What definition best describes tissue?

The definition of tissue as a collection of similar cells that perform a specific function is accurate because tissues are indeed composed of cells that share common characteristics and work together to carry out a particular task. For example, muscle tissue consists of muscle cells working in unison to enable movement, while epithelial tissue functions as a protective covering or as a barrier for absorption and secretion.

Understanding this concept is fundamental in biology, as it lays the groundwork for comprehending how different types of tissues contribute to the overall function of organs and systems in an organism. Each tissue type—such as connective, muscle, nervous, and epithelial—has a unique role, whether it's providing support, enabling movement, transmitting signals, or covering surfaces. This specialization and organization into tissues are key to the complexity and functionality of multicellular organisms.