CBSE Class 9 Answered

(a) Biosphere consists of both biotic and abiotic components. The constant interactions between the biotic and abiotic components results in continuous transfer of food and energy. This interaction makes the system dynamic. Different elemental cycles such as water cycle, nitrogen cycle, carbon cycle etc. provide stability to the biosphere.

(b) When the biotic components such as plants and animals interact with the abiotic components such as soil and water of the biosphere, constant transfer of food and energy takes place. The flow of energy is unidrectional but the flow of nutrients is cyclic.

(c) When molecules such as glucose breakdown in the presence of oxygen, oxidation occurs and carbon dioxide gas (CO₂) is released along with the evolution of water (H₂O).