All living creatures need food. The food is consumed so that energy is obtained. The energy is utilised by the body for various purposes like locomotion, conduction of impulses, repair of damaged tissues, building of cell materials, etc.
Glucose is a carbohydrate - a compound of carbon and hydrogen. The bonds between the carbon and the hydrogen atoms are very strong.
Respiration is an important process in nature. It is a process by which the solar energy trapped by the plants in the food can be utilised. The organic compounds are broken down to release energy.
Breathing provides the mechanism necessary to take in oxygen and give out carbon dioxide that is a waste gas. It is a physical process and part of respiration. Respiration is a biochemical and physical process.