One example of cell specialisation is the functioning of epithelial cells. These cells basically protect the epithelial tissue underneath them from damage or infection. Cell specialisation is a feature in multicellular organisms where there are separate roles for each type of cell.
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An example of cell specialization is the guard cell. The guard cell regulates the exchange of oxygen, water vapour and carbon dioxide in the plant cell. A cell is a basic structural and functional unit that is found in all organisms.