Question

Structural organisation in animals attains different levels as cell - organ - organ system. What is missing in this chain? Mention the significance of such an organisation.

Answer 1

Tissue is missing in this chain. In multicellular animals, a group of similar cells along with intercellular substances perform a specific function. Such an organisation is called tissue. Tissues are organised in specific proportions and patterns to form an organ like stomach, lung, heart and kidney. When two or more organs perform a common function by their physical and/or chemical interaction, they together form organ systems, e.g., digestive system, respiratory system, etc. Cells, tissues, organs and organ systems split up the work in a way that exhibits division of labour and contributes to the survival of the body as a whole.