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Revision Notes, Class – 11 Biology, Chapter 12 – Mineral Nutrition, , Mineral Nutrition, Definition of mineral nutrition in plants:, Carbohydrates, proteins, lipids, water, and minerals are required for all living, creatures to survive. Plants, too, require nutrients for growth and development., Methods to study the mineral requirement of plants, Hydroponics is a method of growing plants in nutrient solutions rather than soil., This method is employed in the commercial cultivation of vegetables. It's also used, to research plant mineral deficiency disorders., Aeroponics is a method of growing plants by spraying nutrients floating in the air., Essential mineral elements, a) Mineral needs vary depending on the plant. There is a criterion for determining, whether or not an ingredient is necessary., b) It contains the following items:, • The element must be required for proper development and reproduction. If such a, component is missing, the, • Plants won't be able to finish their life cycle., • The element's need must be precise, and no other element should be able to, substitute it., • The element must play a direct role in plant metabolism., There are two types of mineral elements required by plants: macronutrients, and micronutrients., Class XI Biology, , www.vedantu.com, , 1
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Macronutrients, The plants require a high amount of these components. Carbon, hydrogen, oxygen,, nitrogen, phosphorus, sulphur, potassium, calcium, and magnesium are all found in, it. CO2 and H2O are the most common sources of carbon, hydrogen, and oxygen., Others are received as mineral nourishment from the soil., Micronutrients, These are the nutrients that plants require in tiny quantities. Iron, manganese, copper,, molybdenum, zinc, boron, chlorine, and nickel are all present., Essential elements, (1) Essential elements like carbon, hydrogen, oxygen and nitrogen serve as, components of numerous biomolecules such as amino acids, lipids, and therefore, structural elements of cells and are classified into distinct groups depending on their, unique activities., (2) Essential elements, such as magnesium ion in chlorophyll and phosphorous in, ATP, are key components of chemical compounds associated with energy., (3) Essential elements operate as both activators and inhibitors of enzymes,, influencing their function. Both ribulose bisphosphate carboxylase oxygenase and, phosphoenolpyruvate carboxylase are activated by Mg2+. Both of these are required, for carbon fixation to occur. During nitrogen metabolism, Zn2+ activates alcohol, dehydrogenase, while Mo is required for nitrogenase activity., (4) The osmolarity of a cell is controlled by a few key components. The stomata, open and close in response to potassium ions., Role of macronutrients and micronutrients, The role of different macro and micronutrients areNitrogen, • Plants require a considerable amount of this essential ingredient., • It is taken by plants as nitrate ions (NO3), with certain plants also absorbing it as, nitrite ions (NO2) or ammonium ions (NH4)+., , Class XI Biology, , www.vedantu.com, , 2
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• It is an essential component of vitamins and is required by plants for actively, developing tissues such as meristematic tissues., • Plays a direct role in photosynthesis., Phosphorus, • Phosphate ions (PO4)3+ are absorbed by plants., • It is found in large quantities in cell membranes, proteins, nucleic acids, and, nucleotides., • Encourages the development and growth of roots., • Seed formation needs the presence of this nutrient., • Involved in the storage and transport of energy., Potassium, • It is rich in actively developing tissues such as meristematic tissues, buds, leaves,, and root tips., • It is necessary for sustaining osmotic potential in a cell that is responsible for, stomatal opening and closing., • Increases photosynthetic rates., • The protein synthesis is dependent on it., Calcium, • Calcium ions (Ca2+) are absorbed by plants and are required for ongoing cell, division and development., • Plays a part in nitrogen metabolism., • It exists in the form of calcium pectate in the middle lamella., • It is also necessary for the mitotic spindle to develop., • It is also necessary for the activation of certain enzymes., Magnesium, Class XI Biology, , www.vedantu.com, , 3
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• It is necessary for the activation of enzymes involved in respiration and, photosynthesis., • It is absorbed by plants in the form of magnesium ions (Mg2+)., • It aids in the production of RNA and DNA., • It's a crucial component of chlorophyll, as well as maintaining ribosome structure., Sulphur, • An essential component of amino acids like methionine;, • An essential component of amino acids like methionine;, • Contributes to seed production, • It is necessary for chlorophyll creation, Iron, • Iron is absorbed mostly in the form of ferric ions (Fe3+) by plants and is necessary, for cell division and development., • Assists in the transport of electrons during a variety of metabolic processes., • It is necessary for the activation of the catalase enzyme, which is essential for, chlorophyll synthesis; it also functions as an oxygen transporter., Manganese, • Manganese is absorbed in the form of ions (Mn2+)., • One of the components of the nitrogenase enzyme, which is essential for nitrogen, metabolism., • It is engaged in the photolysis of water during non-cyclic photophosphorylation., Zinc, • Zinc ions (Zn2+) are absorbed by the body., • Essential for the production of chlorophyll., • Plays a role in the activation of numerous enzymes, including carboxylases., Class XI Biology, , www.vedantu.com, , 4
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• Required for carbohydrate synthesis., Copper, • It is absorbed in the form of cupric ions (Cu2+) by plants., • During metabolic processes, it is engaged in redox reactions., • Performs photosynthesis and reproductive functions in plants., • Contributes to the flavor of fruits and vegetables., • Increase the amount of sugar in the plants., Boron, • Boron is absorbed in the form of BO33 or B4O72- by the plants., • It plays a role in calcium absorption., • Assists in the development of pollen tubes., • Plant carbohydrate transport, • Plays a part in cell differentiation., Molybdenum, • It is obtained by plants as molybdate ions (MoO2)2-., • Nitrogenase enzyme's main component. It, together with iron, forms the enzyme's, catalytic site., • It's a crucial part of the nitrate reductase enzyme. Nitrate reductase is a nitrogen, assimilation enzyme, • Nitrate reductase is a nitrogen assimilation enzyme that also plays a role in nodule, development., Chlorine, • Ions of chloride are absorbed (Cl1-)., • Maintains the cell's osmotic potential., Class XI Biology, , www.vedantu.com, , 5
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• It is engaged in the photolysis of water, which results in the production of oxygen., Deficiency Symptoms of Essential Elements, • One of the most crucial necessary elements is nitrogen. Yellowing of the leaves is, caused by a nitrogen deficiency., • Phosphorus shortage results in burned leaf tips and yellowing of the tips., • Potassium shortage results in interveinal chlorosis and wilting of older leaves., • Blossom end rot is caused by a calcium shortage., • Magnesium causes older leaves to become yellow, a condition known as chlorosis,, which occurs when chlorophyll is degraded., • Sulphur shortage causes younger leaves to yellow more than older ones., • Chlorosis of young leaves is caused by an iron deficit. Dieback disease is a common, symptom of an iron shortage in plants., • Manganese causes yellowing between the veins of the leaves and creates dead, patches on plant components., • Zinc causes the plant to develop rosettes, yellowing between the veins, and reduced, growth., • Copper shortage results in the weakening of cell walls, as well as stem and twig, dieback., • Boron has an effect on plant reproductive and vegetative development, as well as, meristem death., • Molybdenum causes growth retardation., • Chlorine produces wilting, chlorosis, and a highly branching root system, as well, as necrosis in the tissues., Metabolism of nitrogen, Nitrogen is made up of two nitrogen atoms that are linked together by a triple, covalent bond (N ≡ N). Nitrogen fixation is the process of converting nitrogen into, ammonia., Class XI Biology, , www.vedantu.com, , 6
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The conversion of nitrogen to ammonia can be done in two ways. The following are, the details:, • Physical nitrogen fixing happens when lightning strikes. In the presence of, lightning, N2 and O2 in the atmosphere react to create nitric oxide (NO). NO is then, oxidised further to create nitrogen peroxide (NO2)., • Ammonification is the process of producing ammonia from the decomposition of, dead plants and animals. Nitrification is the process of converting ammonia to nitrite, and ultimately to nitrate. Nitrite is formed in the presence of Nitrosomonas bacteria,, whereas nitrate is formed in the presence of Nitrobacter bacteria., The micro-organisms do not take place, Found in rainy season during lightning 2NO, The micro-organisms do not take place, Found in rainy season during lightning 2NO, lighthing, , 1. N2 O2 ( Nitric oxide) 2 NO2, 2. 2NO O2, , oxidation, , (Nitrogen per oxide), 3. 2NO2 H2O, HNO2 HNO3, , 4. 4NO2 2H 2O O2 4HNO3, (Nitric acid), 5. CaO 2HNO3 = Ca NO3 2 H2O, (Calcium nitrate), 6. HNO3 NH3 = NH4 NO3, (ammonium nitrate), , Class XI Biology, , www.vedantu.com, , 7
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7. HNO2 NH3 = NH 4 NO2, (Ammonium nitrite), Biological nitrogen fixation happens when nitrogen-fixing microorganisms like, Rhizobium are present. Diazotrophs are prokaryotes that fix nitrogen in a biological, way. Rhizobium is a symbiotic bacteria that dwells in the roots of leguminous plants., Nitrogenase is the enzyme responsible for biological nitrogen fixation. Both freeliving and symbiotic nitrogen-fixing bacteria exist. Azotobacter, Rhodospirillum,, Anabaena, and Nostoc are examples of free-living nitrogen-fixing aerobic bacteria., Leguminous plants, such as peas, beans, clover, alfalfa, and others, have a symbiotic, relationship with Rhizobium. Nitrogen-fixing is accompanied by the development, of distinctive nodules. The contact of Rhizobium with the roots of the plants is the, first step in the development of nodules. Certain compounds are released by these, plants, which attract bacteria to the plant's roots. Rhizobium produces a root hair, curling component that aids the bacteria's invasion of the roots. The nitrogenase, enzyme, which catalyses nitrogen fixation, is oxygen sensitive. During nitrogen, fixation, the enzyme leghemoglobin (a member of the hemoglobin family), scavenges oxygen., , nodule formation steps - Bing images, Steps of nodule formation during biological nitrogen fixation, The reaction catalyzed by the nitrogenase is as followsClass XI Biology, , www.vedantu.com, , 8
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nitrogenase, , N 2 12ATP ATP 2NH3 12ADP 12Pi, , nitrogen ammonia phosphate (atmospheric) (inorganic), It requires 12 ATPs to breakdown the strong triple bond that exist between the two, nitrogen atoms of N 2 gas: N N, The process of nitrogen fixation requires a lot of energy. To transform one molecule, of nitrogen into two molecules of ammonia, 16 ATP molecules are required., Plants are poisoned by the ammonia produced during nitrogen fixation. As a result,, this ammonia undergoes further reactions. Reductive amination is the reaction of ammonia with alpha-ketoglutaric acid to, produce glutamic acid or glutamate, as indicated in the diagram below:-, , Reductive amination and Transamination, Transamination: When an amino group from one amino acid is transferred to a, keto acid. Transaminases are enzymes that catalyse this process. Asparagine amino, acids are formed as a result of this process. As a result, poisonous ammonia is, transformed into necessary amino acids for plant growth and development., , Class XI Biology, , www.vedantu.com, , 9
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