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CHAPTER – 1 Nutrition inplants Nutrition: It is themode of taking food by an organism andits utilization bythe body. Nutrients: The components of food thatprovide nourishment tothe body. All organisms take food and utilise it to get energy for the growth and maintenance of their bodies. Green plants synthesise their food themselves by the process of photosynthesis. They are autotrophs. Photosynthesis: Green plants prepare their own food with the help of chlorophyll (found in green plants), carbon dioxide and water taken from the environment in presence of sunlight . This process is known asphotosynthesis. Plants use simple chemical substances like carbon dioxide, water and minerals for the synthesis of food. Chlorophyll andsunlight are theessential requirements forphotosynthesis. Complex chemical substances such as carbohydrates are the products of photosynthesis. Solar energy isstored in theform of foodin the leaves with the helpof chlorophyll. Oxygen is produced during photosynthesis. Oxygen released in photosynthesis is utilised by living organisms for their survival. Fungi derivenutrition from dead,decaying matter. Theyare saprotrophs. Plantslike Cuscuta areparasites. They takefood from thehost plant. A fewplants and allanimals are dependent on others fortheir nutrition andare called heterotrophs. Parasitic: Organisms that live on the body of other organisms. Allparasitic plants feedon other plants as either: (i) Partial Parasites: Obtain someof their nutrition from the host,e.g. painted cup (ii) Total Parasites: dependent completely onthe host fornutrition, e.g. mistletoe. Saprophytic: Organisms that obtain nutrition from deadand decaying plantand
animal matter. Mushrooms, moulds and certain types of fungi and bacteria. Insectivorous Plants: Green plants which obtain their nourishment partly from soil and atmosphere and partly from small insects. Example: pitcher plant, bladderwort, and venusfly trap. Symbiosis: Mode of nutrition in which two different individuals associate with each other tofulfil their requirement of food. Lichens foundon tree trunks is the association between algae andfungus. Algae obtains water fromfungus and itin turn obtains food from algae.
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