STRUCTURE AND FUNCTION OF CELL
You have learned that each living organism has many organs. You have studied in Class VII about the digestive organs which together constitute the digestive system. Each organ in the system performs different functions such as digestion, assimilation and absorption. Similarly, different organs of a plant perform specific/specialized functions. For example, roots help in the absorption of water and minerals. Leaves, as you have learned in Class VII, are responsible for the synthesis of food.
Each organ is further made up of smaller parts called tissues. A tissue is a group of similar cells performing a specific function.
Paheli realized that an organ is made up of tissues which in turn, are made up of cells. The cell in a living organism is the basic structural unit
Source: This topic is taken from NCERT TEXTBOOK