BY1- Levels of Organisation

Differentiation and Specialisation

Single-celled organisms carry out all life functions within a single cell. Multicellular organisms need specialised cells, forming tissues and organs, to carry out particular functions. As they develop, each cell becomes specialised in structure to suit the role it will perform.

Some cells remain unspecialised or undifferentiated and function as 'packing' cells, for example parenchyma cells in plants. Other cell can differentiate in a number of ways involving one, two or all three of the following changes:

• The shape of the cell- nerve cells become long and thin to carry impulses
• The number of…