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Class 7, Science, Chapter 1 Nutrition in plants
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Introduction to Nutrition in Plants, ● Living organisms like human, beings, plants and animals need, food to survive and exist., ● Living organisms reproduce,, respond to the environment and, also adapt., ● Living organisms respire and, excrete as well.
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Cells, Cells are tiny units that help make up a, living organism. Hence, they are also, called building blocks of an organism., A cell is constituted of three major parts :, ●, ●, ●, , A thin outer layer called the cell, membrane., A spherical structure located at the, centre of the cell called a nucleus., A jelly-like substance that, surrounds a nucleus called the, cytoplasm.
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Cell
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Single and Multi-Cellular Organisms, ●, , ●, , ●, , Organisms that are made up of, just one cell are called, single-celled or Unicellular, organisms. E.g. Amoeba, Organisms with more than one, cell in their body are called, multicellular organisms., All human beings, plants and, animals are multicellular, organisms.
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Nutrition, Nutrition is the mode of taking food by an, organism and its utilisation by the body., , ●, , ●, ●, , Nutrition is very important as the, nutrients from the food consumed, enables living organisms to build their, bodies and grow., Nutrition helps to repair damaged parts, and organs., Nutrition also provides energy for, carrying out various functions.
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Autotrophs and Heterotrophs, ●, ●, , ●, ●, , Organisms that make food themselves are, called autotrophs, Plants are an example of autotrophs as they, make their own food using carbon dioxide,, water and light energy., , Organisms that rely on others and usually, take in ready-made food made by the, autotrophs are called heterotrophs., Animals and human beings are an example, of heterotrophs as they depend on plants in, many ways for their food.
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Photosynthesis, ●, , ●, ●, , Photosynthesis is the process, of synthesis of food by green, plants., This process usually takes, place in the leaves of plants., The process requires, chlorophyll (green coloured, pigment), sunlight, carbon, dioxide and water.
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Organelles, ●, , ●, ●, , Organelles are tiny cellular, structures inside a cell and, perform specific functions that, are important for the cell., They are found in the cytoplasm, of a cell., E.g. Chloroplast is the cell, organelle that carries out, photosynthesis.
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Chloroplasts, ●, , ●, , The chloroplast is a type of, organelle that exists in, plants., These organelles contain, chlorophyll, the green, coloured pigment that is, responsible for carrying out, the process of, photosynthesis in plants
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Chlorophyll, ●, , ●, , ●, , Chlorophyll is the pigment that, is responsible for the, synthesis of food in green, plants., This pigment green colour to, its bearers and is abundantly, found in leaves., Chlorophyll is locked inside, the chloroplast.
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Process of Photosynthesis, ●, ●, ●, ●, , ●, , The process of photosynthesis takes, place in the leaves, the “food factory” of, the plants., Carbon dioxide is taken in through tiny, pores on the leaves called stomata., Water and minerals that are required for, the process are transported to the leaves, from the roots through the stem., Chlorophyll helps the leaves use the, energy from the sunlight to prepare food, using the carbon dioxide, water and, minerals., Oxygen is released as a by-product of, this process.
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Nutrients Being Replenished in Soil, ● Plants absorb mineral nutrients from the soil in order, to make their own food and for other important, processes., ● Soils need to be enriched with nutrients such as, nitrogen, phosphorus, potassium etc regularly., ● Only then can we grow plants and keep them, healthy.
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Other Modes of Nutrition, Symbiotic Relationship, ●, ●, ●, , ●, , Organisms that live together and share, their shelter and nutrients are said to, be in a symbiotic relationship, Certain fungi live in the roots of trees., The tree provides nutrients to the, fungus and, in return, receives help, from it to take up water and nutrients, from the soil., This association works well for both the, fungi and the tree
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●, ●, ●, , Another most common example is of Rhizobium bacteria., They reside in the root nodules of leguminous plants., The bacteria provide a plant with nitrogen that they fix and in turn,, they get shelter and food from the plant, , Rhizobium, ●, ●, , Rhizobium is a type of bacteria that convert atmospheric nitrogen, into a soluble form that can be utilised by plants (nitrogen fixation)., It usually resides in the roots of leguminous plants like peas, gram,, moong etc and is instrumental in providing these plants with a rich, source of nitrogen.
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Nitrogen fixation, ●, ●, , ●, , Nitrogen is an important nutrient, required for soil and for plants., However, nitrogen in the, atmosphere is not easily, accessible., The process by which nitrogen, is converted into a form that can, be used by plants and other, living organisms is called, nitrogen fixation.
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Parasite, ●, ●, ●, ●, , A parasite is a heterotroph that, completely depends on another, organism for its food., The organism to which the parasite, latches onto is called the host., The host, in the process, is deprived of, all nutrients for its own growth as they, are consumed by the parasite., For example, Cuscuta (Amarbel) is a, nongreen plant that takes readymade, food from the plant on which it is, growing
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Saprotrophs, ●, , ●, ●, ●, , ●, , Organisms which rely on dead, and decaying matter for their, food are called Saprotrophs., This mode of nutrition is called, saprotrophic nutrition., For example, Fungi., Fungi secrete digestive juices on, the dead and decaying matter and, convert it into a solution., Then they absorb the nutrients, from it.
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Insectivorous plants, Plants that feed on insects are, called Insectivorous plants., ●, ●, ●, ●, ●, , These plants are green and carry, out photosynthesis., But, they grow in nitrogen-deficient, soils., So, in order to get nitrogen, they, feed on insects., These insectivorous plants have, their parts modified for attracting, and catching insects., For example, The pitcher plant,, Venous flytrap
