With the help of examples describe the classification of essential elements based on the function they perform.

Explanation

Essential elements are involved in performing variety of functions in plants. Some of the major functions are enlisted below
(i) Frame work elements Essential elements as components of biomolecules and hence are structural elements of the cell. Carbon, hydrogen and oxygen are considered as framework elements because they constitute carbohydrates which form cell wall.
(ii) Protoplasmic elements N, P and S are considered as protoplasmic elements as they form protoplasm along with C, H and oxygen.
(iii) Catalytic enzyme Essential elements that activates or inhibit enzymes, i.e., `Mg^(2+)` acts as an activator for both ribulose biphosphate carboxylase oxygenase (Rubisco) and phosphoenol pyruvate carboxylase (PEP carboxylase).
(iv) Balancing elements Elements counteract the toxic effect of other minerals by causing ionic balance (e.g., calcium, magnesium and potassium).
(v) Influencing of the osmotic pressure of the cell Some essential elements alters the osmotic potential of the cell. Plant cells contain dissolved mineral elements in the cell sap influencing osmotic pressure of the cell, e.g., K is involved in opening and closing of stomata.