Give the necessity of respiration in living organisms.

Explanation

All living organisms need energy for carrying our biological activities . This energy is obtained after the process of breathing . All living organisms need energy for carrying out daily life processes like absorption, transport, movement, reproduction. This energy we get from the food we have taken.
But in reality the process of breathing is very much connected to the process of release of energy from food.
Food : All the energy required for life processes is obtained by oxidation of some macronutrients that we call food.
Autotrophs : Only green plants and cyanobacteria can prepare their own food by the process of photosynthesis they trap light energy and convert into chemical energy that is stored in the bonds of carbohydrates like glucose, sucrose and starch.
In green plants too, not all cells, tissues and organs photosynthesise.
Only cells containing chloroplasts that are most often located in the superficial layers, carry out photosynthesis.
Heterotrophs : Animals are heterotrophs. They obtain food from plants directly or indirectly.
Saprophytes : Saprophytes like fungi are dependent on dead and decaying matter. All necessary food for life is obtained through photosynthesis