All organisms perform many activities such as growth, reproduction, movement, etc. to perform all these activities of the body we need energy and this energy comes from food we eat after digestion the food is brought to the cell where is broken into carbon dioxide and water to release energy and this process is called respiration all the organisms respire to get energy so respiration is a vital function of body. OR The food material taken in during nutrition is used in cells to provide energy for various life processes. This energy is released during the process of respiration. The oxygen taken in during respiration is transported to cells for carrying out oxidation of food. This energy is stored in the form of ATP, which is used for the entire working of the body. Also, the CO2 released during respiration has to be removed immediately out of the body. So without respiration, the body will not get any energy to function in any way. Hence it is a vital function or process of the body.