Mention various forms and functions of essential mineral nutrients.

(N/A) $\Rightarrow$ Nitrogen: Absorbed as $NO_{3}^{-}, NO_{2}^{-}, NH_{4}^{+}$. Required in meristematic tissues and metabolically active cells. Major constituent of proteins,nucleic acids,vitamins,and hormones.
$\Rightarrow$ Phosphorus: Absorbed as $H_{2}PO_{4}^{-}$ or $HPO_{4}^{2-}$. Constituent of cell membranes,nucleic acids,and nucleotides. Required for all phosphorylation reactions.
$\Rightarrow$ Potassium $(K^{+})$: Absorbed as $K^{+}$. Required in meristematic tissues,buds,leaves,and root tips. Maintains anion-cation balance,protein synthesis,stomatal opening/closing,and cell turgidity.
$\Rightarrow$ Calcium $(Ca^{2+})$: Absorbed as $Ca^{2+}$. Required by meristematic and differentiating tissues. Used in cell wall synthesis (calcium pectate in middle lamella) and mitotic spindle formation. Involved in membrane functioning and enzyme activation.
$\Rightarrow$ Magnesium $(Mg^{2+})$: Absorbed as $Mg^{2+}$. Activates enzymes of respiration and photosynthesis. Involved in $DNA$ and $RNA$ synthesis. Constituent of chlorophyll ring structure and maintains ribosome structure.
$\Rightarrow$ Sulphur: Absorbed as $SO_{4}^{2-}$. Present in amino acids (cysteine,methionine). Constituent of coenzymes,vitamins (thiamine,biotin,Coenzyme $A$),and ferredoxin.
$\Rightarrow$ Iron: Absorbed as $Fe^{3+}$. Constituent of proteins involved in electron transfer (ferredoxin,cytochromes). Reversibly oxidized between $Fe^{2+}$ and $Fe^{3+}$. Activates catalase and essential for chlorophyll formation.
$\Rightarrow$ Manganese: Absorbed as $Mn^{2+}$. Activates enzymes in photosynthesis,respiration,and nitrogen metabolism. Essential for water-splitting reaction to liberate oxygen.
$\Rightarrow$ Zinc: Absorbed as $Zn^{2+}$. Activates carboxylases and required for auxin synthesis.
$\Rightarrow$ Copper: Absorbed as $Cu^{2+}$. Essential for overall metabolism and redox reactions. Reversibly oxidized between $Cu^{+}$ and $Cu^{2+}$.
$\Rightarrow$ Boron: Absorbed as $BO_{3}^{3-}$ or $B_{4}O_{7}^{2-}$. Required for $Ca^{2+}$ uptake/utilization,membrane functioning,pollen germination,cell elongation,and carbohydrate translocation.
$\Rightarrow$ Molybdenum: Absorbed as $MoO_{2}^{2+}$. Component of nitrogenase and nitrate reductase,involved in nitrogen metabolism.
$\Rightarrow$ Chlorine: Absorbed as $Cl^{-}$. Along with $Na^{+}$ and $K^{+}$,helps determine solute concentration and anion-cation balance. Essential for water-splitting reaction in photosynthesis.