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Question : Mention various forms and functions of essential mineral nutrients.

Answer»

Solution : Nitrogen : It is absorbed from soil as `NO_3^(-),NO_2^(-),NH_4^(+)`.
It is required in all parts of a plant particularly the meristematic tissues and metabolically active cells. It is ONE of the major constituents of proteins, nucleic acids, vitamins and HORMONES
Phosphorus : It is absorbed as `H_2PO_4^(2-) or HPO_4` from the soil.
Phosphorus is a constituents of cell membranes, certain proteins, all nucleic acids and nucleotides.
It Is required for all phosphorylation reactions.
Potassium `(K^+)`: It is absorbed as potassium ion `(K^+)` from the soil
In plants, this is required in more abundant quantities in the meristematic tissues, buds, leaves and root tips.
Potassium helps to maintain an anion-cation balance in cells.
It is involved in protein synthesis, opening and closing of stomata
It helps in maintenance of the turgidity of cells,
Calcium : (`Ca^(+2)`) It is absorbed as `Ca^(+2)` ion from the soiL
In plants it is required by meristematic and differentiating tissues
During cell division it is used in the synthesis of cell wall.
It is required particularly as calcium pectate in the middle lamella, also needed during the formation of mitotic spindle.
It accumulates in older leaves.
It is involved in the normal functioning of the cell membranes
It activates certain enzymes.
It plays an important role in regulating metabolic activities.
Magnesium : It is absorbed as ion of (`Mg^(+2)`).
It activates the enzymes of respiration, photosynthesis.
It is involved in the synthesis of DNA and RNA.
Magnesium is a constituent of the ring structure of chlorophyll.
It helps to maintain the ribosome structure.
Sulphur : It is obtained in the form of (`SO_4^(-2)`).
It is present in amino acids named as cysteine and methionine.
It is the main constituent of several coenzymes, vitamins (thiamine, biotin. Coenzyme A) and ferredoxin.
Iron : Plants obtain Iron in the form of ferric IONS (`Fe^(+3)`).
It is required in larger amounts in comparison to other micronutrients.
It is an important constituent of proteins involved in the transfer of electrons like ferredoxin and cytochromes.
It is reversibly oxidised form `Fe^(+2)` to `Fe^(+3)`during electron transfer.
It activates catalase enzyme.
It is essential for the formation of chlorophyll.
Manganese : It is absorbed in the form of manganous lons(`MN^(2+)`).
It activates many enzymes involved in photosynthesis, respiration and nitrogen metabolism.
The best DEFINED function of manganese is In the splitting of water to liberate oxygen during photosynthesis. It activates various enzymes especially carboxylases.
It is also needed in the synthesis of auxin.
Copper : It is absorbed as (`Cu^(+2)`) cupric ion.
It is essential for the overall metabolism processes In plants.
Like iron it is associated with certain enzymes involved in redox reactions
It is reversibly oxidised from `Cu^(+)` to `Cu^(+2)`.
Boron : absorbs in the form of `BO_3^(-3) or B_4O_7^(-2)`
For uptake and utilization of Cita, membrane functioning, pollen germination, cell elongation, cell differentiation and carbohydrate translocation.
Molybdenum : Obtained In the form of molybdate ions (`MoO_2^+`).
It k a component of several enzymes, including nitrogenase and nitrate reductase both of which participate in nitrogen metabolism.
Chlorine : It is absorbed in the form of chloride ion (`Cl^-`).
Along with `Na^+,K^+`It helps in detennining the solute concentration and the anion-cation balance In the cells.
It is essential for the water-splitting reaction in photosynthesis, a reaction that leads to oxygen evolution.


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