Level of Organisation

Level of Organisation

Levels of Organisation

Organism, Organ Systems, Organs, Tissues, Cells

  • The levels of organisation in biology can be thought of as a hierarchy, starting from the simplest structures and building up to the complexity of a whole organism.


  • All living things are made up of cells, which are the smallest unit of life.
  • In animals, these cells include red and white blood cells, nerve cells, and muscle cells.
  • In plants, cell types include root hair cells, xylem, and phloem cells.


  • A tissue is a group of similar cells that work together to carry out a particular function.
  • Examples of tissues include muscle tissue and nervous tissue in animals, and epidermis, mesophyll, and vascular tissue in plants.


  • An organ is a group of different types of tissues that work together to perform a specific function.
  • Examples of organs in the human body are the heart, lungs and liver. In plants, organs include leaves, stems and roots.

Organ Systems

  • An organ system is a group of organs that work together to perform a major function.
  • In the human body, examples of organ systems are the circulatory system, respiratory system, and digestive system. In plants, the root system and shoot system work together to support growth, reproduction, and survival.


  • Finally, all of these levels build up to form an organism, a complex individual living thing.
  • Each organism has many organ systems, which contain many organs, which contain many tissues, which are made up of cells.

An Overview of Biological Organisation

  • In summary, the different levels of organisation in biology in order of increasing complexity are: cells, tissues, organs, organ systems, and organisms.
  • Understanding these levels is crucial in the study of biology, as it helps us understand how the body works as a whole, and how different parts interact and depend on each other.