Photo Synthesis

PHOTOSYNTHESIS DEFINITION OF PHOTOSYNTHESIS: Photosynthesis is a process by which green plants prepare their food (starch) with the help of atmospheric carbon dioxide and water in the presence of sunlight and chlorophyll. photosynthesis: in the process of respiration, which is a natural and Essential phenomenon in all living beings , oxygen is inhaled and carbon dioxide is exhaled to the atmosphere. The atmospheric carbon dioxide is absorbed by the plants during the process of photosynthesis and oxygen is given out. Thus plants help to preserve the balance of gases in the atmosphere.

EXPERIMENT: Take a big sized beaker and put any water plants in the beaker and fill it with water. Take a funnel and invert it over the water plants .now, fill a test tube completely with water and invert it over the funnel such that water remains standing in the test tube. Keep the whole apparatus in bright sunlight for few hours. What do you observe? We will observe that some air bubbles move up the teat tube and collect at the top part of the inverted test tube. now remove the test tube by putting the thumb at the mouth of the test tube so that air inside the test tube cannot Escape out. Next, invert the test tube to make its mouth up. The water settles down in the bottom and the gas comes above it. Now, bring a glowing match stick in the tube after removing the thumb from its mouth. Do you see any change in the glowing of the match stick? The match stick bursts into a flame which indicates the presence of oxygen. This oxygen is given off by the plant during the process of photosynthesis.

Experiment: Pluck a green leaf from a plant. Put it in a beaker containing boiling water for 10-15 minutes. Now transfer the leaf to another beaker containing alcohol and boil slowly for few minutes .the leaf would become white because of the removal of chlorophyll. Place the leaf in a dilute solution of iodine containing a little saturated solution of chloral hydrate. The chloral hydrate will make the leaf transparent and the leaf turns bluish black select any potted plant having long leaves. Remove its starch by putting the plant in a dark place for three or four days . Pluck a leaf from the plant and insert half of it in a bottle through a split cork. Some concentrated potassium hydroxide solution has already been kept in this bottle .potassium hydroxide will obsorb all the carbon dioxide presentin the bottle . Now keep the apparatus in sunlight . Examine the leaf for starch after 5 to 6 hours with iodine solution. Do you observe any difference between two parts of the leaf? Why is it so? Only half part of the leaf which was outside the bottle shows bluish black colour. This is because this part received car bon dioxide from the atmospheric air. While the part inside the bottle did not receive carbon dioxide and hence did not show any colouration.

We Know That Green Plants Are Autotrophic And Propane Food By The Process Of Photosynthesis. DEF:It Is a process in Which Plants Use Sun Light And Chlorophyll to Synthesis Food Utilsing CO2 And H2 O . The Chemical Equation of Photosynthesis is 6co2+12H2O Sun light C6H12 O6 +6 H2O+6O2 Chlorophyll glucose. HOW :Solar energy traps :chlorophyll And Carodendid pigments Are present in the plants .these are photoreceptor molecules .there are different type of chlorophyll like a ,b,c,d, and .most common are a s b.light energy Received from sun is fixed and controlled by chlorophylls.

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Site of photosynthesis: (A) Plastids (chloroplast) Chlorophyll pigments are present in cell organelles ,called ,plastid .In the cross section of loaf .they can be seen easily .below the upper epidermis in a tissue ,called palisade (B) Grana: in the chloroplast of higher plants ,stacks of lamellar structures called grana (C) Stroma: the inner membrane lines the lumen of chloroplast ,called stroma

(D) Stroma lamellae: in the cross section of the grana, hyracoid of one geranium is connected to the other by a membrane called lamella.

ROW martial for photosynthesis: carbon chloride (co2) and water (H2O)Is used as a row material in photosynthesis .co2 enters the leaf through the stomata present on the sun face of leaf . Water is absorbent through osmosis and transported upward by xylem. Comentionpoint: when the in tensely of light is low, the amount of co2 released equals its consumption .by photosynthesis process. Mechanism of photosynthesis: the entire process of photosynthesis combed divided into two main stages. 1. Cite reaction: chlorophyll molecule after being exposed to light gets excited and admits election. The emitted travel through chloroplast there fore ATP is synthesized from ADP and in organic phosphate in light reaction photolysis of water a takes place. 2. H2O______ 2H+1/2O2+2e Dark reaction: the released H+ In light Reaction reduces NADP Molecule into NADPH. Now NADPH and ATP molecules are utilized in the stoma of chloroplast for synthesis of lo2 s H2O. This is called dark section. In This process co2 enters into a cycle of reactions starting from repulse disphospnate .at the and carbohydrate is synthesized and repulse phishosphate is rage rated .it s also called Calvin –Benson cycle. Question: 1. Define photosynthesis? 2. Define the following terms __:

1. Chloroplast 2.grana 3. Stroma. Q 3: name the pigments which can absorb sun light? 4. What is the row material for photosyn? 5. Define com pensation point? 6. Give the mechanism of photosynthesis?

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