CBSE Class 11 Biology Mineral Nutrition Notes

Download CBSE Class 11 Biology Mineral Nutrition Notes in PDF format. All Revision notes for Class 11 Biology have been designed as per the latest syllabus and updated chapters given in your textbook for Biology in Standard 11. Our teachers have designed these concept notes for the benefit of Grade 11 students. You should use these chapter wise notes for revision on daily basis. These study notes can also be used for learning each chapter and its important and difficult topics or revision just before your exams to help you get better scores in upcoming examinations, You can also use Printable notes for Class 11 Biology for faster revision of difficult topics and get higher rank. After reading these notes also refer to MCQ questions for Class 11 Biology given our website

Mineral Nutrition Class 11 Biology Revision Notes

Class 11 Biology students should refer to the following concepts and notes for Mineral Nutrition in standard 11. These exam notes for Grade 11 Biology will be very useful for upcoming class tests and examinations and help you to score good marks

Mineral Nutrition Notes Class 11 Biology

12.Mineral Nutrition

POINTS TO REMEMBER :

Autotrophs : An organism that synthesize its required nutrients from simple and inorganic substances.

Heterotrophs : An organism that cannot synthesize its own nutrients and depend on others.

Essential Mineral elements :

• More than sixty elements found in different plants.

• Some plant accumulates selenium, some other gold.

Criteria for Essentiality :

• Element absolutely necessary for normal growth and reproduction.

• In the absence of the element the plant can not complete their life cycle.

• Role of the element can not be replaced by any other elements.

• The element must be directly involved in the metabolism of plant.

Macronutrients : are generally present in the plants tissues in large amount (in excess of 10 mmole Kg-1 of dry matter).

Micronutrients : or trace elements are needed in very small amounts (less than 10 mmole Kg-1 of dry matter)

Four group of essential elements :

• As components of biomolecules and forms structural elements of cells (e.g. carbon, hydrogen, oxygen and nitrogen)

• As components of energy-related chemical compounds in plants. (magnesium in chlorophyll and phosphorous in ATP)

• Element that activate or inhibit enzymes (Mg2+, Zn2+)

• Alter the osmotic potential of a cell. (K+)

Role of macro and micro-nutrients :

Nitrogen :

• Absorbed in the form of NO2- or NH4+

• Required by meristematic tissue and metabolically active tissue.

• Constituent of proteins, nucleic acids, vitamins and hormones.

Phosphorus :

• Absorbed in the form of H2PO4- or HPO42-.

• Constituents of cell membrane certain proteins, all nucleic acids and required in phosphorylation reaction.

Potassium :

• Absorbed as potassium ion (K+)

• Required in meristematic tissues.

• Maintain cation and anion balance in cell.

• Opening and closing of stomata.

• Activation of enzyme.

• Maintenance of turgidity of cells.

Calcium :

• Absorbed in the form of calcium ions (Ca2+).

• Required by meristematic and differentiating tissues.

• Used in synthesis of cell wall particularly as calcium pectate in middle lamella.

• Required during formation of mitotic spindle.

• Involved in normal functioning of cell membrane.

• Activate certain enzyme.

• Important role in regulating metabolic activity.

Magnesium :

• Absorbed in the form of Mg2+.

• Activates enzymes of respiration, photosynthesis.

• Involved in the synthesis of DNA and RNA.

• Constituent of the ring structure of chlorophyll.

• Maintain ribosome structure.

Sulphur :

• Absorbed in the form of sulphate SO42-.

• Present in two amino acids cystine and methionine

• Main constituent of several coenzyme, vitamins and ferredoxin.

Iron :

• Obtained in the form of ferric ions (Fe3+).

• Required in larger amount in comparison to other elements.

• Constituent of proteins involved in the transfer of electron like ferredoxin and cytochromes.

• Activates catalase enzyme.

• Essential for formation of chlorophyll.

Manganese :

• Absorbed in the form of manganous ions (Mn2+).

• Activates many enzymes of photosynthesis, respiration and nitrogen metabolism.

• Photolysis of water and evolution of oxygen during light reaction.

Zinc :

• Obtained in the form of Zn2+.

• Activates enzymes like carboxylase.

• Required in synthesis of auxin.

Cupper :

• Absorbed in the form of cupric ions (Cu2+).

• Essential for overall metabolism.

• Associated with enzyme involved in redox reactions. 

• Associated with enzyme involved in redox reactions.

Boron :

• Absorbed in the form of BO33- or B4O72-.

• Required in uptake and utilization of Ca2+.

• Pollen germination.

• Cell elongation.

• Cell differentiation.

• Carbohydrate translocation.

Molybdenum :

• Obtained in the form of molybdate ions (MoO22-).

• Component of enzyme like nitrogenase and nitrate reductase.

• Required in nitrogen metabolism.

Chlorine :

• Absorbed in the form of chloride anion (Cl-).

• Along with Na+ and K+ it determines the solute concentration.

• Maintain anion cation balance of the cell.

• Essential for photolysis of water during light reaction of photosynthesis.

Deficiency symptoms of essential elements :

• Critical concentration: the concentration of the essential element below which plant growth is retarded.

• The element is said to be deficient when present below the critical concentration.

• For the elements that are actively mobilized within the plant that show the deficiency symptoms in the older tissues. (nitrogen, potassium and magnesium)

• The deficiency symptoms tend to appear first in the young tissues whenever the elements are relatively immobile and are not transported out of the mature organs.(sulphur and calcium)

• Deficiency symptom includes chlorosis, necrosis, and stunted growth, premature fall of leaves and buds, and inhibition of cell division.

• Chlorosis: is the loss of chlorophyll.

• Necrosis: death of cells and tissues.

Toxicity of Micronutrients :

• Micronutrient required in low amount.

• Moderate decrease causes the deficiency symptoms.

• Moderate increase causes toxicity.

• Any mineral ion concentration in tissues that reduces the dry weight of the tissues by 10 percent is considered toxic.

Nitrogen cycle :

• Nitrogen fixation: conversion of molecular nitrogen into ammonia.

• Biological nitrogen fixation: Conversion of atmospheric into organic compounds by living organisms.

• Ammonification: decomposition of organic nitrogen of dead plants and animals into ammonia is called Ammonification. (Nitromonasbacteria)

• Nitrification. Ammonia oxidized into nitrite by NitrosomonasandNitrococcus bacteria. The nitrite further oxidized to nitrate with the help of Nitrobacter. These steps are called nitrification.

• Assimilation:

o Nitrates absorbed by plant from soil and transported to the leaves.

o In the leaves nitrates reduced to form ammonia that finally forms the amine group of amino acids.

• Denitrification: Nitrate in the soil is also reduced to molecular nitrogen. This process is carried by bacteria likePseudomonas and Thiobacillus.

Biological nitrogen fixation :

• Reduction of nitrogen to ammonia by living organisms is called biological nitrogen fixation.

• The enzyme nitrogenase which catalyses the process are present in prokaryotes, called nitrogen fixer.

• Nitrogen fixing microbes could be free-living or symbiotic.

• Free-living nitrogen fixing aerobic microbes are Azotobacter and Beijernickia.

• Free-living nitrogen fixing anaerobic microbes are Rhodospirilium.

• A number of cyanobacteria like Anabaena and Nostoc are free-living nitrogen fixer.

Symbiotic nitrogen fixation :

• Best example of symbiotic nitrogen fixation is observed in legume-Rhizobium bacteria.

• Rhizobium form root nodules in leguminous plants.

• Frankia also produces nitrogen-fixing nodules on the roots of non-leguminous plants (e.g. Alnus).

• Both Rhizobium and Frankia are free living in soil, but as symbiont, can fix atmospheric nitrogen.

• The root nodules contain pink coloured pigment contains a protein called leg-haemoglobin.

Nodule formation :

• Nodule formation involves a sequence of multiple interactions between Rhizobium and roots of the host plant.

• Rhizobia multiply and colonize the surroundings of roots and get attached to the epidermal and root hair cells.

• An infection thread is produced carrying the bacteria into the cortex of root.

• Bacteria released from the thread into the cells which differentiated into special nitrogen fixing cells.

• Nodule develops vascular connection for exchange of nutrients.

• The nodule contains an enzyme called nitrogenase.

• Nitrogenase is a Mo-Fe protein and catalyses the conversion of atmospheric nitrogen to ammonia.

• Nitrogenase is highly sensitive to molecular oxygen; it requires anaerobic condition.

• Nodule contains a special protein called leg-haemoglobin.

• Leg-haemoglobin acts as oxygen scavenger and provides anaerobic condition to the bacteria inside the nodules; protect the enzyme nitrogenase from oxidation.

• Ammonia synthesis by nitrogenase is energetically expensive process; 8 ATP required synthesizing each molecule of NH3.

Fate of ammonia :

• At physiological pH, the ammonia is protonated to form NH4+.

• Most of plant assimilated nitrate and ammonium ions.

• Reductive amination: the ammonia reacts with α-ketoglutaric acid and forms Glutamic acid.

• Transamination: it involves the transfer of amino group from one amino acid to the keto group of a keto acid.

• Glutamic acid is the main amino acid from which by the process of transamination other amino acids are synthesized.

• Two important amides – asparagines and glutamine found in the protein of plant.

• They are formed from two amino acids namely aspartic acid and Glutamic acid respectively.

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Chapter 14 Respiration in Plants
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Chapter 19 Excretory Products and their Elimination
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