What is the definition of tissue in biological terms?

In biological terms, tissue is defined as a group of similar cells that join together to perform a particular function. This definition emphasizes the organization and specialization of cells which allows them to work collectively towards specific tasks that are essential for the proper functioning of an organism. Tissues can be categorized into four main types: epithelial, connective, muscle, and nervous tissue, each serving distinct roles in the body.

The other choices do not accurately reflect the definition of tissue. A collection of organs working together characterizes an organ system, while a type of connective material that supports organs pertains to connective tissue specifically, which is just one kind of tissue, not the entire concept. Lastly, a single cell functioning independently describes an individual cellular organism, rather than the collective nature of tissues.