Discuss the advantages of cellular differentiation.
Multicellular organisms are large and their bodies are differentiated into different organs. This is a result of cell differentiation where certain cells become specialised to form particular tasks.
The features of different cells will vary according to their role in the body. Their shape may change – for example, epithelial cells in the ileum have projections called microvilli on their surface. Or their organelles proportions may be different – for example, muscle cells have more mitochondria than other cells, because they need the energy to power movement.
Multicellular organisms can be more efficient because of this cell specialisation.
3.5 Cell specialisation
Describe how cells are arranged into tissues.
Describe how tissues are arranged into organs and organ systems.
Very early in the embryo stage of development of an organism all cells are identical. But as the embryo continues to grow, the cells are differentiated according to which genes are switched on in different cells.
Tissues are groups of cells that perform the same function. They are grouped together for working efficiency.
An organ is a combination of different tissues that are grouped together to perform a variety of specific functions. For example, the lungs are a specialised gas exchange system with tissues that are exchange surfaces and other tissues that support airways.
Several organs may work together as an organ system to make the body more efficient. For example, the heart, arteries, and veins make up the circulatory system.
