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CELL PROCESSES AND ENERGY. CHAPTER II SECTION I - PHOTOSYNTHESYS. PHOTOSYNTESIS.
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CELL PROCESSES AND ENERGY CHAPTER II SECTION I - PHOTOSYNTHESYS
PHOTOSYNTESIS • Theprocessbywhich a cell captures energy in sunlight and uses ittomakefoodiscalledphotosyntesis. Nearlyall living thingsobtainenergydirectlyorindirectlyfromtheenergysunlihtcapturedduringphotosyntesis.
PHOTOSYNTESIS • Grassobtainsenergydirectlyfromsunlight, beacuseitmakesitsownfoodduringphotosyntesis, whenan animal eatsthegrass, itgetsenergythat has beenstored in thegrass, and thepredetorobteinstheenergystoredbythe animal whoeatsthegrass.
PHOTOSYNTESIS • Plants manufacture theirownfoodthroughtheprocess of photosyntesis, anorganismthatmakesitsownfoodiscalled AN AUTOTROPH. Anorganismthatcannotmakeitsownfood, includinganimals and humans, iscalled HETEROTROPH.
THE TWO STAGES OF PHOTOSYNTESIS • Duringphotosyntesisplants and someotherorganisms use energyfromthesuntoconvertcarbondioxide and waterintooxygen and sugar.
THE TWO STAGES OF PHOTOSYNTESIS • STAGE 1. CAPTURING THE SUN’S ENERGY: thefirststage of thephotosyntesisinvolvescapturingtheenergy in sunlight. In plantsthisenergy-capturingprocessoccursmostly in theleaves, thegreen color comes fromthe PIGMENTS, coloredthechemicalcompoundsthatabsorb light. • Themainphotosynteticpigment in chloroplastsis CHLOROPHYLL, thatfunctions in a manner similar tothat of the solar cells, that capture theenergy in light and uses ittopowerthesecondstage of photosyntesis.
THE TWO STAGES OF PHOTOSYNTESIS • STAGE 2. USING ENERGY TO MAKE FOOD. In thenextstage of photosyntesis, thecell uses thecapturedenergyto produce sugars. Thecellneedstworawmaterialsforthisstage: water (H2o) and Carbondioxide (Co2). In plantsthetherootsabsorbwaterfromthesoil, thewaterthenmoves up throughtheplant’ssteamtotheleaves.
THE TWO STAGES OF PHOTOSYNTESIS • Carbondioxideenterstheplantthroughsmallopeningsontheundersides of theleavescalled STOMATA, once in theleaves, thewater and carbondioxidemoveintothechloroplasts. • Insidethechloroplaststhewater and carbondioxideundergo a complex series of chemicalreactions as products.
THE TWO STAGES OF PHOTOSYNTESIS • Oneproductis a sugarthat has sixcarbonatoms, cells can use theenergy in thesugartocarryoutimportantcellsfunctions. • Theotherproduct of photosyntesisisoxygen, alltheoxygen in Earth’sathmospherewasproducedby living thingsthroughtheprocess of photosyntesis.