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How is photosynthesis done |
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Answer» Photosynthesis involves two types of reactions namely, light reactions and dark reactions.a) Light reactions: Light reactions are light dependent reactions. These reactions happen only in the presence of sunlight. The photosynthetic pigments trap the energy from the sunlight. PS-I and PS-II collectively bring in the cyclic photophosphorylation and non-cyclic photophosphorylation reactions. As a result of these reactions energy rich molecules like ATP and NADPH2\xa0are synthesised. Photolysis of water molecules results in the release of oxygen as a by-product. H2O → 2H+ + 2e- + ½O2b) Dark reactions: Dark reactions are independent of light. Energy rich molecules like ATP andNADPH2 are utilised in these reactions. Dark reactions involve Calvin cycle during which carbon dioxide is reduced to carbohydrate.C3 pathway is also known as Calvin cycle.C3 pathway involves set of carbon reactions which are catalysed by the enzyme Rubisco to synthesise 3 carbon compound, 3-phosphoglycerate from 5-carbon compound, Ribulose bisphosphate.\tRibulose bisphosphate is the primary acceptor of CO2.\tChloroplasts present are only of one type.\tAnatomy of leaves does not resemble Kranz anatomy.\tPhosphoglyceric acid is synthesised as the product.\tMesophyll cells exhibit Calvin cycle.\tPhotorespiration is observed.\tOptimum temperature required for photosynthesis is between 20 degree celsius\xa0to 25 degree celsius.\tThis cycle is less efficient in utilising CO2. Chlorophyll recives the light from the source which is sun and converts it into chemical energy and uses it in spliting of water moleculs into H(hydrogen) and O (oxygen ) it also is used in reduction oh carbondioxide to carbohydrates . The realease of energy is done in mitochondria . The conversion of light energy into chemical energy is done actually done in Grana which is present in chloroplast the because of this ATP and NADPH are formed . Then now we can say that the materials from atmosphere are taken up and are made them as stored forms of energy whis is called as photosynthesis. The bi products of photosynthesis are water and oxygen and the end product is starch. |
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