CBSE Class 10 Answered

The outside sources of energy is usually quite varied, since the environment is not under the control of the individual organism. Hence these energy sources need to be broken down or built up in the body, and finally converted to a uniform source of energy. Only then they can be used for the various molecular movements needed for maintaining living structures, as well as to the kind of molecules the body needs to grow.

This is accomplished through a series of ?chemical reactions in the?? ?body?.? ????????????????Oxidising-reducing reactions are some of the most ???common chemical means to break-down molecules, for which respiration is carried out by the organism. Many organisms use oxygen sourced from outside the body to break-down food sources for cellular needs.