Describe the link between multicellular organisms and the concept of specialized cells.

Having levels of organization is a characteristic of life. Multicellular organisms are made of more than one cell ("multi" = many). The levels of organization within a multicellular organism are cells, cells make tissues, tissues make organs, organs make organ systems, and organ systems work together to make the overall organism. Therefore, multicellular organisms are like machines that are made of different parts. Each part is specialized to perform a certain task. All the machines...

Having levels of organization is a characteristic of life. Multicellular organisms are made of more than one cell ("multi" = many). The levels of organization within a multicellular organism are cells, cells make tissues, tissues make organs, organs make organ systems, and organ systems work together to make the overall organism. Therefore, multicellular organisms are like machines that are made of different parts. Each part is specialized to perform a certain task. All the machines work together in order complete the purpose task of the machine. If one part misfunctions, the overall performance of the machine is compromised or inhibited. 

Just like the parts of a machine, multicellular organisms contain specialized cells. The shape of the cells relate to their function (jobs or purposes within the multicellular organism). For example, nerve cells contain long axons because they need to carry messages from the brain or spinal cord to the organism's extremities. Likewise, red lack nuclei. This results in a disc-like shape. This allows the red blood cells to carry more hemoglobin, which carries oxygen to the body.