What is a group of cells with similar function called?

A group of cells that perform a similar function is termed a tissue. Tissues are the organizational level of biological structure that sits between cells and organs in the hierarchy of biological complexity. Each tissue consists of cells that are specialized to carry out a particular function and work together to perform that function more efficiently.

For instance, in the human body, muscle tissue is composed of muscle cells that contract to facilitate movement, while nervous tissue consists of neurons that transmit signals. Understanding this classification is key to studies in biology and medicine, as it provides insight into how organisms are built and how they function.

The other options do not correctly describe a group of cells with similar functions. An organ is a structure made up of different types of tissues working together to perform specific tasks, a system consists of multiple organs that work together, and an organism refers to an individual living entity made up of various systems.