What defines a tissue in biological terms?

In biological terms, a tissue is defined as a group of cells that work together to perform a specific function or in a similar structure. Tissues are a fundamental organizational level of biological structures, lying between cells and organs in the hierarchy of biological organization. The cells within a tissue share a common origin and usually carry out related functions, such as providing support, protection, or movement.

The correct definition emphasizes the collaborative nature of the cells within a tissue, which may exhibit similar morphological characteristics and perform specific tasks. For instance, muscle tissue is made up of muscle cells that contract to enable movement, while epithelial tissue consists of cells that form protective barriers.

Other options do not fit the definition of a tissue. A mass of organs refers to multiple organs working together, which would more accurately describe an organ system. A cellular structure is too vague and could refer to individual cells or components within them rather than a collective group. Lastly, a type of organ system encompasses a broader integration of different tissues and organs functioning together, further distancing it from the specific definition of tissue.