chapter 6 – digestion and nutrition：6章–消化和营养

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1、Chapter6–DigestionandNutritionSection6.2–ImportanceofDigestion(pages208-210)1.Definethetermnutrients.2.Autotrophsneedorganicsubstances;however,theydonoteatthem.Explainhowanapplytreeobtainsitsneededorganicsubstances.3.Whatisdigestionandwhatfourphasesdoesitinclude?4.Whattwofactorsinfluencetheeffect

2、ivenessofanenzyme?5.Whatisthecomplicationwithconsumingchunksoffood?6.Howdoesthepresenceofanalimentarycanalaltertheorganizationofthedigestiveorganswithinthebody?7.Howdoprotozoaabsorb,digestandeliminatetheirfood?Includeadiagramtoillustrateyouranswer.8.Howdoesthehydraobtainnutrients?9.Whatisagastrov

3、ascularcavity?10.Whatismeantbyone-waytrafficindigestion?11.Whatismeantbytwo-waytrafficindigestion?12.Theearthwormisanexampleofanorganismthatusesone-waytrafficindigestion.Explainthedigestiveprocessintheearthworm,includingchemicaldigestionandabsorption.Section6.2–Answers1.Nutrientscanbedefinesascom

4、plexorganicmoleculesandsimplersubstancesthatareneededbylivingorganismstocarryoutsuchlifeprocessesasrespiration,proteinsynthesis,andreproduction.2.Autotrophsbuildthecomplexorganicsubstancestheyrequirebyusingwater,carbondioxide,mineralsabsorbedfromthesoil,andenergyfromthesun.Anappletreewillabsorbwa

5、terandmineralsfromthesoil.Thesemoleculesaresmallenoughtopassdirectlyintothecellsoftheappletree’srootsandfromtheroots,thewaterandmineralsaretransportedtotheleaves.Thereareopeningsintheleavesthatallowcarbondioxidetoenterandphotosynthesistooccur.Thisprocessconvertsthewaterandcarbondioxideintosimples

6、ugarsthatcanbeusedasanenergysourcefortheplant’scells.Someofthesimplesugarsareusedtobuildcomplexmoleculesneededforgrowthandotherlifefunctionssuchasstarch,cellulose,lipidsandaminoacids.3.Digestionisaverycomplexchemicalprocess,whichinvolvesmanyenzymesthatcarryoutaseriesofhydrolysisreactions.Theserea

7、ctionsusewatertoconvertcomplexorganicmoleculesintosimpleronesthatcaneasilydiffuseacrossacellmembrane.Thefourcomponentsofdigestioninclude;ingestion–takinginofnutrients,digestion–thebreakdownofcomplexorganicmoleculesinto