What is nucleoid? How is it different from the nucleus of eukaryotic cell?

This division of labour operates at multiple organizational levels—specialized cells group together to form tissues (like cardiac muscle tissue), different tissues combine to create organs (like the heart), and organs work together in systems (like the circulatory system). This hierarchical organization allows for remarkable efficiency and complexity. Consider digestion: salivary gland cells produce enzymes, stomach lining cells secrete acid, intestinal cells absorb nutrients, and pancreatic cells produce hormones to regulate blood sugar—each contributing its specialized function to the overall process. This cooperative specialization enables multicellular organisms to grow larger, adapt to diverse environments, and perform complex functions that would be impossible for a single cell or group of identical cells. The downside is that specialized cells become interdependent, losing the ability to survive independently, unlike unicellular organisms where each cell is self-sufficient.