Question

Why do complex organisms need specialized cells

Answer 1

Multicellular organisms need organ systems so that different functions may take place. For example, our bodies are divided into numerous important systems that we depend on to live. Our respiratory system to breathe, which is where our lungs are, our digestive system to supply our cells with nutrients in order to function which is why we need sustenance. 

Answer 2

Complex organisms need cells that can perform many different functions. they need to be supported on a cellular level. Without specialized cells you they won't be able to perform different functions.