NCERT Class 7 Science Textbook for Blind Students made Screen readable by Professor T K Bansal.

Plants are the only organisms that can prepare their own food of themselves by using water, carbon dioxide, and minerals. The raw materials are present in their surroundings. The nutrients enable living organisms to build their bodies, to grow, to repair damaged parts of their bodies, and provide the energy to carry out life processes. Nutrition is the mode of taking food by an organism and its utilization by the body. The mode of nutrition in which organisms make food themselves from simple substances is called autotrophic (auto means self; trophos means nourishment) nutrition. Therefore, plants are called autotrophs. Animals and most other organisms take in food prepared by plants. They are called heterotrophs (hetero means other).

Paheli wants to know why our bodies cannot make food from carbon dioxide, water, and minerals like plants do.

Now, we may ask ourselves that where are the food factories of plants located? whether the food is made in every part of a plant or only in certain parts? How do plants obtain raw materials from their surroundings? How do they transport them to the food factories of plants?