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Class 7 Science: Chapter 1 – Nutrition in Plants, Question1. Why do organisms take food?, Solution1:, Living organism eat food to get energy, which is essential for performing growth and, maintenance of their body., Question2. Distinguish between a parasite and a saprotroph., Solution2:, Saprotroph, 1) These are the organism that takes nutrients from the dead or decaying organic matter., 2) Example: Fungi, Parasite, 1) These are the organism that grows and feeds on a living organism., 2) Example: Cuscuta, Question3. How would you test the presence of starch in leaves?, , Solution3:, Iodine solution is used to test leaves for the presence of starch., In order to perform this test, one needs to heat the plant leaf in boiling water for 30 seconds to 1, minute and after that heat in boiling ethanol for a few minutes. Wash with water and spread onto, a white tile and add a few drops of iodine solution. The parts of the leaf that contains starch will, change its colour blue-black., , Question4. Give a brief description of the process of synthesis of food in green plants., Solution4:, Photo means light and synthesis means to combine. Photosynthesis is the process by which, plants prepare their food. In this process green pigment in plants (known as chlorophyll) helps, leaves to capture the energy of the sunlight. This energy is used to synthesise (prepare) food, from carbon dioxide and water.