Free Biology NEET Video Lectures for Photosynthesis In Higher Plants

00:00:51 Hello friends, myself BP SA from Kendra Vidya Quesapuram. Today I elaborate the chapter photosynthesis in class 11th. The photosynthesis star is made by two things that means photon which means light and synthesis putting together the somethings. Photosynthesis add the directly means synthesis of organic compound with the help of photon that is light. Generally the green plant make their own food with the help of sunlight and it convert into the chemical energy that is ATP which are being utilized by the consumers as well

00:01:55 as other living organisms. There are many definitions regarding the photosynthesis. The some are important definitions are photosynthesis is a biochemical process by which green plant use radiant energy and convert it into the chemical energy in the form of organic compound. The great scientist Robinovich defined the photosynthesis. It is a synthesized photochemical oxidation and reduction. That means here oxidation and reduction both takes place. That is the redux reaction mechanism between water and

00:02:40 carbon dioxide taking place at biological temperature. Photosynthesis is the only process on the earth by which the radial energy trapped by autoropic organism and converted into food for all the organisms. About 170 millions ton of dry matter in term of carbon is produced by this method out of which 90% form in the ocean. Only 0.2% of light energy incident on earth is utilized by photosynthetic organism. Now what are the importance of photosynthesis? As we already tell it is the only process by which the autoropic

00:03:34 organism make their own food and all the other organisms like uh consumers decomposers which depend directly or indirectly on the producers. So it is primary source of food. It is the only process that release oxygen and you know the oxygen plays vital role in our life. This oxygen help in the breakdown of the food material that we are eating and converted into the ATP which is utilized for various metabolic process like respiration like circulatory system like nervous system. All the this metabolic

00:04:21 process require energy and this energy directly or indirectly oxidized by the oxygen and converted into ATP. About 70 million ton of carbon is fixed annually by the photosynthesis. This is the simplest and to explain the photosynthesis here is the green plant. This is the sunflower is there. Here is the green leaf which is the site of photosynthesis and the radiant energy received by the green leaves with the help of various types of pigments are present here that is chlorophyll A, chlorophyll B, kerotin,

00:05:09 zanthopil and this radiant energy converted into chemical energy and it release oxygen as a byproduct and the carbon Carbon dioxide during the respiration organism release carbon dioxide which is received by plant through the stomata and it converted into carbohydrate and oxygen. This one is the process here is the ingredient and product. The ingredient that means the raw material of photosynthesis that is carbon dioxide, water and certain amount of nutrients that converted into carbohydrate and oxygen. Here we can say

00:05:54 that this hydrogen water and carbon dioxide it convert into carbohydrate and this is the byproduct. This byproduct is utilized by the human being as well as other organisms. Now the historical perspective of the photosynthesis large number of scientist biologist their contribution regarding the photosynthesis. First of all Aristotal and theoprastus thought that plant absorb inorganic and organic material directly from the soil. Plant make food as we have already discussed and for the food preparing the food it required

00:06:45 inorganic and organic substance according to the Aristotal and theoplasters. This material came from the soil. According to the Van Halmont, Van Halmmont in 1648, according to him, all the vegetations, all the living organisms are nothing but water. According to the Von Helmont, he grew a willow pig of about five pound. He watered with the rainwater five years continuously and found that this five pond willow twig converted into 164 pond and three on the consumption of two of the soil and rest amount of

00:07:40 water. So finally he concluded that von Helmon concluded that all vegetation is nothing there is only water because this five pond willow twix converted into 164 pond tweaks only the use of rain water. So all the vegetations are nothing but water. According to the Joseph Priestly in 1722, he proved that green plants purify the air. As we have already discussed during the photosynthesis, the plant release oxygen and this oxygen purify the airs. He gave the famous experiment that is mint mouse and candle

00:08:32 experiment. In this experiment the Joseph Pristle use a bell jar like this and use a candle inside the bell jar. Firstly there is the presence of oxygen. He burnt the candle. Candle blew up. And he take a mouse here. And he found that mice survived. After some times he found that the candle not burnt and mice died. Due to this experiment he concluded that during the burning of candle it released carbon dioxide. This carbon dioxide received by the mice and mice being dead due to the absence of oxygen the

00:09:49 candle not able to burn. In this experiment he added some mint plant certain mint plant and here candle burnt and find that my survived. He concluded that mint plant this carbon dioxide released by the candle received by the mint plant. This is the mint plant received by the mint plant and photosynthesis takes place and it release oxygen. This oxygen help in the burning of candle as well as mice survived. So finally he concluded that green plant that is a mean plant release oxygen purify the poisonous

00:11:07 gases by the mice or the candle burning candle and mice as well as mint plant is survived. So this is a famous experiment known as mint mice and candle experiment given by Joseph Pristlick. According to John Indian horse plant could release oxygen. It is the same process according to the Julia sack starch granules are synthesized in the chloroplast. I will tell later. The leaf is the site of photosynthesis. No doubt inside the leaf there is presence of chloroplast. After the photosynthesis it was found that this chloroplast this is

00:12:05 the outer membrane. This is the inner membrane or this one space is called periplastal space or inside this there is presence of granom and this granom is made by taloquetss and Here is the granules stroma where the one part of photosynthesis that is dark reaction takes place. This one is taloquite. The group of taloquite form granom where the light reaction takes place. According to the Julia Sachs starch he found that after the photosynthesis starch was present and finally he concluded that during the photosynthesis starch is

00:13:25 formed. According to the von mayor 1845 reported that green plant converted solar energy into the chemical energy in the form of carbohydrate like the starch. Immersion and Arnold he perfor they perforing light excerment to show the existence of light and dark reaction. Here we have already told that in chloroplast theoquide as well as estroma are present. In theoquide light reaction takes place and in stroma dark reaction takes place. This dark reaction takes place in absence of light. So when the immersion and Arnold

00:14:20 performed the flashing of light, flashing of light means the light given or light on and off. During the off mechanism, dark reaction takes place. During the on mechanism, light reaction takes place. So they performed that the there are two type of reaction takes place during the photosynthesis that is the light reaction and dark reaction. Now the other scientist that is called blackmans we discover also finally proved that there the presence of light and dark reaction. Now will ster and stall physical and chemical properties of

00:15:03 chlorophyll inside the chloroplast large number of chlorophylls are present. This chlorophyll which absorb particular wavelength of light. Next scientist that is the warbber he used unisellular algae that is the chlorella for the suitable material for photosynthesis. Kola is also extracted which I will deal later on how the kerala plant extracted and from the kera planter chloroplast is extracted. The most famous scientist van nil proved that oxygen is evolved during the photosynthesis by photoolysis of

00:15:51 water. Vonil uses the photosynthetic bacteria. Vanil postulate that green plant in green plant water is utilized in place of H2S and O2 evolved in place of sulfur. He gave the famous reaction during the normal process of photosynthesis. What happened? The carbon dioxide combined with water and it converted into carbohydrate 06 and this oxygen acts as a byproduct. Bondil use instead of water he used hydrogen sulfide and found that carbohydrate is formed in a state of oxygen. sulfur is released. Finally he concluded that

00:17:18 during the photosynthesis oxygen is released. This oxygen came from water because in another reaction this sulfur came from the H2S hydrogen sulfide. Here there is no water. So the oxygen came from the water instead of carbon dioxide. Here we can say that carbon in carbon dioxide oxygen is also present in water oxygen is also present. Finally it was proved by the various type of scientists like varnil ruben and kimman and hill reaction. He finally proved that this oxygen came from the water not from the

00:18:00 carbon dioxide. So this is the first proof by the varnil. Instead of using water he used hydrogen sulfide and proved that the hydrogen this is the parall reaction of the photosynthesis. This one is the one reaction. This is the parall reaction. Here there is no use of water. So carbohydrate is in both cases carbohydrate is formed. Glucose is formed in both cases but instead of oxygen sulfur is produced. So varn concluded that oxygen evolved during the photosynthesis. by the photosis of water. This oxygen

00:18:39 when released due to the photosis. What happened in photosis? This is the water lis of water in presence of photon and it converted into proton. It converted into electron and oxygen. So this oxygen came from the water and this process takes place during the light that is called photolyis of water. We can say that lis of water in presence of photon and oxygen is evolved. According to the hill we demonstrate with the help of isolated chloroplast in presence of suitable electron acceptor and photosis

00:19:35 of water according to the hill reaction. He isolated the chloroplast. Chloroplast can be easily isolate. He demonstrated the isolated chloroplast evolved oxygen when they are illuminated in presence of suitable electron acceptor and he use fericanide in absence of carbon dioxide in the hill reaction. Here reaction is known as a part of photosynthesis because in this cases we find that in this reaction the chloroplast is used. Chloroplast is isolated and only light and water is used. There is no carbon

00:20:25 dioxide and oxygen is evolved. So it means that this water release oxygen and when we use fericanide this fericanide is reduced to ferocanide by the photois of water. In photois we have already in earlier reaction during the photois it release proton. This proton is used by the fericanide and it reduced into the ferosanides. So after the hill reaction it is already proved that the oxygen is released during the photosynthesis by the water. There is another scientist that is Ruben and Kimman in 1941.

00:21:17 He confirmed that the oxygen is released not from the carbon dioxide only from the water. He used isotopic study. He used heavy oxygen that is oxygen 18. The oxygen is evolved and proved that varnil's experiment during this experiment this reaction we have written here carbon dioxide water is used here the oxygen used by ruben and carbon that is heavy that is 18 and he found that there is release of starch that is glucose and oxygen is released and after finding it was found that this oxygen is 18 when we are using

00:22:21 here the oxygen is normal 16. So in these cases we can prove that this oxygen 18 released from the yeah evolved from the water not from the carbon dioxide because the carbon dioxide is labeled by 16 and here water is labeled by 18. So these three experiment vanil experiment hill experiment and ruben and kimman experiment proved that the oxygen evolved during the photosynthesis not released by the carbon dioxide only by the water. So this is the used by the ruben and cabin 18 and reported that photosynthesis during the photosynthesis

00:23:08 oxygen come from the water. After that Kelvin the famous reaction that is the dark reaction is also named by Kelvin cycle or C3 cycle trace the pathway of carbon dioxide during the photosynthesis and finally gave the C3 cycle. Next scientist Richard Martin the Nobel Prize winner in 1951 in chemistry on the chlorophyll and other pigment. The whole reaction the whole process of photosynthesis it takes place inside the green plant green leaves that contain various types of pigment that is chlorophyll and

00:23:59 other pigment which we'll discuss. The site of photosynthesis as we have already discussed this is the chloroplast site. This is the leaf upper epidermis. Here is the lower lower epidermis. Two types of parenma are present. That is the the entire is known as misophil. This misophil divided into palisite parenma and is spongy pancama. Inside the par paliset pancayama large number of chloroplast are present or inside the chloroplast photosynthesis takes place and we have already discussed the chloroplast structure

00:24:42 there is presence of thequid estroma and stroma. The mophil cell contain chloroplast chloroplast contain chlorophyll pigment. This pigment is a substance which absorb particular wavelength of light. This particular wavelength of light means that is the visible range of light that our eyes perceive that is violet vure. It absorb light in violet and blue wavelength and the red regions. This is the light range 300, 400, 500, 600 and 700 nanometer. The plant absorb only 400 to 700 wavelength of light. This is called

00:25:40 visible range of light that is violet, blue, blue, green, green, yellow, green, yellow and orange and red. The maximum rate of photosynthesis that is oxygen evolved in the red light. After that this range that is the infrared which are not utilized by the plant as well as human being and below the 400 there is ultraviolet range it is also not utilized by the plant as well as human being only the visible range of light are utilized by the plant for the photosynthesis. This is the chloroplast structure. This is the well-developed

00:26:22 chloroplast structure. This is the stop that is called granom. The one is called taloquite. This is the outer membrane. The inner membrane inner membran space in talaquad. All the enzymes are present for the photosynthesis. For light reaction in stoma dark reaction takes place. We have already discussed double membrane structure of the chloroplast. Here is the stoma. Esttoma is the site of a dark dark reaction. Into circular DNA RNA and 70s ribosome are present. The laminar system with the stoma form

00:27:07 taloquids. This is the structure of a chlorophyll molecules where the photosynthesis takes place. Chlorophyll molecules. The structure of chlorophyll molecules. It is just like a tennis racket. The tennis racket. We have already seen here is a circular ring like a structure at the head that is called power firing ring and the hand of tennis racket. Here is the tail of chlorophyll that is called phal tail. The chlorophyll molecules are made by head and tail. Head is made by perfining ring and tail is called phal

00:28:16 tail. It is just like a tadpole like structure that is the fog larva. The perfin ring consist of four parall ring. Here the four parallel rings are there. And this ring contain nitrogen and centrally placed magnesium. Just like hemoglobin, the perfin ring consist of four parallel ring. One, two, three and four. And each parallel ring made by nitrogen as well as carbon dioxide ring are attached with each other by methane bond. This methane bond are made by carbon hydrogen. Here is a double bond. Okay. The perfaren head consist of

00:29:23 four parallel ring linked together by the methine CH. The carbon is attached by the one and here is the double bond structure form the ring system. Each parallel ring composed of four carbon 1 2 3 four carbons and one nitrogen. These are the nitrogen we have already discussed this nitrogen this nitrogen this nitrogen and this nitrogen. So the each perfin ring are made by five membered ring. Five member out of five member one it is nitrogen and four it is carbon. carbon 4 and each ring contain centrally core magnesium

00:30:13 group. A side chain of that is the phal chain extend from one of the parallel ring. Out of this parallel ring, one paral is going to be extended and the phal tail. The phital tail is made by 20 carbons. This fital 20 carbons are attached to the seven of the paral ring of fourth. This one is the fourth carbon. Fourth members and the 20 carbon attached here with the propionic acid easter bond. The there are large number according to the fridge there are 11 type of chlorophyils are there. chlorophyll A, B,

00:31:04 C and so on. But two main chlorophylls are there which is which mainly help in the photosynthesis that is the chlorophyll A and chlorophyll B. More or less the structure of chlorophyll A and chlorophyll B is similar but there is slightly different. Chlorophyll A differ from the chlorophyll in the nature of group attached at the three. The third member of the paral ring. Chlorophyll A has methile group while the in chlorophyll B there is here is the methile group is there. Here is aldahhide group is there.

00:31:55 Now we can discuss about the different types of chloroplast pigment. Yeah. Chlorophyll pigment. The chloroplast contain the large number of pigment that is mainly chlorophyll, carotenoid and ficlines. The chlorophyll and carotenoids which are present in the higher plant and foblene which is found in the lower group of plant like syinoacteria that is the blue green algae and rodopyic. Here we have slightly details about the chlorophyll and other pigment. Chlorophyll the main I have already tell different type

00:32:36 of chlorophyils are there but here we discussed only chlorophyll A chlorophyll B chlorophyll C and chlorophyll D and bacterial chlorophyll carotenoids are divided into two groups that is carotin and genophil the chlorophyll A which is most abundant in the green plant. It is found in the higher plant as well as green plant. Its molecular formula is C 55 H72 05 N4 Mgz and chlorophyll B similar that it is also made by C 55 H70 O6 N4 Mg we have already discussed magnesium ion is centrally placed and

00:33:45 four nitrogen groups are there in the form of paral ring here also magnesium ion four paral ring nitrogen here the difference is here here is hydrogen is 72 here hydrogen is 70 here oxygen is five oxygen is six okay the chlorophyll generally it is blue green green color, blue green color and the most important things it absorb the light 430 to 660 nanometer wavelength of light. Chlorophyll A receive that finally shows the action spectrum and action spec absorption spectrum. Also the blue green algae receive 430 and 6 maximum range of

00:34:39 the 660 nanometer wavelength of light in the chlorophyll be here is the molecular formula is it is generally yellow green color and it also received the wavelength 555 nanome to 644 nanometer wavelength of light. This one is the lowest one. This one is the highest one. And in this range the chlorophyll B release oxygen evolved oxygen and rate of photosynthesis depend upon the this range. Beside this there is the chlorophyll C which molecular weight is molecular formulas C5 H 92 05 N4 mg. So in all these cases we

00:35:44 find that there is a magnesium and nitrogen is common. Now there is beside the the chlorophyll D which is dominant pigment in the rodtoacy member. It is also green in color. Here the range is 447 to 688. It is find in the red bacteria chlorophyll which is color is pale blue color. It is mainly found in the green sulfur bacteria and purple sulfur bacteria where during the photosynthesis that is called chemosynthesis. Instead of water there is use of hydrogen sulfide. Now the another pigment that is

00:36:27 carotenoids that contain carotin and genophil is the molecular formula is C40 H56. It is orange in color. The range of receiving light is 450 to 460. It is found in algae and higher plant. And genill it is also found in the algae and higher plant. Beside this the foblene which is found in the lower algae that is also divided into ficoythine and ficoinine. Both color is red. Show dominant. Sir, can we ask a question? Sir, uh, chlorophyll C, is that C54 or C35? C35, sir. C3 sir. Uh, thank you sir. Here the formula of

00:37:28 uh chlorophyll C is C35 H 32 05 N4 mg sorry that is the correct formula. Okay. Okay. H32. Okay. H32. Okay. So here is the main structure of chlorophyll. Here's the magnesium ion nitrogen here. And in the second parallel ring here is a methile group or instead of group field B methile group is replaced by here we see that the there is a different range of the light absorbed. This is the spectrum of chlorophyll A. Here is the wavelength and the amount of light absorbed. This is the range. Here we

00:38:35 find that the chlorophyll B absorbed may more light amount of light in comparison to the chlorophyll A and cotton wide. Also the maximum range of the chlorophyll A here is the 700 approximately 700 nanometer and in chlorophyll B just below the 700 650 640. This graph shows the two type of a spectrum that is absorption spectrum as well as action spectrum. The portion of visible light that I have already told that is a 400 to 700 nanometer that is also called PAR photosynthetically active radiation.

00:39:34 This shows two graph that is absorb absorption spectrum a curve reflecting the amount of light absorbed by the pigment at each wavelength. So when we plot the graph like this in xaxis and y-axis here is the wavelength of light. Here is the amount of light absorbed. when the amount of light absorbed by the particular pigment that graph shows the absorption spectrum. There is another graph the rate of photosynthesis against the wavelength. The actual rate of oxygen evolved that is actual rate of oxygen evolved means

00:40:30 rate of photosynthesis. Huge amount of oxygen evolved during the photosynthesis. It means the rate is very high. The actual rate of oxygen evolved and carbon dioxide consumed during the photosynthesis. it plotted against the wavelength that gives action spectrum. Now the question is there are large number of pigment chlorophyll pigment as well as kerotin and other pigments are there. The all other pigment except the center molecule that is that reaction center it also involved in photosynthesis it receive lower

00:41:12 wavelength of light. This lower wavelength of light received by the particular pigment and finally this wavelength of light it gives to the reaction center where the reaction is going to be start that is electron is released and this electron is accepted by the different types of acceptor that is called primary acceptor. When this different type of molecules that is called also called antenna molecules. These antenna molecules it receive lower wavelength of light. And finally the reaction this receive the lower

00:42:03 wavelength of light. And finally this energy passes to the reaction center. When the reaction center receive the particular wavelength of light that is able to release the electron. This electron is going to be released when any molecules according to the Einstein photoelectric effect. When any molecule receive energy, it release electron and this molecule which receive energy now come in the excited state. In the same fashion the chloroplast pigment which have large amount of pigment large amount of

00:43:03 molecules that is called antenna molecules it received particular wavelength of light and now comes in the excited state. Any molecules doesn't want continue to be in excited state. It wants to be in ground state. For coming in the ground state here the water is going to be break down and sufficient amount of light is here. This water release proton electron and oxygen. This electron released by the water. This electron came here. This electron received by the reaction center that is the pigment system. And now we

00:44:07 come in the ground state. after receiving the so this reaction also called photosis of water. photosis of water and the release of electron which help in the reaction center molecule come in the ground state and this electron which is released by the reaction center or the main pigment it is accepted by primary acceptor and this oxygen act as a byproduct which is released in the environment and the proton are received by various type of co-enzyme like NAD nicotenomide adinine duclotide phosphate and it combined with the

00:45:11 proton and it converted into N A PH2 2 which gives assimulatory power for the photosynthesis. This NADPH2 that is called reduced co-enzyme. And finally this reduced co-enzyme when the reaction when the reaction require hydrogen this NADPH2 release hydrogen and reaction is going to be start here the chlorophyll is responsible for involving the light energy and converting into the electrical and chemical energy. So they call reaction center. Here is the reaction center. Chopil B molecule is acting as a

00:46:17 accessory pigment help to broaden the spectrum of the absorption of the light. Chlorophyll B. Beside the chlorophyll there are the another pigment carotin and other small molecules which receive particular wavelength of light and finally it gives to the reaction center to start the reaction. Now there are mainly two type of reactions are there. The light reaction and dark reaction. This light reaction we have already told these reaction require this NADPH2 and ATP. This ATP and NADPH2 which release in the light

00:47:03 reaction. And combinely these both is called assimulatory power which help in the reaction that is called right reaction. In stroma as we have already told during the chloroplast theoquide and estro are there. For dark reaction all the enzymes are present in the estroma. Dark reaction not dependent upon the light so it is called dark reaction. Light reaction takes place in the light so it is called light reaction. Here the summarized form of the light reaction. This is the antenna molecules reaction center primary

00:48:02 acceptors. Here two type of pigment system as already scientist discovered after the flashing of light light and direct reaction. This antenna molecule received light and release electron. These electron are accepted by a compound known as ferodoxine. This feroxin release the electron and received by this electron to plastoenone. After the plastoon the electron release and it is accepted by cytochrome complex then plastosin. after the plastosyine this electron returned back to the reaction center. So

00:48:50 in these cases we find that the electron is released and finally it enter into the reaction center. So this type of reaction, this type of light reaction is called cyclic because it formed the cyclic way. Electron release here and again came back to the pigment system 700. In this process in cytochrome complex here ADP ad honosphate is converted into ATP. Formation of ATP that process is called phosphorilation. Here the ATP is formed with the help of light that light absorbed by the antenna molecules as well as the core molecules.

00:50:10 So this phosphorilation is called phototophosphorilation because ATP is formed with the help of photon. So here the electron coming from the reaction center P700 return back to the P700. So this type of phosphorilation is also called cyclic phosphorilation. So in light reaction though two type of phosphoration takes place. Cyclic phosphorilation and non-cyclic phosphoration. This cyclic phosphoration it require the primary accector paradoxine plastoon cytochrome then plastosin and return back to

00:51:12 the there is another type of phosphorilation also there that is called non-cyclic phosphorilation. In non-cyclic phosphorilation two type of pigment system are involved that is pigment system two that absorb lower wavelength of light that is P680 and another pigment system that is pigment system one. It received maximum 700 wavelength of light. During the daytime when light is present the antenna molecules as well as the other molecule it receive the particular wavelength of light and finally it goes to the pigment system

00:52:11 too that is P 680. This P680 when energy is received it come in excited state and finally it release electron. Now after the releasing electron it came in excited state and this excited state fulfilled by photosis of water that is oxygen is released as a byproduct. proton is received by the NADP and finally converted into NADPH2 and this electron are received by pigment system second. This pigment system now come in the ground state. Now in the another cycle that is called non-cyclic phosphoration. This primary

00:53:17 acceptor this electron transferred to the plastoinon that is PQ and from the plastoon the electron goes to cytochrome complex. from the cyto complex which release ATP as we have already discussed in cyclic ADP plus inorganic phosphate it converted into ATP from the cytochrome complex the electron goes to plastosin and from the plastosin it goes to pigment system first when the pigment system first receive electron It already released the electron when receiving P700 700 wavelength of light. After receiving P700 wavelength

00:54:16 of light, it comes in the excited state. Now it is fulfilled by the electron received from the plastosin. Now this electron which is released from the pigment system first it is received by paradoxin. This paradoxin release electron to nadp and this electron and here is the proton. Finally this proton and the electron combine and this NADP is converted into N APH2. Here things is very common to the cyclic phosphorilation that is ATP is released. So this process is called phosphorilation. But one thing is different that the

00:55:29 electron released from the pigment system two not coming back to the pigment system two. It goes to the pigment system one and from the pigment system one to the NADP2. So the electron is not able to return same type of reaction center. So this type of phosphorilation is called nonyclic. So there are two type of phosphorilation there. Noncyclic phosphoration as well as cyclic phosphoration. The difference is there in non-cyclic phosphoration two pigment system are involved that is pigment system one and pigment system two.

00:56:14 But in case of cyclic phosphoration only one pigment system involved that is PS1 P700. In both cases ATP is for. So these are the common things between the cyclic and nonclic phosphorization and the difference is that this NADPH2 this one and this one ATP which is released in the light reaction called assimulatory power already discussed these are used in to fix this NADPH2 and ATP which used to fix the carbon dioxide. into carbohydrate. This is the reduction process because carbon dioxide it accept

00:57:09 hydrogen and converted into glucose molecule that finally gives starch. So this reaction takes place in dark without use of light. So the carbon dioxide reduced to carbohydrate this is going to be dark takes place in the dark reaction or this reaction require NADPH2 as well as ATP which I will discuss in the next chapter. Okay. Thank you. [Music]