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Role of Macronutrients

Introduction:

  • The macronutrients are a part of essential elements and hence perform various important functions.
  • These macronutrients are involved in many metabolic processes in plant cells.
  • Maintenance of osmotic concentration of cell sap, electron-transport systems, buffering action, enzymatic activity are all performed by the essential elements and they also act as major constituents of macromolecules.

Detailed explanation:
 

i) Nitrogen :

  • It is required by the plants in maximum amount. It is absorbed mainly as NO3-; and at times as NO2- or NH4+.
  • Nitrogen is essential for all parts of the plant, especially meristematic tissues and metabolically active cells.
  • Nitrogen is an essential component of proteins, nucleic acids, vitamins and hormones.
  • Being a component of such a large number of biomolecules, it is essential for all type of metabolic activities such as photosynthesis, respiration, cell growth, cell division and reproductive growth.

ii) Phosphorus:

  • Phosphorus is taken up by the plants from the soil in the form of phosphate ions as H2PO4- or HPO42-.
  • In the plant, phosphorus is stored in developing fruits, seeds, storage organs and young meristematic tissues.
  • Phosphorus is an important component of cell membranes, certain proteins, all nucleic acids and nucleotides.
  • It is required for all phosphorylation reactions.
  • It is a component of an energy-related chemical compounds like ATP.

iii) Potassium:

  • It is taken up as the potassium ion (K+).
  • Most abundant intracellular ion.
  • The meristematic tissues, buds, leaves and root tips require K+ in much more quantities.
  • K+ is responsible for maintaining the anion-cation balance in cells.
  • It is also involved in protein synthesis.
  • It helps in opening and closing of stomata
  • It is responsible for activation of several enzymes.
  • It helps in maintaining the turgidity of cells.

iv) Calcium:

  • Plants take up calcium in the form of calcium ions (Ca2+) from the soil.
  • Calcium is needed by the meristematic tissues and the differentiating tissues.
  • While cell division it is required for the synthesis of the cell wall, particularly as calcium pectate that forms the middle lamella.
  • It is also needed during mitotic spindle formation and organisation of the chromosomes.
  • It gets accumulated in the older leaves.
  • Calcium plays a major role in the normal functioning of the cell membranes.
  • It can activate certain specific enzymes like ATPase, phospholipases, etc.
  • It plays an important role in regulating various metabolic activities.

v) Magnesium:

  • It is taken up in the form of divalent Mg2+ by the plants.
  • It is required in the growing areas of root and stem, seeds and leaves, etc.
  • Enzymes required in respiration, photosynthesis are activated by magnesium.
  • It is also involved in DNA and RNA synthesis.
  • The ring structure of chlorophyll has magnesium as its key component and ribosome structure is also maintained by it.

vi) Sulphur:

  • It is taken up by the plants in the form of SO42-.
  • We find sulphur in two very important amino acids, i.e. cysteine and methionine.
  • It is an important constituent of several coenzymes, vitamins (thiamine, biotin, Coenzyme A) and ferredoxin.
  • The deficiency of sulphur causes accumulation of anthocyanin.

Frequently Asked Questions: FAQs
 

Q1. State key roles played by macronutrients.
Ans:

  • The macronutrients are a part of essential elements and hence perform various important functions.
  • These macronutrients are involved in many metabolic processes in plant cells.
  • Maintenance of osmotic concentration of cell sap, electron-transport systems, buffering action, enzymatic activity are all performed by the essential elements and they also act as major constituents of macromolecules.

Q2. Which macronutrient is highly essential for phosphorylation reactions?
Ans:

  • Phosphorus is essential for all phosphorylation reactions.
  • It is taken up by the plants from the soil in the form of phosphate ions as H2PO4- or HPO42-.
  • In the plant, phosphorus is stored in developing fruits, seeds, storage organs and young meristematic tissues.

Q3. What is the key component of chlorophyll?
Answer:
The ring structure of chlorophyll has magnesium as its key component.

Q4. State the essential functions of nitrogen as a macronutrient.
Answer:

  • It is required by the plants in maximum amount. It is absorbed mainly as NO3-; and at times as NO2- or NH4+.
  • Nitrogen is essential for all parts of the plant, especially meristematic tissues and metabolically active cells.
  • Nitrogen is an essential component of proteins, nucleic acids, vitamins and hormones.
  • Being a component of such a large number of biomolecules, it is essential for all type of metabolic activities such as photosynthesis, respiration, cell growth, cell division and reproductive growth.

Q5. Which amino acids have sulphur as a key component?
Answer:
We find sulphur in two very important amino acids, i.e. cysteine and methionine.

Q6. State the role of magnesium in plant growth?
Answer:

  • It is taken up in the form of divalent Mg2+ by the plants.
  • It is required in the growing areas of root and stem, seeds and leaves, etc.
  • Enzymes required in respiration, photosynthesis are activated by magnesium.
  • It is also involved in DNA and RNA synthesis.
  • The ring structure of chlorophyll has magnesium as its key component and ribosome structure is also maintained by it.

Q7. Write the essential functions of calcium?
Answer:

  • Calcium is needed by the meristematic tissues and the differentiating tissues.
  • While cell division, it is required for the synthesis of the cell wall, particularly as calcium pectate forms the middle lamella.
  • It is also needed during mitotic spindle formation and the organisation of the chromosomes.
  • Calcium plays a major role in the normal functioning of the cell membranes.
  • t can activate certain specific enzymes like ATPase, phospholipases, etc.
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