Final answer:
Multicellularity in organisms denotes specialization and organization of cell types into tissues and systems, making signaling within multicellular organisms more complex than in single-celled organisms. They require specialized receptors and other mechanisms to coordinate functions and development across various cell types.
Step-by-step explanation:
Multicellular organisms are not inherently more advanced than single-celled organisms; rather, they simply have different biological complexities. Multicellularity requires not just multiple cells but a specialization of cell types and an organization into tissues, organs, and organ systems. This complexity means that signaling within multicellular organisms is more complicated due to the need for intricate communication and coordination among various cell types over potentially long distances.
Signal transduction in multicellular systems involves numerous steps, including the use of receptors for signaling, and typically takes more time compared to single-celled organisms. Single-celled organisms may communicate directly through the fusion of plasma membranes or by communication with immediately adjacent cells. In contrast, multicellular organisms must coordinate between distantly located cells, a process that is inherently more complex due to compartmentalization and the need for an organized developmental process.