School Work


of 23
All materials on our website are shared by users. If you have any questions about copyright issues, please report us to resolve them. We are always happy to assist you.
Related Documents
  Photosynthesis ã The Dark Reactions of Photosynthesis, Assimilation of Carbon Dioxide And The Calvin Cycle  ã C 3 , C 4  and CAM. Re!lation of The Activity of Photosynthesis  ã The iht Reactions of Photosynthesis  ã The Photosynthetic Membrane  ã iterat!re The observation that a #illo# that has been c!ltivated in a container for five years #ith eno!h #aterin ained more than half a centner #eiht altho!h only t#o o!nces of the container$s soil #ere lost oes back to %.&. van '( M)*T +- / 0441. The &ritish nat!ral scientist 2. 'A (2 +0 / 01 !nderstood that air and liht are necessary for the n!trition of reen lants. &!t it #as not before the comosition of air o!t of different ases became kno#n that their sinificance for lant n!trition #as st!dies. n  observed %. PR(2T (5 +33 / 6741, one of the discoverers of oxyen, that reen  lants ive off oxyen and th!s imrove the air. The riest %. 2(*(&(R +48 / 6791 from :eneva discovered that the reeneration of the air is based on the !se of $fixed air$ +carbon dioxide1. These observations #ere confirmed and broadened by st!dies of the D!tch doctor  %. *:(*');2< +37 / 991 #ho reconi=ed both the meanin of liht and the fact that the #hole carbon contained in  lants is of atmosheric oriin. 'e, too, conceived that lants take ! small amo!nts of oxyen at niht or in the shado# and ive off carbon dioxide. n 674 discovered Th. des 2A;22;R( +0 / 64-1 from :eneva that the lants$ increase in #eiht cannot solely  be ca!sed by the !take of carbon and minerals, b!t is based on the bindin of the #ater comonents, too. n 694 constr!cted T. >. (*:( MA** +643 / 9791 a adet o!t of a modified microscoe condenser that allo#ed him to exose arts of hotosynthetically active cells +of the reen ala Spirogyra 1 to a thin ray of liht. 'is aim #as to discover #hich comonents of the cell f!nctioned as liht recetors. To meas!re the oxyen rod!ction, he disersed the thread/like Spirogyra  in a bacteria/containin s!sension. >henever  arts of the chlorolast #ere ill!minated, did the bacteria concentrate in this area +#here oxyen #as available1. The ill!mination of other arts of the cell res!lted in no s!ch areations.  n an earlier st!dy did he slit #hite liht into its sectral comonents !sin a rism. 'e then ill!minated a reen ala, Chladophora , #ith this sectr!m. n contrast to Spirogyra  are the Chladophora  cells comletely and evenly filled by the chlorolast. 'e observed that the bacteria acc!m!lated mainly in the bl!e and red liht. A first action sectr!m of  hotosynthesis #as th!s yielded. t resembles ro!hly the absortion sectra of chlorohyll a and b. %. v. 2AC'2 +638 / 691 co!ld finally rove that chlorohyll is involved in  hotosynthesis. n addition did he sho# that starch is rod!ced in chlorolasts as a res!lt of the hotosynthetic activities. These res!lts are in accord #ith the first la# of  thermodynamics, #hose discoverer %. R. MA5(R ost!lated already in 648 that lants take ! enery in the form of liht and that they transform it into another, a chemical state of enery. &ased on this ass!mtion #as the reaction e?!ation 0 carbon dioxide @ 0 #ater  (chlorophyll)   l!cose @ 0 oxyen form!lated. %.v. (&: ass!med that the oxyen stems from the breakdo#n of the carbon dioxide. This idea #as !ncritically acceted by the lant hysioloists of the late 9 th  and the early87 th  cent!ry +2AC'2, PB(BB(R, %)2T and others1 altho!h M. %. 2C' (D(* had as soon as 648 reali=ed that .l!cose is rod!ced as a res!lt of hotosynthesis +and he #as closer to reality than 2AC'2 #as later1 and that is very likely that it is #ater that is broken do#n. 'e #rote t is #ell/kno#n that C) 8  is amon the most stabile como!nds and that no chemical #ay of breakin it do#n is kno#n #hile ' 8 ) is very easily broken do#n.... and it does therefore seem likely that the 84 ' 8  of the 84 ' 8 ) are combined #ith the 8 C) 8 . +from :r!nd=Ee der #issenschaftlichen &otanik1. 2C' (D(*$s e?!ations contain all reaction como!nds in do!ble n!mbers. 'e ives C 8 ' 84 ) 8  as the form!la for l!cose. t #as soon reali=ed that the reaction e?!ation above is a simlification and that  hotosynthesis consists of a n!mber of artial rocesses. B. B. & ACFMA* and :. . C. MAT':( +97-, ;niversity of Cambride, :reat &ritain1 #ere amon the first to st!dy this toic systematically. They c!ltivated lants !nder different b!t controlled carbon dioxide concentrations, different liht intensities and different temerat!res and they noted the effects of these arameters on the rate of  hotosynthesis. T#o decisive asects #ere revealed. ;nder stron liht and limited amo!nts of carbon dioxide is the rate of hotosynthesis deendent on the temerat!re. This sho#s that the carbon dioxide fixation is based on normal, temerat!re/deendent  biochemical reactions. ;nder carbon dioxide excess and too little liht #as no temerat!re/deendence fo!nd. This hints at the fact that the liht/ind!ced reactions are indeendent of the temerat!re. This statement alies to all hotochemical reactions. n 98- !t ). >AR&;R: +Faiser/>ilhelm/nstit!t Glater Max/Planck/nstit!tH fEr <ellhysioloie at &erlin/Dahlem1 the res!lts of & ACFMA* do#n to the existence of t#o classes of hotosynthetic reactions the liht and the dark reactions. D!rin the thirties analy=ed C. &. van *( +2tanford ;niversity1 the hotosynthesis of an!mber of !rle bacteria. n addition to carbon dioxide do these bacteria need hydroen s!lhide for hotosynthesis. van *( #as able to determine  0 C) 8  @ 8 ' 8 2  (light)   C 0 ' l8 ) 0  @ 8 2 @ 0 ' 8 ) as the reaction$s e?!ation. &ased on it did he extraolate a eneral e?!ation of  hotosynthesis C) 8  @ 8 ' 8 I  (light)   +C' 8 )1 @ ' 8 ) @ 8 I Accordin to this e?!ation is hotosynthesis a redox reaction #ith ' 8 I as the electron donator +the oxydi=able s!bstance1. n the case of reen lants is it ' 8 ) and this means that not the carbon dioxide b!t the #ater is broken do#n. A first exerimental rove that the oxyen develoed d!rin the hotosynthesis of reen  lants stems indeed from #ater #as delivered by the &ritish hysioloist R. ' . 'e detected that isolated chlorolasts ive off oxyen in the resence of !nnat!ral red!cin aents like iron oxalate, ferricyanide or ben=o?!inone after exos!re to liht. The reaction #ent do#n in literat!re as the ' /reaction 8 ' 8 ) @ 8 A  (light, chloroplasts)   8 A' 8  @ ) 8  #here A is the electron accetor. f A J Be  , then is 8 ' 8 ) @ 4 Be    (light, chloroplasts)   4 Be   @ ) 8  @ 4 ' @  The rocess is linked to a hotolytic breakdo#n of #ater that recede the red!ctionn of Be  . 4 ' 8 )   (light, chloroplasts)   4 ' @  @ 4 )' /  This sho#s that oxyen can also be set free in the absence of carbon dioxide,the oxyen rod!ced stems from the breakdo#n of #ater,isolated chlorolasts are able to erform at least artial rocesses of hotosynthesis.The statement that the oxyen rod!ced d!rin hotosynthesis stems only from the  breakdo#n of #ater #as confirmed by 2. M. R;&(*, M. RA*DA , M. FAM(* and %. . '5D( in 94 after the isotoe techni?!e had fo!nd its #ay to biochemistry. They co!ld sho#n that a s!sension of Chlorella  ro#n in ' 86 ), ives off 6) 8 , after liht exos!re. 2hortly after#ards confirmed 2. M. R;&(* and his collaborators the ost!lateof ). >AR&;R: that the fixation of carbon dioxide is enery cons!min b!t indeendent of liht. n addition co!ld (. RACF(R +Cornell ;niversity, thaca, *. 5.1  rove that liht can be relaced by the addition of enery/rich como!nds.
We Need Your Support
Thank you for visiting our website and your interest in our free products and services. We are nonprofit website to share and download documents. To the running of this website, we need your help to support us.

Thanks to everyone for your continued support.

No, Thanks