Living organisms requires 6 elements in relatively large amounts. Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorus and Sulphur. These elements contribute to the structural organization of living organisms. Phosphorus is important constituent of nucleic acids, sulphur and nitrogen constituent of amino acids. Carbon, hydrogen, oxygen are frame-work element. Nitrogen forms DNA base pairs.
Related Theory
Plants obtained their supplies of material from air, water, and soil. Animais oblained these by eating plants and drinking water. All are present in rocks and are released by erosion and weathering into soils, rivers. lakes and oceans. Some such as $\mathrm{N}, \mathrm{O}$, and $C$ are also present in the atmosphere. The movement of the nutrient element through the biosphere is called the biogeochemical cycle. e.g., Carbon, nitrogen, sulphur, phosphorus, oxygen and water cycles.