(i) An autotrophic organism (like a green plant) uses outside raw materials such as carbod dioxide, water and minerals alongwith sunlight to make its own food by the process of photosynthesis.
(ii) A heterotrophic organism (like an animals) uses outside raw material such as readymade organic food to grow, develop, synthesise proteins and other substances needed in the body.
(iii) Most of the organisms use oxygen (of air) as outside material for breaking down food and releasing energy for themselves in a process called respiration.
