what is photosynthesis ?
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"Photosynthesis is the process used by green plants where they convert light energy into chemical energy."
Green plants are autotrophic and synthesise their own food by the process of photosynthesis. The green plants make their own food from simple inorganic substances like carbon dioxide and water in the presence of sunlight. The plants use the energy in sunlight to prepare food in the presence of a green coloring matter called chlorophyll present in the leaves of the plants. So, the process of photosynthesis takes place in the leaves of a plant. Oxygen gas is produced during photosynthesis. This oxygen goes into the air. The oxygen gas released in photosynthesis is utilised by all the living organisms for their survival. The process of photosynthesis first produces a simple carbohydrate called glucose as food . The glucose carbohydrate then gets converted into a complex carbohydrate called starch. This starch gets stored as food in various parts of plant including leaves. In fact, the presence of starch shows the existence of photosynthesis in a plant. Some of the glucose is also converted into other types of plant foods such as fats and oils, proteins as well as vitamins. The synthesis of food occurs in the leaves of a plant. So leaves are the food factories of a plant. The leaves of a plant can synthesise food because they contain a green pigment chlorophyll. Now let us know how the plants obtain carbon dioxide for photosynthesis. The plants take carbon dioxide gas needed for photosynthesis from the air. The plants take carbon dioxide gas from air through the tiny pores called stomata present on the surface of leaves. Actually there are a large number of tiny pores called stomata on the surface of leaves of plants. Each pore or stoma is surrounded by a pair of guard cells. The opening and closing of stomatal pores in the leaves is controlled by the guard cells. The carbon dioxide gas present in the air enters through the leaves of a plant through the stomatal pores present on their surface and utilised in photosynthesis. The oxygen gas produced in the leaves during photosynthesis goes out into air through the same stomatal pores. The stomatal pores of leaves open only when carbon dioxide is to be taken in or oxygen is to be released otherwise they remain closed. ,. How the plants obtain water for photosynthesis. The plants take water needed take water needed for photosynthesis from the soil. Soil always contains some water in it. Water present in the soil is absorbed by the roots of a plant and then transported to the leaves through the vessels which run like inter connected pipes through out the roots, stems, branches and leaves. Chlorophyll absorbs light energy from the sun and supplies this energy to the leaves to enable them to carry out photosynthesis for making food. Since the combination of carbon dioxide and water to make food like glucose occurs in the presence of sunlight the process is called photosynthesis photo equal to light and synthesis equal to to combine. In conclusion,the presence of carbon dioxide water, chlorophyll and sunlight is necessary for the process of photosynthesis to take place. Photosynthesis cannot occur in the absence of anyone of these conditions.