Question

Nitrogen, phosphorous, potassium are example of
A. Micro- nutrients
B. Macronutrients
C. Fertilizers
D. Both A and B

Answer 1

Hint: These are essential nutrients that are needed by the plants to carry out its various metabolic activities. Nitrogen and phosphorus are the major components of the genetic material. These nutrients are majorly required in large quantities.

Complete answer:
Essential nutrients are needed for performing several functions in the plants. These nutrients are needed for many metabolic activities of the plant cell such as permeability , maintenance of osmotic concentration, concentration of cell sap, electron - transport system, buffering action, enzymatic activity and acts as major constituents of macromolecules and the co- enzyme.

Lets us know various function of the above nutrients:
1. Nitrogen- It is one of the essential nutrient element required by plants in the greatest amount. It is absorbed mainly as $NO_3$ though some are also taken up as $NO_2^{-} or $NH_4^{+}$.Nitrogen is required by all parts of plants ,particularly the meristematic tissues and the metabolically active cells.

2. Phosphorus -phosphorus is absorbed by the plants from soil in the form of phosphate ions Phosphorus is a constituent of cell membrane , certain proteins ,all nucleic acids and nucleotides,and is required for all phosphorylation reactions.

3. Potassium-It is absorbed as potassium ion. 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 and involved in protein synthesis, opening and closing of stomata,activation of enzymes and in the maintenance of the turgidity of cells.

All these nutrients come under the category of macronutrients. Macronutrients are generally those nutrients that are present in plant tissues in large amounts i.e, in excess 10mmole kg of dry waste.

Micronutrients- These are the nutrients that are required in very small quantities but their deficiency can cause major health problems. Example- Zinc, magnesium.

Fertilisers- Fertilisers are the artificial nutrients added to soil to improve its fertility. They are the compounds of nitrogen, phosphorus, potassium.

Therefore the correct answer is option ‘B’.

Note: Essential elements are most important in the aspect of plant growth and development. Essential elements are components of biomolecules and hence structural elements of cells .They are compounds of energy related chemical compounds in plants. Some essential elements ,potassium can alter the osmotic elements of the cell.