandrentedthemouttoexhibitorsaroundthecountryforafractionofwhatitwouldhavecosttheexhibitorstopurchasethefilmsthemselves.5．Thefilm-exchangesystemrevolutionizedtheindustry,greatlybenefitingallpartiesinvolved.Filmrentalsallowedexhibitorstoshowawidevarietyofmoviesandgavethemconstantaccesstonewfilmssotheycouldchangetheirprogramsfrequently.Thisledtotheriseofwhatwenowknowasthemovietheater,avenuededicatedsolelytothepublicexhibitionoffilms.Filmexchangesmademoneybytakingapercentageofticketsales,andtheproductionstudioswerepaidbytheexchanges,Moreover,asaresultoftheincreaseinrevenuethatcameasmoviesgainedpopularity,thestudiosbegantofocusonelevatingthequalityoftheirproducts.6．Manyhistoriansviewthedevelopmentoffilmexchangesasthesinglemostimportantfactorinthetransformationofthefilmindustryfromanentertainmentnoveltytoamajorbusiness.After1920,independentexchangesgrewscarcerasafewcorporationssucceededincapturingcontroloftheproduction,distribution,andexhibitionoffilms.Yetmanyofthepracticesestablishedbyfilmexchangespriortothe1920sarestillusedtodaybythemostsuccessfulHollywooddistributors.

THE MOON 1 {{U}}The moon is the closest natural body and the single natural satellite of the earth{{/U}}. The orbit of the moon around the earth is not circular but elliptical. Thus, the distance of the moon from the earth varies from a maximum distance of 406,685 kilometers to a minimum of 356,410 kilometers. In one day, the moon moves about 12 degrees along its orbit. The moon completes one revolution of the earth in 27.3 days, a period known as a sidereal month. 2 The moon rotates slowly on its axis, making one complete rotation in a period of time exactly equal to its orbit around the earth. Thus, the moon keeps the same hemisphere or face turned toward the earth at all times. We do not, however, always see only half of the moon's surface from the earth. The {{U}}eccentricity{{/U}} of the moon's orbit allows us to see additional lunar surface through irregular movements called librations, which expose an extra 18 percent of the moon's surface at one time or another. 3 In 1969, the first humans landed on the moon's surface in the Sea of Tranquility. Subsequent lunar landings were on the Ocean of Storms and the Sea of Serenity. Despite these watery names, the astronauts had to cope with an environment {{U}}devoid of{{/U}} water. The dark areas on the moon's surface are called seas and oceans because early observers assumed the moon was much like the earth. We now know that the seas are dark because they are volcanic basalt flows, mostly of iron silicate. The brighter parts, the mountains, consist of igneous deposits of aluminum and calcium silicates. 4 Like the earth, the moon has no light of its own; its daylight side reflects the light of the sun. The moon goes through phases, apparent changes in its shape, because it orbits the earth in nearly the same plane as the earth orbits the sun. The eight phases of the moon arise from its changing position in relation to the earth. At the new moon, the start of the first phase, the dark side of the moon is turned toward the earth, so the moon cannot be seen. A few nights later, a thin crescent hangs in the evening twilight. At this time, the dark side of the moon is faintly visible because it is illuminated by earthshine, the light of the sun reflected from the earth to the moon, then back again. 5 The second phase is a waxing crescent moon, followed by the third phase, when the moon forms a right angle with the earth-sun line, and a half moon appears at sunset. During the fourth phase, the moon is more than half but less than fully illuminated, known as a waxing gibbous moon. The waxing gibbous moon is followed by a full moon (fifth phase), which occurs when the sun, earth, and moon are in opposition, or roughly aligned. At full moon, the rising disk of the moon appears to balance the setting sun in the evening sky. When the moon is just past full, a lunar twilight--seen as a glow in the eastern sky--will precede moonrise. 6 After the full moon, the moon begins to {{U}}wane{{/U}}, through a waning gibbous moon (sixth phase), a waning half moon (seventh phase), and a waning crescent moon (eighth phase). Toward the end of the eighth phase, a thin crescent appears at morning twilight, again accompanied by earthshine. Finally, the cycle ends and another begins with a dark moon: another new moon. The lunar cycle takes 29.5 days to complete--a period known as a synodic month or the moon's synodic period. 7 At its full phase, the moon's intensity is about one millionth that of the sun, and it is possible to read a newspaper by the light of the moon. The full moon nearest the autumnal equinox in September is called the Harvest Moon. The Harvest Moon {{U}}ushers in{{/U}} a period of several successive days when the moon rises in the northeast soon after sunset. This phenomenon gives farmers in temperate latitudes extra hours of light in which to harvest their crops before frost and winter come. The full moon following the Harvest Moon is called the Hunter's Moon and is accompanied by a similar but less marked phenomenon of early moonrise.

Directions: Read the passage. Then answer the questions. Give yourself 20 minutes to complete this practice set. MINERALS AND PLANTS Research has shown that certain minerals are required by plants for normal growth and development. The soil is the source of these minerals, which are absorbed by the plant with the water from the soil. Even nitrogen, which is a gas in its elemental state, is normally absorbed from the soil as nitrate ions. Some soils are notoriously deficient in micro nutrients and are therefore unable to support most plant life. So-called serpentine soils, for example, are deficient in calcium, and only plants able to tolerate low levels of this mineral can survive. In modern agriculture, mineral depletion of soils is a major concern, since harvesting crops interrupts the recycling of nutrients back to the soil. Mineral deficiencies can often be detected by specific symptoms such as chlorosis (loss of chlorophyll resulting in yellow or white leaf tissue), necrosis (isolated dead patches), anthocyanin formation (development of deep red pigmentation of leaves or stem), stunted growth, and development of woody tissue in an herbaceous plant. Soils are most commonly deficient in nitrogen and phosphorus. Nitrogen-deficient plants exhibit many of the symptoms just described. Leaves develop chlorosis; stems are short and slender; and anthocyanin discoloration occurs on stems, petioles, and lower leaf surfaces. Phosphorus-deficient plants are often stunted, with leaves turning a characteristic dark green, often with the accumulation of anthocyanin. Typically, older leaves are affected first as the phosphorus is mobilized to young growing tissue. Iron deficiency is characterized by chlorosis between veins in young leaves. Much of the research on nutrient deficiencies is based on growing plants hydroponically, that is, in soil-less liquid nutrient solutions. This technique allows researchers to create solutions that selectively omit certain nutrients and then observe the resulting effects on the plants. Hydroponics has applications beyond basic research, since it facilitates the growing of greenhouse vegetables during winter. Aeroponics, a technique in which plants are suspended and the roots misted with a nutrient solution, is another method for growing plants without soil. While mineral deficiencies can limit the growth of plants, an overabundance of certain minerals can be toxic and can also limit growth. Saline soils, which have high concentrations of sodium chloride and other salts, limit plant growth, and research continues to focus on developing salt-tolerant varieties of agricultural crops. Research has focused on the toxic effects of heavy metals such as lead, cadmium, mercury, and aluminum; however, even copper and zinc, which are essential elements, can become toxic in high concentrations. Although most plants cannot survive in these soils, certain plants have the ability to tolerate high levels of these minerals. Scientists have known for some time that certain plants, called hyperaccumulators, can concentrate minerals at levels a hundredfold or greater than normal. A survey of known hyperaccumulators identified that 75 percent of them amassed nickel; cobalt, copper, zinc, manganese, lead, and cadmium are other minerals of choice. Hyperaccumulators run the entire range of the plant world. They may be herbs, shrubs, or trees. Many members of the mustard family, spurge family, legume family, and grass family are top hyperaccumulators. Many are found in tropical and subtropical areas of the world, where accumulation of high concentrations of metals may afford some protection against plant-eating insects and microbial pathogens. Only recently have investigators considered using these plants to clean up soil and waste sites that have been contaminated by toxic levels of heavy metals—an environmentally friendly approach known as phytoremediation. This scenario begins with the planting of hyperaccumulating species in the target area, such as an abandoned mine or an irrigation pond contaminated by runoff. Toxic minerals would first be absorbed by roots but later relocated to the stem and leaves. A harvest of the shoots would remove the toxic compounds off site to be burned or composted to recover the metal for industrial uses. After several years of cultivation and harvest, the site would be restored at a cost much lower than the price of excavation and reburial, the standard practice for remediation of contaminated soils. For example, in field trials, the plant alpine pennycress removed zinc and cadmium from soils near a zinc smelter, and Indian mustard, native to Pakistan and India, has been effective in reducing levels of selenium salts by 50 percent in contaminated soils.

Listentopartofaconversationbetweenanadvisorandastudent.Nowgetreadytoanswerthequestions.Youmayuseyournotestohelpyouanswer.

Directions : Read the passage

Directions: Read the passage. Then answer the questions. Give yourself 20 minutes to complete this practice set. POPULATION AND CLIMATE The human population on Earth has grown to the point that it is having an effect on Earth's atmosphere and ecosystems. Burning of fossil fuels, deforestation, urbanization, cultivation of rice and cattle, and the manufacture of chlorofluorocarbons (CFCs) for propellants and refrigerants are increasing the concentration of carbon dioxide, methane, nitrogen oxides, sulphur oxides, dust, and CFCs in the atmosphere. About 70 percent of the Sun's energy passes through the atmosphere and strikes Earth's surface. This radiation heats the surface of the land and ocean, and these surfaces then reradiate infrared radiation back into space. This allows Earth to avoid heating up too much. However, not all of the infrared radiation makes it into space; some is absorbed by gases in the atmosphere and is reradiated back to Earth's surface. A greenhouse gas is one that absorbs infrared radiation and then reradiates some of this radiation back to Earth. Carbon dioxide, CFCs, methane, and nitrogen oxides are greenhouse gases. The natural greenhouse effect of our atmosphere is well established. In fact, without greenhouse gases in the atmosphere, scientists calculate that Earth would be about 33℃ cooler than it currently is. The current concentration of carbon dioxide in the atmosphere is about 360 parts per million. Human activities are having a major influence on atmospheric carbon dioxide concentrations, which are rising so fast that current predictions are that atmospheric concentrations of carbon dioxide will double in the next 50 to 100 years. The Intergovernmental Panel on Climate Change (IPCC) report in 1992, which represents a consensus of most atmospheric scientists, predicts that a doubling of carbon dioxide concentration would raise global temperatures anywhere between 1.4℃ and 4.5℃. The IPCC report issued in 2001 raised the temperature prediction almost twofold. The suggested rise in temperature is greater than the changes that occurred in the past between ice ages. The increase in temperatures would not be uniform, with the smallest changes at the equator and changes two or three times as great at the poles. The local effects of these global changes are difficult to predict, but it is generally agreed that they may include alterations in ocean currents, increased winter flooding in some areas of the Northern Hemisphere, a higher incidence of summer drought in some areas, and rising sea levels, which may flood low-lying countries. Scientists are actively investigating the feedback mechanism within the physical, chemical, and biological components of Earth's climate system in order to make accurate predictions of the effects the rise in greenhouse gases will have on future global climates. Global circulation models are important tools in this process. These models incorporate current knowledge on atmospheric circulation patterns, ocean currents, the effect of landmasses, and the like to predict climate under changed conditions. There are several models, and all show agreement on a global scale. For example, all models show substantial changes in climate when carbon dioxide concentration is doubled. However, there are significant differences in the regional climates predicted by different models. Most models project greater temperature increases in mid-latitude regions and in mid-continental regions relative to the global average. Additionally, changes in precipitation patterns are predicted, with decreases in mid-latitude regions and increased rainfall in some tropical areas. Finally, most models predict that there will be increased occurrences of extreme events, such as extended periods without rain (drought), extreme heat waves, greater seasonal variation in temperatures, and increases in the frequency and magnitude of severe storms. Plants and animals have strong responses to virtually every aspect of these projected global changes. The challenge of predicting organismal responses to global climate change is difficult. Partly, this is due to the fact that there are more studies of short-term, individual organism responses than there are of long-term, systemwide studies. It is extremely difficult, both monetarily and physically, for scientists to conduct field studies at spatial and temporal scales that are large enough to include all the components of real-world systems, especially ecosystems with large, freely ranging organisms. One way paleobiologists try to get around this limitation is to attempt to reconstruct past climates by examining fossil life. The relative roles that abiotic and biotic factors play in the distribution of organisms is especially important now, when the world is confronted with the consequences of a growing human population. Changes in climate, land use, and habitat destruction are currently causing dramatic decreases in biodiversity throughout the world. An understanding of climate-organism relationships is essential to efforts to preserve and manage Earth's biodiversity.